Asociación Geológica Argentina Serie D: Publicación Especial Nº 14 ISSN 0328-2767 PEG 2011 ARGENTINA CONTRIBUTIONS TO th THE 5 INTERNATIONAL SYMPOSIUM ON GRANITIC PEGMATITES 1945 A G A Mendoza, 2011 MENDOZA Front cover: Photographs of the San Luis I, an albite-spodumene type of granitic pegmatite. The dyke is folded and the core is intruded by a spodumene subtype pegmatite called San Luis II. Outcrops of peripheral pegmatitic lenses of the parental Paso del Rey leucogranite are shown at the upper right part of the landscape. Back cover: Photograph of the texturally heterogeneous Cerro La Torre pegmatitic leucogranite intruding micaschists of the Pringles Metamorphic Complex (SW to NE view). The horizon line is broken by the Los Cerros Largos Tertiary volcanic dome. th The Organizing Committee of the 5 International Symposium on Granitic Pegmatites disclaims all responsibility for accuracy of the contents of the contributions published in this volume. Diseño editorial: Susana Graciela Farías Diagramación: Remedios Marín y Silvina Pereyra Corrección: Silvina Pereyra Servicio de Diseño Gráfico. CCT CONICET Mendoza Mendoza 2010 CONTRIBUTIONS TO THE 5TH INTERNATIONAL SYMPOSIUM ON GRANITIC PEGMATITES Mendoza, Argentina, February 20-27th 2011 EDITORS Miguel Ángel Galliski IANIGLA, CONICET, Argentina Encarnación Roda Robles, Universidad del País Vasco, Bilbao, Spain Frédéric Hatert, Université de Liège, Belgium María Florencia Márquez-Zavalía IANIGLA, CONICET, Argentina GUEST EDITORIAL BOARD Hartmut Beurlen Universidad Federal de Pernambuco, Brazil Alexander Lima Universidade do Porto, Portugal Raúl Lira Universidad Nacional de Córdoba, Argentina David London University of Oklahoma, USA Robert Martin McGill University, Canada Joan Carles Melgarejo Universidad de Barcelona, Spain Milan Novák Masaryk University, Czech Republic Wm. B. Simmons University of New Orleans, USA iiiASOCIACIÓN GEOLÓGICA ARGENTINA, SERIE D, PUBLICACIÓN ESPECIAL Nº 14 (2011) PREFACE Petr Černý with a giant crystal of beryl in the La Rosanna pegmatite, San Luis (April 2001). The 5th biennial edition of the “International Symposium on Granitic Pegmatites” designated “PEG2011 ARGENTINA”, will be held in the city of Mendoza, Argentina from 20 to 27 of February, 2011. This conference follows in the sequence of former meetings held in Brno (2003), Elba (2005), Porto (2007) and Recife (2009). This meeting has attracted the participation of 125 resear- chers, from 18 different countries on 5 continents, and will be highlighted by 4 invited lecturers and 55 extended abstracts about mineralogy (28), geochemistry (10), petrology and pe- trogenesis (21). The three-day conference (February 21-23) will hold the oral and poster presentations. The post-symposium Field Trip (February 24-27) will visit the San Luis ranges, and will permit the observation, discussion and sampling of diffe- rent kinds of granitic pegmatites outcropping in the southern districts of the Pampean pegmatite province. The occasion was also considered appropriate to celebrate and honor the life-long academic path of Dr. Petr Černý, for his outstanding dedication to the investigation of the mineralogy, geochemistry and petrogenesis of granitic pegmatites. Dr.Černý has been a Corresponding Member of the Asociación Geológica Argentina since 2001, and has particularly contributed to the knowledge base of Argentinean pegmatites, participating in the description of two new minerals and in studies about the mineralogy of pegmatitic assemblages of oxides, phosphates and silicates. vASOCIACIÓN GEOLÓGICA ARGENTINA, SERIE D, PUBLICACIÓN ESPECIAL Nº 14 (2011) INVITED LECTURES CONSTITUTIONAL ZONE REFINING AND THE INTERNAL EVOLUTION OF GRANITIC PEGMATITES David London ..........................................................................................................................................................................................1 PEARLS OF WISDOM GLEANED FROM MY MENTORS: WAYNE BURNHAM, FRANK TUTLE AND DICK JAHNS Robert F. Martin ......................................................................................................................................................................................5 TOURMALINE IN GRANITIC PEGMATITES Milan Novák ............................................................................................................................................................................................9 GEOCHEMISTRY OF REE–RICH PEGMATITES FROM DIFFERENT TECTONO-MAGMATIC PROVINCES IN SOUTH PLATTE, CO, TROUT CREEK PASS, CO, KINGMAN AND AQUARIUS RANGE, AZ, NORTH AMERICA William Simmons, Karen Webber, Alexander U. Falster, Sarah Hanson & TJ Brown ...............................................................13 CONTRIBUTIONS THE DISTRICTS OF THE EASTERN PEGMATITE PROVINCE OF BRAZIL Nelson Angeli ........................................................................................................................................................................................17 THE MICROLITE-GROUP MINERALS: NOMENCLATURE Daniel Atencio & Marcelo B. Andrade ..............................................................................................................................................21 GEOCHEMICAL EVOLUTION OF PHOSPHATES AND SILICATES IN THE SAPUCAIA PEGMATITE, MINAS GERAIS, BRAZIL: IMPLICATIONS FOR THE GENESIS OF THE PEGMATITE Maxime Baijot, Frédéric Hatert, André-Mathieu Fransolet & Simon Philippo ...........................................................................25 MORPHOLOGY AND PYROELECTRICITY OF TOURMALINE FROM CENTRAL TRANSBAIKALIA, RUSSIA Vladimir Bermanec, Andrea Čobic, Vladimir Zebec, Snježana MikulČic Pavlakovic & Victor Zagorsky ...............................29 MINERALOGY OF THE BOA VISTA PEGMATITE, GALILÉIA, MINAS GERAIS, BRAZIL Vladimir Bermanec, Ricardo Scholz, Frane Markovic, Željka ŽigoveČki Gobac & Mario Luiz De Sá Carneiro Chaves.....................................................................................................................................................................................................33 BORON-ISOTOPE VARIATIONS IN TOURMALINE FROM GRANITIC PEGMATITES OF THE BORBOREMA PEGMATITE PROVINCE, NE-BRAZIL Hartmut Beurlen, Robert B. Trumbull, Michael Wiedenbeck & Dwight R. Soares ....................................................................37 CHEMICAL CHARACTERIZATION AND CHROMOPHORE ELEMENTS IN ELBAITES FROM BORBOREMA PROVINCE, BRAZIL Sandra De Brito Barreto, Andrea Čobic, Željka ŽigoveČki Gobac, Vladimir Bermanec & Goran Kniewald ..........................41 PRELIMINARY FLUID INCLUSION RESULTS FROM THE RUBICON PEGMATITE, KARIBIB, NAMIBIA Luisa Broccardo, Judith A. Kinnaird & Paul A.M. Nex ...................................................................................................................45 A METASTABLE DISEQUILIBRIUM ASSEMBLAGE OF HYDROUS HIGH-SANIDINE ADULARIA + LOW ALBITE FROM LA VIQUITA GRANITIC PEGMATITE, SAN LUIS PROVINCE, ARGENTINA Petr Černý, Miguel A. Galliski, David K. Teertstra, Viviana M. Martínez, Ron Chapman, Luisa Ottolini, Lyndsey MacBride & Karen Ferreira ..................................................................................................................................................................49 CRYSTAL CHEMISTRY OF BLUE GENTHELVITE FROM THE EL CRIOLLO PEGMATITE, CÓRDOBA (ARGENTINA) Fernando Colombo & José González Del Tánago ............................................................................................................................53 THE NYF-TYPE MIAROLITIC-RARE EARTH ELEMENTS PEGMATITES OF THE EL PORTEZUELO GRANITE, PAPACHACRA (CATAMARCA, NW ARGENTINA) Fernando Colombo, Raúl Lira, William Simmons & Alexander U. Falster .................................................................................57 OCCURRENCE AND CRYSTAL CHEMISTRY OF ZIRCON FROM THE NYF-TYPE MIAROLITIC PEGMATITES OF THE EL PORTEZUELO GRANITE, PAPACHACRA (CATAMARCA, NW ARGENTINA) Fernando Colombo, William Simmons, Alexander U. Falster & Raúl Lira .................................................................................61 vi OCCURRENCE, CRYSTAL CHEMISTRY AND ALTERATION OF THORITE FROM THE NYF-TYPE MIAROLITIC PEGMATITES OF THE EL PORTEZUELO GRANITE, PAPACHACRA (CATAMARCA, NW ARGENTINA) Fernando Colombo, William Simmons, Alexander U. Falster & Raúl Lira .................................................................................65 MINERALOGY OF A HIGHLY FRACTIONATED REPLACEMENT UNIT FROM “ÁNGEL” PEGMATITE, COMECHINGONES PEGMATITIC FIELD, CÓRDOBA, ARGENTINA Manuel Demartis, Joan C. Melgarejo Draper, Pura Alfonso, Jorge E. Coniglio, Lucio P. Pinotti & Fernando J. D’Eramo ..................................................................................................................................................................................................69 PEGMATITE EMPLACEMENT DURING COMPRESSIONAL DEFORMATION OF THE GUACHA CORRAL SHEAR ZONE, CÓRDOBA, ARGENTINA Manuel Demartis, Lucio P. Pinotti, Fernando J. D’Eramo, Jorge E. Coniglio & Hugo A. Petrelli ............................................71 THE ROLE OF PEGMATITES IN THE “CHESSBOARD CLASSIFICATION SCHEME” (CCS) OF MINERAL DEPOSITS Harald Dill .............................................................................................................................................................................................75 PRELIMINARY RESULTS OF A NEWLY-DISCOVERED LAZULITE-SCORZALITE PEGMATITE-APLITE IN THE HAGENDORF- PLEYSTEIN PEGMATITE PROVINCE, SE GERMANY Harald G. Dill, Radek Škoda & Berthold Weber ..............................................................................................................................79 THE WAUSAU SYENITE COMPLEX, MARATHON COUNTY, WISCONSIN Alexander U. Falster, Thomas W. Buchholz & William B. Simmons ............................................................................................83 ZONED FOITITESCHORLDRAVITEMAGNESIOFOITITE CRYSTALS FROM POCKETS IN ANATECTIC PEGMATITES OF THE MOLDANUBIAN ZONE, CZECH REPUBLIC Petr Gadas, Milan Novák, Jan Filip & Josef Stan k ........................................................................................................................87 A MUSCOVITE PEGMATITE FIELD LOCATED IN A LOWER PALEOZOIC OROGENIC ARC: THE VALLE FÉRTIL DISTRICT, SAN JUAN, ARGENTINA Miguel A. Galliski, Brígida Castro de Machuca, Julio C. Oyarzábal, Estela Meissl, Alicia Conte Grand & María Belén Roquet .................................................................................................................................................................................................... 91 ASSOCIATION OF SECONDARY Al-Li-Be-Ca-Sr PHOSPHATES IN THE SAN ELÍAS PEGMATITE, SAN LUIS, AR- GENTINA Miguel A. Galliski, Petr Černý, María Florencia Márquez-Zavalía & Ron Chapman ................................................................95 THE DUMORTIERITE-BEARING ASSEMBLAGES OF VIRORCO, SAN LUIS, ARGENTINA: ARE THEY PEGMATITIC DYKES OR HYDROTHERMAL VEINS? Miguel A. Galliski, María Florencia Márquez-Zavalía & Raúl Lira ..............................................................................................99 THE CRYSTAL CHEMISTRY OF OLIVINE-TYPE PHOSPHATES Frédéric Hatert, Luisa Ottolini, François Fontan, Paul Keller, Encarnación Roda-Robles & André-Mathieu Fransolet .....103 MAGMATIC LAYERING (UNIDIRECTIONAL SOLIDIFICATION TEXTURES AND Y-ENRICHED GARNET TRAIN TEXTURES) IN APLITE – PEGMATITES OF THE CADOMIAN BRNO BATHOLITH, CZECH REPUBLIC Sven Hönig, Jaromír Leichmann & Milan Novák ..........................................................................................................................107 RECENT DEVELOPMENTS IN THE INVESTIGATION OF POLISH PEGMATITES Janusz Janeczek & Eligiusz Sze g ...................................................................................................................................................111 THE OCCURRENCE OF BETAFITE IN PEGMATITIC SHEETED URANIFEROUS GRANITES OF THE CENTRAL ZONE OF THE DAMARA OROGEN Judith Kinnaird, Paul Nex & Guy Freemantle ................................................................................................................................115 GEOCHEMICAL EVOLUTION AND PETROGENESIS OF RARE ELEMENT PEGMATITES IN THE SOLBELDER RIVER BASIN (SOUTH SIBERIA, RUSSIA) Liudmila Kuznetsova .........................................................................................................................................................................119 UNUSUAL TEXTURAL RELATIONSHIPS BETWEEN SPODUMENE AND PETALITE AT SPODUMENE BEARING APLITE- PEGMATITE OF BARROSO-ALVAO FIELD (NORTHERN PORTUGAL) Alexandre Lima & Tania Martins .....................................................................................................................................................123 TABLE OF CONTENTS viiASOCIACIÓN GEOLÓGICA ARGENTINA, SERIE D, PUBLICACIÓN ESPECIAL Nº 14 (2011) GRANITIC PEGMATITE CHRYSOBERYL IN A SHEAR ZONE OF THE ACHALA BATHOLITH, CÓRDOBA, ARGENTINA Raúl Lira & Jorge Sfragulla ................................................................................................................................................................127 COMPETING MODELS FOR THE INTERNAL EVOLUTION OF GRANITIC PEGMATITES David London ......................................................................................................................................................................................131 PETALITE RARE-METAL PEGMATITES OF THE EAST SAYAN BELT, EASTERN SIBERIA, RUSSIA: GEOLOGICAL SETTING, MINERALOGY, GEOCHEMISTRY AND GENESIS Vladimir Makagon ..............................................................................................................................................................................135 THE REGIONAL DISTRIBUTION OF TRACE ELEMENTS IN QUARTZ OF SOUTH NORWEGIAN PEGMATITES AND ITS TECTONOMAGMATIC IMPLICATIONS Axel Müller ..........................................................................................................................................................................................139 GEOCHEMISTRY OF GRANITIC APLITE-PEGMATITE VEINS AND SILLS AND THEIR MINERALS FROM CABEÇO DOS POUPOS, SABUGAL, CENTRAL PORTUGAL Ana M. R. Neiva, Paulo B. Silva & João M.F. Ramos .....................................................................................................................141 REGIONAL ZONATION OF PEGMATITES AND SYNCHRONOUS MINERALIZATION IN THE CENTRAL ZONE OF THE DAMARA OROGEN, NAMIBIA Paul Nex, Judith Kinnaird & Luisa Broccardo ................................................................................................................................145 COMPOSITIONAL VARIATIONS IN PRIMARY AND SECONDARY TOURMALINE FROM THE QUINTOS PEGMATITE, BORBO- REMA PEGMATITE PROVINCE, BRAZIL; REDISTRIBUTION OF Cu, Mn, Fe AND Zn IN SECONDARY TOURMALINE Milan Novák, Petr Gadas, Radek Škoda, Hartmut Beurlen & Odúlio J. M. de Moura ............................................................149 RHEOLOGY OF FLUID-SATURATED GRANITIC AND PEGMATITE-FORMING MELTS Igor S. Peretyazhko .............................................................................................................................................................................153 OCCURRENCE OF COMPLEX PEGMATITES IN THE SOUTH OF TOCANTINS STATE, BRAZIL Hudson Queiroz, Rúbia R. Viana, Gislaine A. Battilani, Luana Laiame de Oliveira, Gilliard Medeiros Borges & Denis L. Guerra ...................................................................................................................................................................................157 CATION PARTITIONING BETWEEN MINERALS OF THE TRIPHYLITE ± GRAFTONITE ± SARCOPSIDE ASSOCIATION IN GRANITIC PEGMATITES Encarnación Roda-Robles, Miguel A. Galliski, James Nizamoff, William Simmons, Paul Keller, Alexander Falster & Frédéric Hatert ................................................................................................................................................................................161 CHEMICAL VARIATION IN TOURMALINE FROM THE BERRY-HAVEY PEGMATITE (MAINE, USA), AND IMPLICATIONS FOR PEGMATITIC EVOLUTION Encarnación Roda-Robles, William Simmons, James Nizamoff, Alfonso Pesquera, Pedro P. Gil-Crespo & José Torres-Ruiz ...........................................................................................................................................................................................165 THE NYF PEGMATITES OF THE POTRERILLOS GRANITE, SIERRAS DE SAN LUIS, ARGENTINA María Belén Roquet, Federico Bernard, Raúl Lira & Miguel A. Galliski ...................................................................................169 TECHNOLOGICAL CHARACTERIZATION OF MUSCOVITE FROM THE PEGMATITES DISTRICTS OF CRISTAIS - RUSSAS (DPCR) AND SOLONÓPOLE - QUIXERAMOBIM (DPSQ) – CEARÁ, NORTHEAST BRAZIL Gabriela Meireles Rosa, Martha Noélia Lima, Débora Macedo do Nascimento, Tereza Falcão de Oliveira Neri, Francisco Diones Oliveira Silva, Andressa de Araujo Carneiro, José de Araújo Nogueira Neto & José Cleyton Vasconcelos ..........................................................................................................................................................................................173 K-FELDSPAR MINERALS DEFINED FROM THEIR TWIN-STRUCTURE: APPLICATION TO A PRELIMINARY CLASSIFICATION OF PEGMATITES Luis Sánchez-Muñoz, Javier García-Guinea, Victor Zagorsky, Odulio J. M. de Moura & Peter J. Modresky……………………175 TWIN-STRUCTURES IN K-FELDSPAR FROM OROGENIC AND ANOROGENIC PEGMATITES IN CENTRAL NORTH AMÉRICA Luis Sánchez-Muñoz, Peter J. Modreski & B. Ronald Frost ..........................................................................................................179 Rb-Sr GEOCHRONOLOGY FOR “LA AURORA” ANDALUSITE-BEARING PEGMATITE FROM MAZAN RANGE, NW viii ARGENTINA Fernando Sardi, F. & José Manuel Fuenlabrada Pérez ..................................................................................................................185 MAGMATIC DIFFERENTIATION IN THE HUACO GRANITE AND ITS ASSOCIATED Be-PEGMATITES FROM THE VELASCO DISTRICT, ARGENTINA Fernando Sardi, Mamoru Murata & Pablo Grosse ........................................................................................................................189 MINERALOGY OF THE LITHIUM BEARING PEGMATITES FROM THE CONSELHEIRO PENA PEGMATITE DISTRICT (MI- NAS GERAIS, BRAZIL) Ricardo Scholz, Mário Luiz de Sá Carneiro Chaves & Klaus Krambrock ..................................................................................193 CONCURRENT TREATMENT OF METAMICT AND CRYSTALLINE FERGUSONITE BY U, Th AND Pb-RICH FLUIDS: AN EMPA AND TEM STUDY Radek Škoda, Renata Čopjaková & Mariana Klementová ............................................................................................................197 TOWARDS EXPLORATION TOOLS FOR HIGH PURITY QUARTZ AND RARE METALS IN THE SOUTH NORWEGIAN BAMBLE-EVJE PEGMATITE BELT Benjamin R. Snook, Axel Müller, Ben J. Williamson & Frances Wall ..........................................................................................201 MINERAL CHEMISTRY OF ELBAITE FROM THE SERRA BRANCA PEGMATITE, NEAR PEDRA LAVRADA, STATE OF PARAÍBA, NE-BRAZIL Dwight R. Soares, Hartmut Beurlen, Ana Claudia M. Ferreira & Ranjana Yadav ....................................................................205 SECONDARY Ta-Nb OXIDE MINERALS OF THE ARCHAEAN WODGINA PEGMATITE DISTRICT, WESTERN AUSTRALIA, AND THEIR SIGNIFICANCE Marcus T. Sweetapple & Gregory R. Lumpkin ..............................................................................................................................209 MINERALS FROM THE CROSS LAKE PEGMATITE, MANITOBA, CANADA Kimberly T. Tait, Frank C. Hawthorne & Petr Černý ....................................................................................................................213 PARAGENETIC CONTROL AND COMPOSITIONAL EVOLUTION OF THE COLUMBITE-TANTALITE OXIDES FROM THE FREGENEDA- ALMENDRA LITHIUM-RICH PEGMATITES (PORTUGAL & SPAIN) Romeu Vieira, Encarnación Roda-Robles, Alexandre Lima, Alfonso Pesquera, Petr Gadas & Milan Novák ......................217 U-Pb LA-ICPMS COLUMBITE-TANTALITE AGES FROM THE PAMPEAN PEGMATITE PROVINCE: PRELIMINARY RESULTS Albrecht Von Quadt & Miguel A. Galliski ....................................................................................................................................221 MIAROLITIC PEGMATITES AND GRANITES FROM THE SEARCHLIGHT DISTRICT, COLORADO RIVER EXTENSIONAL CORRIDOR, NEVADA, USA Karen Webber, William Simmons & Alexander Falster ................................................................................................................225 THE ZAVITAYA LITHIUM-RICH GRANITE–PEGMATITE SYSTEM, CENTRAL TRANSBAIKALIA, RUSSIA: GEOLOGY, GEOCHEMISTRY, AND PETROGENETIC ASPECTS Victor Zagorsky ...................................................................................................................................................................................229 TABLE OF CONTENTS CONSTITUTIONAL ZONE REFINING AND THE INTERNAL EVOLUTION OF GRANITIC PEGMATITES David London ConocoPhillips School of Geology & Geophysics: dlondon@ou.edu. University of Oklahoma, 100 East Boyd Street, room 710 SEC, Norman, OK USA 73019 Key words: pegmatite, granite, granitic liquid, fluxing components, liquidus undercooling The most successful models for the origins and internal evolution of granitic pegmatites are those that have been the most holistic in their approach and with the strongest scientifi c basis. The longstanding success of the Jahns-Burnham model (1969) combines these attributes: the breadth of Jahns’ knowledge of pegmatites strengthened by Burnham’s innovative and exacting experimental programs. What made the Jahns-Burnham model so successful was its claim to a scientifi c proof through experimental petrology. Except for a few early abstracts, however, the details of that experimental evidence were not published by Jahns or Burnham. Some experimental programs completed by their students contradicted the underlying precepts of the Jahns-Burnham model (e.g., Kilinc 1969; Fenn 1986). A holistic model for the origin and internal evolution of granitic pegmatites must focus on those that are most abundant. These “common” pegmatites are represented, for example, by the tens of thousands of dikes exposed along the Appalachian Mountains, and typifi ed by occurrences in the Spruce Pine district, NC. They possess bulk compositions very close to those of the haplogranite (Ab-Or-Qtz) minimum; deviations from the metaluminous minimum occur toward peraluminous, not peralkaline compositions (this does not pertain to or include syenite-associated alkaline pegmatites). With only accessory levels of tourmaline, micas, apatite, or fluorite, they lack evidence for high concentrations of the fl uxing components of B, P, or F. Other than the subsolidus formation of microcline perthite, internal hydrothermal alteration is absent. Other than a rare and thin (1-2 mm) border reaction that produces tourmaline or metasomatic biotite, hydrothermal alteration of host rocks is nil. Miarolitic cavities are essentially nonexistent. Most common pegmatites lack foliation, and hence their emplacement postdates tectonism and its associated metamorphism. They possess sharp contacts with their host rocks. These and other pegmatites are completely devoid of entrained phenocrysts, and hence appear to be emplaced in the fully liquid state. Common granitic pegmatites are not hydrothermal in origin. This is because hydrothermal fluids of metamorphic rocks or of typical granitic plutons are Cl-dominant aqueous fl uids in which Al is notably insoluble (e.g., Anderson & Burnham 1983). Such fl uids can transport alkalis and silica, but not Al. Porphyry Cu deposits represent a case in point. Although they achieve saturation in a Cl-brine early in their magmatic history (Cline & Bodnar 1991), they are devoid of pegmatitic textures. Their hydrothermal systems transport and deposit massive quartz, but not feldspars and micas. Alkali-H exchange reactions occur in and around the porphyries, but all can be balanced with conservation of Al (i.e., Al is immobile). In contrast, porphyry-Mo deposits and so-called rare-element or “apo-” granites, which contain elevated concentrations of B, P, and/or F, always possess some domains of pegmatitic texture. It appears that H2O alone in granitic systems does not produce pegmatites, but H2O in combination with B, P, and/or F does promote the formation of pegmatitic textures in granites. The fl uxes of B, P, and F, together with H, have been implicated with pegmatite formation since the earliest proposed models (see London 2008), for the reason that these components reduce the liquidus and especially solidus temperatures (which extends the interval of magmatic crystallization), they lower the viscosity of melt (which facilitates the mass transfer needed to grow large crystals), and, they enhance the solubility and miscibility between otherwise less soluble or miscible components. The quantities of fl uxing components conserved within pegmatite minerals increases from nil in common pegmatites to locally abundant in the rare-element pegmatites. However, the Tanco pegmatite, Manitoba, which is arguably the most fractionated igneous body known, contains ~ 1 wt% total of B, P, and F components (Stilling et al. 2006). Morgan and London (1989) calculated the mass transfer associated with the loss of rare alkalis, B, and F from the pegmatite to the mafi c host rocks. When added back into the Tanco bulk composition, the fl uxes increase only to ~ 2 wt% of the ASOCIACIÓN GEOLÓGICA ARGENTINA, SERIE D, PUBLICACIÓN ESPECIAL Nº 14: 1-3 (2011) 2 CONSTITUTIONAL ZONE REFINING AND THE INTERNAL EVOLUTION OF GRANITIC PEGMATITES pegmatite total. Therefore, a model that addresses the origins of granitic pegmatites, which is as applicable to the common pegmatites as the rare-element- enriched bodies, must explain their origins in terms of the known rheological properties and crystallization behavior of hydrous haplogranitic granitic liquids, with non-negligible but small quantities of the fl uxing components of H (up to H2O-saturation at 6-7 wt% of melt), B, P, and F (from < 1 wt% total up to ~ 1-2 wt % each), and without the fl uxing effects of excess alkalis in their bulk compositions (i.e., the liquids are metaluminous to peraluminous). Granitic pegmatites of all types mostly occur near the margins and are concentrated in the cupolas of their source granites, from which they emanate hundreds of meters to several km from their source. By virtue of this occurrence, pegmatite-forming melts are juxtaposed against cooler host rocks. The relations of crystal nucleation to cooling (Fenn 1977; Swanson 1977; London 2008) indicate that pegmatite-forming melts are likely to be undercooled by 150-250°C below their liquidus temperatures, regardless of the rate of cooling, before appreciable crystal nucleation and growth commences. For H2O-saturated haplogranitic liquids at pressures > ~ 200 MPa and liquidus temperature (~ 700°C), the temperatures of crystallization, therefore, should be ~ 550 to 450°C. Numerical cooling models for proximal common pegmatites to distal rare-element bodies predict rapid cooling of melt at the dike margins to 500°-450°C (London 2008). Temperatures calculated from coexisting integrated perthite-plagioclase are 500°-450°C (London 2008), and where present, wallrock alteration assemblages are indicative of zeolite to lower greenschist facies conditions (~ 350°- 500°C: e.g., Morgan & London, 1987). Thus, there is good agreement among four distinctly different data sources: experiments on nucleation in the granite system, numerical modeling of heat fl ow, measured feldspar compositions within pegmatites, and wallrock alteration assemblages where present. This application exemplifi es the value of the holistic approach to understanding pegmatites. If the crystallization of pegmatite from margin to center keeps pace with cooling along the 450°- 500°C isotherm, as is suggested by two-feldspar thermometry, then the rates of crystal growth must be ~ 104 faster than those that are recorded from experiments (Swanson 1977; Fenn 1977). The published crystal growth rate experiments do not account for the nucleation delay or the cessation of crystal growth after nucleation; the actual rates of crystal growth in natural systems could be orders of magnitude faster than the experimentally-derived values. The effects of liquidus undercooling dominate the textures of the outer zones of pegmatites, which are fi ne-grained and strongly anisotropic. From a kinetic standpoint, even giant crystals of graphic granite are fi ne-grained in terms of the short diffusive distance of Al and of Si between nucleation centers for feldspar and for quartz, respectively. These are all attributable to rapid growth from a silicate liquid that is highly supersaturated with respect to feldspar- and quartz-forming components. The high degree of supersaturation results from of a long nucleation delay in the granite system. The delay in nucleation derives principally from the viscosity of the liquid, not the rate of cooling. At the magnitude of liquidus undercooling that is indicated for most granitic pegmatites (200°-250°C), the calculated viscosity of an H2O-saturated granitic liquid will be near 107-8 Pas, which is greater than the viscosity of asphaltic tar at 25°C. High viscosity of the undercooled granitic liquid is the primary cause for the graphic intergrowths (Fenn 1986) and other anisotropic fabrics of granitic pegmatites. The viscous granitic melt can deliver high fl uxes of the slow-diffusing components, Al and Si, but only over short distances at the rate of pegmatite cooling; hence, the fi ne-grained nature of the outer zones. The coarse-grained textures of pegmatites tend to be located in the central portions of pegmatite bodies, where the rock fabric lacks much of the anisotropy that is evident in the outer zones. In order to grow exceptionally large crystals of feldspars and quartz from melt, one of two conditions must be met: (1) either the time frame of crystallization must be exceedingly long (i.e., the rate of cooling must be exceedingly slow), such that a large fl ux of Al and Si can migrate even at their exceedingly low rates of diffusion through viscous granitic melt, or else (2) the viscosity of the melt must be lowered substantially by the accumulation of fl uxing components and excess alkalis, so that a large fl ux of Al and Si can diffuse to growing crystal surfaces in the (rapid) time frame of magmatic cooling. Among the two choices, the effects of increased fl uxes appear to be the most likely based on the calculated cooling histories of model pegmatite dikes. The problem of low fl ux content in the bulk compositions of pegmatite-forming magmas can be resolved by the process of constitutional zone refi ning (CZR), in which fl uxes and other quartz-feldspar incompatible elements are enriched in a boundary layer of melt adjacent to growing crystal surfaces (London 2008). Pegmatite crystallization at ~ 450°C provides the ideal environment for CZR to operate. At this condition, the rate of crystal growth is maximal (Swanson 1977; Fenn 1977), and the high viscosity of the bulk granitic melt prevents the back-diffusion of excluded components. Flux-rich boundary layers have been quenched even in the chemically evolved (lower viscosity) liquid composition of the hydrous Macusani obsidian at 450°-500°C and 200 MPa (London et al. 1989). The accumulation of fl uxing components of B, P, and F in the boundary layer liquid leads to a substantial increase in the solubility of H2O (London 2009). Suppression of aqueous vapor separation is the 3ASOCIACIÓN GEOLÓGICA ARGENTINA, SERIE D, PUBLICACIÓN ESPECIAL Nº 14 (2011) key to pegmatite formation, because increasing H2O lowers the viscosity of silicate melt, which enhances the diffusion of Al and of Si. The boundary layer liquids that have been documented in experiments are identical in all important respects to crystal- rich fl uid inclusions found in minerals from some pegmatite localities (e.g., Tanco, Manitoba: London 1986). The experimentally-produced fl ux-enriched boundary layer liquids, like the natural inclusions, are alkaline, Na-rich, and contain upwards of 15-20 wt% H2O (i.e., in excess of 80 mol% H2O). At 500°C and 200 MPa, a liquid of this approximate composition possessed a viscosity of ~ 10 Pas (London 1986, 2008). An experimental analog to this composition at 800°C and 200 MPa transports normally slow-diffusing Si at a fl ux (mass/volume) that is 107 times greater that an equal volume of H2O fl uid and at a rate (distance/ time) that is 107 times greater than H2O-saturated haplogranite liquid (DSi ~ 2.5*10-15 m2s-1) without other fl uxing components (London 2009). Hence, a fl ux-rich boundary layer liquid resolves the problems of low bulk concentrations of fluxes, high bulk viscosity of granitic liquid at low temperatures, and commensurately, low rates of diffusion for Al and Si that would prohibit the formation of large monophase crystals of quartz and feldspars. REFERENCES Anderson, G.M. & Burnham, C.W. (1983). Feldspar solubility and the transport of aluminum under metamorphic conditions. Am. J. Sci. 283-A: 283-297. Cline, J.S. & Bodnar, R.J. (1991). Can economic porphyry copper mineralization be generated by a typical calc-alkaline melt?. J. Geophy. Res. 96 (B5): 8113-8126. Fenn, P.M. (1977). The nucleation and growth of alkali feldspars from hydrous melts. Can. Mineral. 1:, 135-161. Fenn, P.M. (1986). On the origin of graphic granite. Am. Mineral. 71: 325-330. Jahns, R.H. & Burnham, C.W. (1969). Experimental studies of pegmatite genesis: I. A model for the derivation and crystallization of granitic pegmatites. Econ. Geol. 64: 843-864. Kilinc, I.A. (1969). Experimental metamorphism and anatexis of shales and graywackes. Ph.D. Thesis. Pennsylvania State University, University Park, Pennsylvania, U.S.A. 191 p. London, D. (1986). The magmatic-hydrothermal transition in the Tanco rare-element pegmatite: evidence from fluid inclusions and phase equilibrium experiments. Am. Mineral. 71: 376-395 London, D. (2008). Pegmatites. Sp. Pub. 10, Can. Mineral. 368 p. London, D. (2009). The origin of primary textures in granitic pegmatites. Can. Mineral. 47: 697-724. London, D., Morgan, G.B., VI, & Hervig, R.L. (1989). Vapor-undersaturated experiments in the system macusanite-H2O at 200 MPa, and the internal differentiation of granitic pegmatites. Contrib. Mineral. Petrol. 102: 1-17. Morgan, G.B., VI & London, D. (1987). Alteration of amphibolitic wallrocks around the Tanco rare- element pegmatite, Bernic Lake, Manitoba. Am. Mineral. 72: 1097-1121. Morgan, G.B., VI & London, D. (1989). Experimental reactions of amphibolite with boron-bearing aqueous fluids at 200 MPa: Implications for tourmaline stability and partial melting in mafi c rocks. Contrib. Mineral. Petrol. 102: 281-297. Stilling, A., Černý, P., & Vanstone, P.J. (2006). The Tanco pegmatite at Bernic Lake, Manitoba. XVI. Zonal and bulk compositions and their petrogenetic significance. Can. Mineral. 44: 599-623. Swanson, S.E. (1977). Relation of nucleation and crystal-growth to the development of granitic textures. Am. Mineral. 62: 966-978. ASOCIACIÓN GEOLÓGICA ARGENTINA, SERIE D, PUBLICACIÓN ESPECIAL Nº 14: 5-7 (2011) PEARLS OF WISDOM GLEANED FROM MY MENTORS: WAYNE BURNHAM, FRANK TUTTLE AND DICK JAHNS Robert F. Martin Earth and Planetary Sciences, McGill University, Montreal, Canada; robert.martin@mcgill.ca Key words: granite, pegmatites, rock–fluid interaction, element mobility, metasomatism, ichors. INTRODUCTION Early on in my professional career, as an under- graduate student, in fact, I developed a strong interest in the mineralogy and petrology of felsic igneous rocks. So much so, that I applied to do graduate-level work at a university where “big names” had made the place a veritable mecca in the study of granites and granitic pegmatites. It is nothing short of providential, career-wise I mean, that I was accepted to attend The Pennsylvania State University. There, I took courses from Wayne Burnham and Frank Tuttle, both leaders in their respective fi elds; Dick Jahns was in the pic- ture, but rather remotely for me, as he was the Dean of the College of Mineral Sciences, and not involved in teaching activities, at least not to incoming M.Sc. candidates. LESSONS LEARNED FROM C. WAYNE BURNHAM Professor C. Wayne Burnham was a no-nonsense kind of guy in class as well as out. I remember being very nervous in my one-semester seminar course en- titled Hydrothermal Mineralogy in which, as the name implies, we focused on the power of hydrothermal fl uids to change the mineralogy of solid rocks. In class, students sat around a large oval table with the master; two or three papers had been assigned to all in order to prepare the week’s seminar, and a student among the twelve or so was chosen at random, on the spot, to distill the main message for all present. I survived, and do remember discussing metasomatic overprints in mineralized granites and in kimberlites in the mantle. Prof. Burnham was a very innovative experi- mentalist, who took great pride in his inventions. He seemed able to address any challenge associated with high-pressure experimentation in silicate systems. I remember discussions on the solubility of minerals, for example albite, the P–V–T properties of H2O at high pressure, the solubility of H2O in felsic magmas, and experimentation with mixed H2O–CO2 fl uids. He clearly had carried out polythermal experiments on granite – H2O and granite – H2O – HCl, mostly with applications to porphyry-copper deposits. In the course, nothing specifi c was presented on the role of an aqueous fl uid phase during the crystallization of granitic pegmatites. There was no hint of what was to come fi ve years later, when the high-impact-factor paper by Jahns and Burnham was published in 1969. Other problems were more fascinating than the origin of granitic pegmatites! Professor Burnham’s fame rests not only on his experimental prowess, but also on his classic work on the high-temperature skarns at Crestmore, California, probably the source of much of his early inspiration on element mobility in a thermal gradient involving a mixed H2O–CO2 fl uid phase. Incidentally, wasn’t the title of his course a great one??? LESSONS LEARNED FROM O. FRANK TUTTLE Whereas C. Wayne Burnham was not discreet about his prowess in the lab, Orville Frank Tuttle, also an experimentalist, was completely the opposi- te. Perhaps for this reason, they had no use for each other. Professor Tuttle became an important person in my professional life very late in his career. He retired prematurely owing to ill health two years before I defended my Ph.D., and was not even present at my defense. However, Wayne Burnham was brought in to grill me! Course work with Frank Tuttle focused on sys- tematic presentations of the phase equilibria along the binary joins in the granite system, then building up to the ternary and quaternary systems. Imagine an entire semester of lectures on “Petrogeny’s Residua”, the system NaAlSiO4 – KAlSiO4 – SiO2 – H2O, its mi- neralogical aspects and the petrological applications! We had classes on the  – transition in quartz, the phase diagram for the system Ab – Or, the ramifi ca- tions of the hypersolvus and subsolvus textures in granites and nepheline syenites, and discussions on fractionation in the silica-undersaturated and silica- 6 PEARLS OF WISDOM GLEANED FROM MY MENTORS: WAYNE BURNHAM, FRANK TUTTLE AND DICK JAHNS oversaturated parts of the system. The main textbook used in the course was the bible of granite petrologists, then as now, GSA Memoir 74 by O.F. Tuttle and his mentor in the experimental approach, Norman Levi Bowen, Canada’s lasting gift to petrology. The strong message in the course was that there was no doubt at all, granites are products of the crys- tallization of felsic magmas. We did read up on the heated and epic debates involving Bowen, an expe- rimentalist, on one side, and fi eld-oriented types like Sederholm and Read, working in Archean terranes of northern Europe, on the other. We thus learned about the mythical “ichors” that Sederholm believed could transform quartzofeldspathic sedimentary units into granitic rocks without going through a melt stage. In class, the case was cut-and-dried... granites truly are igneous. In private discussions, however, Prof. Tuttle stressed upon me the importance of keeping a very open mind about the matter. Basically, he felt that people of the caliber of Sederholm, arguing for “granitization” in the deep crust, were probably not completely naive. He was working at the time with a postdoctoral fellow named William C. Luth, who was fi nding rather startling results on the solubility of H2O in granitic magmas at elevated pressure, and on the solubility of the magma in the coexisting H2O. Could such fl uids in the deep crust represent the ichors? I do believe so. Although Frank Tuttle was very much an ex- perimentalist, he went to the fi eld every summer to interact with students working on granite-related projects. For example, he came to visit me in New Brunswick, and became familiar with my embryonic ideas that there were granites related to orogenic suites, and other granites related to anorogenic suites that had nothing directly to do with an orogeny. If he had not been forced to retire early, I can see that we could have gone on to defi ne O- and A-type granites. Remember that all this was going on just before the plate-tectonic revolution and before the birth of the “genetic alphabet” of the Australian school in the late sixties and the concept of A-type granites in the late seventies. Frank had exceptional insight into the workings of petrological systems, be they SiO2-oversaturated or not, and was in the same league as Bowen. He was aware that rocks in Petrogeny’s Residua formed from magmas that are not anhydrous. What is the role of H2O once that magma freezes? He knew that most granites contain microcline, but he also knew that microcline does not crystallize from a magma. He was fascinated by what goes on in the subsolidus chapter of the history of a granite body. He suggested that I work on the alkali feldspars for a Ph.D. thesis, strictly from the point of view of subsolidus phenomena. His main message to all his students? Rocks are like a book, and threads of the story are contained in the rock-forming minerals. Learn to read the minerals and to interpret their textural attributes, and you will be able to unravel the story. LESSONS LEARNED FROM RICHARD H. JAHNS With the move of Frank Tuttle and Dick Jahns to Stanford University, and Peter Wyllie (also my professor) to the University of Chicago, the power- house at Penn State lost its superstars. At Stanford, Dr. Tuttle was my main advisor for a year or so, then was forced to retire owing to ill health. I became directly involved with Dick Jahns for the next two years as I worked on my Ph.D., and for two years after that as a postdoctoral fellow making use of the excellent equipment in the so-called “bomb lab”, much of it brought in from Penn State. At Stanford, Dick Jahns did minimal traditional teaching. He was, after all, Dean of the School of Earth Sciences, and as such, responsible for ensuring the well-being of the school. Dick was very affable, and a real go-getter. As Dean, he was active in fund-raising, a vital activity in this high-level private university (i.e., no operating grant from the state or federal govern- ment). I am sure that his annual one-semester course offering, run in his large living room at home in the evening, was all that he could handle in the area of teaching. But it was a very popular course, with snacks and beer served at the end of the evening to the appre- ciative twenty or so attendees. Each week, there was an identifi ed theme, and students were expected to do most of the talking; the atmosphere was MUCH more relaxed than in Wayne Burnham’s seminars at Penn State! Then Dick would wade in toward the end of the evening’s session to summarize the discussion, and give us his own perspective on things. It was a great experience for me personally, because he used to pick on me rather often to explain to others the fi ner points having to do with mineralogy and textures. The topic of one seminar was a rectangular table in the center of the living room; it was a slab of the Chelmsford granite showing an aplite dike cross-cutting the gra- nite slab diagonally, and discoloring it rather subtly. At both contacts, it was clear that the melt had begun to crystallize as a pegmatite, with nascent tapering crystals oriented inward, then it abruptly changed to crystallize as an aplite. It was an excellent example to inspire a discussion on nucleation and growth of the nuclei and on the various ways of explaining the aplitic texture. I can remember trying to pin down Dick Jahns on exactly what he had in mind to explain the strong compositional contrasts between the hanging wall and the footwall of some pegmatites that he had descri- bed from Southern California. He kept talking about the solubility of melt constituents in a free aqueous fl uid, and the compositional dependence of the solute carried by the supercritical fl uid on temperature, but with well-chosen words, without presenting hard 7ASOCIACIÓN GEOLÓGICA ARGENTINA, SERIE D, PUBLICACIÓN ESPECIAL Nº 14 (2011) data. He alluded to “little red wagons”, presumably aqueous bubbles, that were circulating in the magma and progressively causing the magma to “dispropor- tionate” into a sodic zone that represented the “com- positionally quenched” melt depleted in K, formed at the high-temperature end of a thermal gradient, and a potassic zone, forming in the low-temperature part of that gradient, and more enriched in the incompatible elements. We of course were fully aware of and discus- sed the interesting paper that Jahns had coauthored with Frank Tuttle on this model. I stayed on at Stanford for two years after my Ph.D. In those two years, I was building up my portfolio of original publications, on order–disorder relations in the sodic and potassic feldspars, as mo- nitored by X-ray diffraction and infrared absorption spectroscopy, and on boron in K-rich feldspars. I tackled and published on the alkali feldspar solvus at various pressures. I carried out a determination of the melting relations of a sample of graphic granite from Southern California, and one of a high-fl uorine topaz- bearing leucogranite from Cornwall, U.K. Dick was particularly interested in my work on polythermal experiments at elevated (crustal) pressures, which I will summarize at this conference. He is the one who inspired me to do this work, and was fascinated to see that I systematically found K and Na to be very mobile in an aqueous fl uid (K > Na) in a temperature gradient. After I had left Stanford, he provided me with a some unpublished data from experiments done years before at Penn State, probably by Wayne Burn- ham or W.C. Luth. I deemed my results publishable, and I was hoping for a copublication, Martin & Jahns. But it soon became clear that Dick was suppressing my publication of those “vapor-transport” results. Also relevant to this pattern of behavior was his reticence to publish his own work, specifi cally Parts II, III and IV of the Jahns–Burnham model, i.e., the long-awaited raw data backing up the model. He specifi cally told me that Parts II and III were already written in 1969, and Part IV was at “an advanced conceptual stage”. When I embarked on a two-year stint as a post-docto- ral fellow on a project directly relevant to his model, why did he not provide me with anything??? Dick Jahns was a geopolitician, whose inte- ractions were always interspersed with jokes. One wondered where he had learned his latest “Did you hear about the poor guy who...........”? He loved to play practical jokes on unsuspecting colleagues. He was fun to be with, in class and in the fi eld. He was a consumate communicator, and was very successful at what he did. He rose to the top, and not only in the area of “pegmatology”; in fact, he is better known in the area of engineering geology. In his communi- cations about granitic pegmatites, in his course, for example, he allowed the audience to believe that he had done a lot of experimental work in his career. In fact, all of that was mirrors and smoke screens, I’m afraid. Dick Jahns was very much a fi eld man who had learned a tremendous amount about crystal growth and phase equilibria in the granite system “by osmo- sis”, owing to close contacts over many years with top-notch experimental petrologists working in the same institutions, Penn State and Stanford. His model is not without merit, as aqueous fl uids are clearly an important part of the story, but not in the way that he conceptualized it in the Jahns–Burnham model, in my opinion. CONCLUSIONS Just what is the role of the orthomagmatic fl uid phase in the evolution of granitic pegmatites? I do believe that at the magmatic stage, in those pegmatites formed in an epizonal environment, such a fl uid can collect in miarolitic pockets. I like the explanations of Dick Jahns about the individuality of such pockets, about pocket rupture due to implosions or explosions, and the formation of gem-quality crystals from this orthomagmatic fl uid. I much prefer David London’s explanations of the textural zonation of granite bodies to those of my mentor. In view of my own results on polythermal experiments, I honestly never did belie- ve that they were very relevant to the compositional zonation of individual bodies of granitic pegmatite. Rather, I apply my results to lower crust – mantle inte- ractions, and important metasomatism going on there to fertilize the crust undergoing distension. It seems clear that except for quartz, the minerals that we study in granites and pegmatites are largely pseudomorphs of the minerals that the magma produced. ASOCIACIÓN GEOLÓGICA ARGENTINA, SERIE D, PUBLICACIÓN ESPECIAL Nº 14: 9-12 (2011) INTRODUCTION Minerals of the tourmaline group (schorl, dravite > elbaite > foitite, rossmanite, liddicoatite > olenite, uvite, magnesiofoitite, feruvite, buergerite) are typical accessory minerals in many granitic pegmatites. They originated in different stages of pegmatite evolution from primary magmatic to late hydrothermal; moreover, tourmaline also occurs in pegmatite exocontacts. High compositional variability of tourmaline, its refractory properties and abundance of tourmaline in various zones of the individual pegmatites, make tourmaline-group minerals excellent and widely used indicators of geochemical evolution from magmatic to hydrothermal stage and of contamination from host rocks as well. However, crystal-structural constraints, which also control chemical composition of tourmaline, are only poorly known. TEXTURAL AND MORPHOLOGICAL TYPES OF TOURMALINE Tourmaline occurs in many textural and morphological types, which manifest their origin in various stages of pegmatite evolution: (i) primary tourmaline crystallized in (ia) various textural- paragenetic units of massive pegmatite and in (ib) pockets; (ii) secondary (subsolidus) tourmaline replacing early minerals (e.g., cordierite, biotite, garnet, Fe,Mn,Mg-phosphates); (iii) hydrothermal tourmaline originated on late fractures within pegmatite or as a very late mineral in pockets; (iv) exomorphic tourmaline on exocontact or in enclaves of host rocks. Size and morphology of crystals and aggregates in the individual textural types are highly variable from large euhedral crystals, up to several m long, to very fi ne-grained aggregates or graphic intergrowths with quartz. In micro-scale (thin sections, BSE images), tourmaline textures are highly variable from homogeneous (ia), (ib), to simply zoned (ia), (ib), (iv), oscillatory zoned (ib), (iii), irregularly to patchy zoned (ia), (ii), (iv). Also late microscopic veining in rather homogeneous primary tourmaline is locally common (ia). High variability in macro- and micro- scale is behind the scope of this presentation; hence, only typical cases were given. CRYSTAL CHEMISTRY OF TOURMALINE The generalized tourmaline structural formula: XY3 Z6(T6O18)(BO3)3V3W, where the common ions at each site are: X = Na1+, Ca2+ and vacancy; Y = Fe2+, Mg2+, Al3+, Li1+ and Fe3+; Z = Al3+, Fe3+ and Mg2+; T = Si4+, Al3+, B3+ ; B = B3+; V = OH1- and O2-; and W = F1-, O2- and OH1-. Also other cations are signifi cant in some granitic pegmatites (Bi3+, Pb2+, Cu2+, Zn2+, Mn2+, Mn3+, Ti4+). Important heterovalent coupled substitutions include: (1) XR1+ + R2+ = X + R3+ , (2) XR1+ + R3+ = XCa + R2+, (3) Y2R2+ = YLi1+ + YAl3+, (4) + R2+ + OH1- = R3+ + O2- along with several homovalent substitutions e.g., (5) Fe2+ = Mg or (6) OH1- = F1-. Numerous substitutions enable high variabitity of chemical compositions and thus record compositional evolution of parent medium as well as a change in PTX conditions. GEOCHEMICAL TYPES OF TOURMALINE- BEARING PEGMATITES Tourmaline, typically Altot > 6 apfu, occurs in pegmatites varying from abyssal, muscovite, rare- element to miarolitic class; hence, in a wide range of PT conditions; however, a peraluminous character of parental pegmatite is almost exclusive (London 2008). Also the degree of geochemical fractionation of parental pegmatites is highly variable from very primitive compositions to extremely evolved Li,Cs-rich pegmatites. Compositional evolution in tourmaline was studied in detail in various complex pegmatites and slightly different trends in the lepidolite, elbaite, spodumene and petalite subtypes, respectively, were revealed. In contrast, compositional TOURMALINE IN GRANITIC PEGMATITES Milan Novák Department of Geological Sciences, Masaryk University, Kotlárská 2, 611 37 Brno Czech Republic; mnovak@sci.muni.cz Key words: tourmaline, compositional evolution, geochemical types, crystal-structural constraints, granitic pegmatites 10 TOURMALINE IN GRANITIC PEGMATITES trends in tourmaline from primitive Mg-enriched and Li-poor pegmatites, and from Li-poor and extremely Al-rich abyssal pegmatites are less-known as well as the composition of Ca,Mg,(Fe)-enriched and locally relatively Al-poor tourmaline from exocontacts or from evidently contaminated pegmatites. Only recently, tourmalines with Altot ~4-6 apfu were discovered in pegmatites. They include several very distinct geochemical and genetic types such as: intragranitic NYF pegmatites from K,Mg-rich syenogranites of the Trebíc Pluton, Czech Republic (Ca,Ti,Fe3+-enriched dravite-schorl; Novák et al. accepted; Fig. 1); miarolitic pegmatites with zeolites from the Vitosha Mnts., Bulgaria (schorl-buergerite-foitite); quartz-free, sodalite- nepheline-cancrinite pegmatite from the Cancrinite Hill, Bancroft, Ontario (Fe3+-rich schorl); highly contaminated granitic pegmatites cutting Fe-skarn at Vlast jovice and Mirošov, Moldanubian Zone, Czech Republic (schorl-feruvite, Novák & Kadlec 2010; Fig. 2). Disregarding evident dominance of peraluminous compositions, tourmaline with Altot < 6 apfu also occurs in pegmatites; nevertheless, low Al in tourmaline and parental pegmatite may be controlled by different factors: (i) metaluminous to alkaline composition of the pegmatite melt and (ii) contamination from the host rock. Hence, the elevated contents of Fe3+, Ti and Ca may stabilize tourmaline in such specifi c conditions (Novák et al. accepted). FIGURE 1. Composition of tourmaline from NYF pegmatites of the Trebíc Pluton (slightly modifi ed from Novák et al. accepted). a) Na-Ca-X-site vacancy plot, b) Al-Fe-Mg plot. Squires – allanite-type pegmatites, grey circles – euxenite-type pegmatites, solid circles – euxenite pegmatite Klu ov I. FIGURE 2. Composition of tourmaline from non-contaminated and contaminated pegmatites cutting Fe-skarn in Vlast jovice. (slightly modifi ed from Novák & Kadlec 2010). a) Na-Ca-X-site vacancy plot, b) Al-Fe-Mg plot. Grey circles – pegmatites from gneisses, open circles – pegmatite on the contact of Fe-skarn and orthogneiss, solid circles – pegmatites cutting Fe-skarn including elbaite pegmatite. 11ASOCIACIÓN GEOLÓGICA ARGENTINA, SERIE D, PUBLICACIÓN ESPECIAL Nº 14 (2011) ROLE OF CRYSTAL-STRUCTURAL CONSTRAINTS AND THEIR SIGNIFICANCE FOR TOURMALINE COMPOSITION Role of short-range order and other crystal- structural constraints on tourmaline composition in granitic pegmatites are only exceptionally discussed. The crystal-structural studies (e.g., Hawthorne 1996, 2002, Bosi 2008) revealed that crystal-structural constraints (mainly short-range order) play a signifi cant role in tourmaline compositions (Table 1). For example, tourmaline with high Fe/Mg from pegmatite systems show three distinctive compositions controlled by activities of F and Li in a parental melt and by crystal-structural constraints as well. General chemical type of tourmaline W-site anion Stable short-range confi gurations Li-free tourmaline (OH)1- or F1- 3R2+ or R3+ + 2R2+ Li-free tourmaline O2- 3R3+ or 2R3+ + R2+ Li-bearing tourmaline (OH)1- or F1- 2Al3+ + Li1+ or Al3+ + 2Li1+ Li-bearing tourmaline O2- 3Al3+ TABLE 1. Stable short-range Y-site cation confi gurations for anions of different charge at the W site. In the rocks with low activities of F and Li (outer zones of complex pegmatites), tourmaline composition commonly tends to the formula (Novák et al. 2004): X(Na0.5 0.5) Y(Fe2+ 2Al) ZAl6 (BO3)3 TSi6O18 V(OH)3 W(O0.5OH0.5) foitite - oxy-schorl. In the rocks with high activity of F but low activity of Li (F-rich muscovite granites), tourmaline composition tends to the formula: XNa YFe2+ 3 ZAl6 (BO3)3 TSi6O18 V(OH)3 WF fl uor-schorl. In the rocks characterized by high activity of F and Li (intermediate zones of some complex pegmatites with Li-muscovite and lepidolite), tourmaline composition tends to the formula: XNa Y(LiFe2+Al) ZAl6 (BO3)3 TSi6O18 V(OH)3 WF Fe-rich fl uor-elbaite. These well-defined compositions strongly suggest signifi cant role of crystal-structural constraints on the tourmaline composition. In F-,Li-poor rocks, the composition is characterized by high vacancy in the X site, and signifi cant amount of O in the W site; the occupancy of the Y site is controlled by short-range requirements and the confi guration R2+- R2+- Al3+ is the most suitable (Table 1). High amount of F at the W site controls the X-site occupancy (high Na and low vacancy) and the confi guration at the Y site commonly tends to Y = 6 apfu (Fe2+- Fe2+- Fe2+). In rocks with of high activities of F and Li, the high content of F at W site controls the X site (high Na and low vacancy) and the confi guration in the Y site requires Y = 6 apfu, and it has, owing to incorporation of Li, the most stable confi guration (Li+- Fe2+- Al3+). The compositional variations in tourmaline from these granitic environments, which are characterized by very similar PT conditions and chemical composition (except for activities of Li and F), suggest signifi cant roles of Li and F. These elements not only enter their appropriate crystallographic sites (Y site and W site, respectively), but signifi cantly control confi guration in the Y site and occupancy in the X site. The chemical compositions exhibit combination of both geochemical and crystal-structural constraints. The fi rst one is marked by concentrations of Li and F; the second one signifi cantly controls occupancies and confi gurations at the X site, Y site and W site in tourmaline. Consequently, crystal-structural constraints should be considered as a signifi cant factor controlling chemical composition of tourmaline from granitic pegmatites and its stability as well. ACKNOWLEDGEMENTS This work was supported by the research project GAČR P210/10/0743. REFERENCES Bosi, F. (2008). Disordering of Fe2+ over octahedrally coordinated sites of tourmaline. Am. Mineral. 93: 1647-1653. Hawthorne, F.C. (1996). Structural mechanisms for light-element variations in tourmaline. Can. Mineral. 34: 123-132. Hawthorne, F.C. (2002). Bond-valence constraints on the chemical composition of tourmaline. Can. Mineral. 40: 789-797. London, D. (2008): Pegmatites. Sp. Publ. 10. Mineral Assoc. Canada. 368 pp. Novák, M. & Kadlec, T. (2010). Vlast jovice near Zruc nad Sázavou. Contaminated anatectic pegmatites and tourmaline-bearing granite- pegmatite system cutting Fe-skarn. In: Novák, M. & Cempírek J. eds.; Acta Mineral. Petrogr., Field Guide Series 6: 36-41. 12 Novák, M., Povondra, P. & Selway, J.B. (2004). Schorl- oxy-schorl to dravite-oxy-dravite tourmaline from granitic pegmatites; examples from the Moldanubicum, Czech Republic. Eur. J. Mineral. 16: 323-333. Novák, M., Škoda, P., Filip, J., Macek. I. & Vaculovi , T. (2011). Compositional trends in tourmaline from intragranitic NYF pegmatites of the Trebíc Pluton, Czech Republic; electron microprobe, Mössbauer and LA-ICP-MS study. Can. Mineral., in press. TOURMALINE IN GRANITIC PEGMATITES ASOCIACIÓN GEOLÓGICA ARGENTINA, SERIE D, PUBLICACIÓN ESPECIAL Nº 14: 13-16 (2011) GEOCHEMISTRY OF REE–RICH PEGMATITES FROM DIFFERENT TECTONO- MAGMATIC PROVINCES IN SOUTH PLATTE, CO, TROUT CREEK PASS, CO, KINGMAN AND AQUARIUS RANGE, AZ, NORTH AMERICA William Simmons1, Karen Webber1, Alexander U. Falster1, Sarah Hanson2 & TJ Brown1 1 Department of Earth and Environmental Sciences, University of New Orleans, New Orleans, LA 70148, US. §wsimmons@uno.edu, 2 Earth Science Department, Adrian College, Adrian, MI 49221, US. Key Words: REE-rich pegmatite, tectonic-setting, trace-element, South-Platte, Trout-Creek-Pass, Rare-Metals-pegmatite INTRODUCTION Pegmatites of the South Platte (SP), Colorado (CO), Trout Creek Pass (TCP), CO, Kingman (K) and Aquarius Range (AQ), Arizona (AZ) have distinctly different tectonic affi liations. Geochemically, pegmatites in these districts are very REE enriched. Each has a distinct mineralogical and geochemical signature. SOUTH PLATTE The SP Pegmatite District occurs within the Precambrian core of the Rocky Mountain Front Range in Jefferson County, CO. Located near the northern margin of the Pikes Peak Batholith, it is an extremely REE enriched pegmatite district containing over 75 pegmatites. All of the pegmatites occur as segregations within the parental granite rocks of the 1 Ga Pikes Peak Batholith. More than fi fty pegmatites cluster in a relatively small area of only about ten square kilometers. In this area, reddish granite forms the outer zone of the batholith and conforms to the curving contact of the batholith. The pegmatites are large, complex, nearly vertical bodies with a roughly circular to elliptical shape in plan with well-developed concentric zoning. Their diameters or long axes range from less than a meter to almost a hundred meters in length. They have extraordinarily well-developed internal zonal structure and contain abundant rare-earth minerals, zones of massive fl uorite, and hematite and albite replacement zones. Strongly enriched yttrian fl uorite forms large masses along the core margin of the White Cloud and several other pegmatites. Almost a ton of REE concentrates were recovered from the White Cloud pegmatite alone. Samarskite-(Y) (Fig. 1) is a major sink for the high fi eld strength elements Y, Nb, HREE, Ta and U; and large concentrations were mined from the replacement units of a number of pegmatites. Several hundred tons of samarskite-(Y) were mined from the Quartz Knob pegmatite. Some masses exceeded 60 cm in maximum dimension. Yb enrichment is exceptionally high in the Little Patsy pegmatite where samarskite- (Yb) was discovered. Columbite group minerals are much less abundant than samarskite-(Y) but are found in a few pegmatites (Fig. 1). Gadolinite-(Ce&Y), thalenite-(Y), synchysite-(Y&Ce), and bastnaesite-(Ce) occur in the fl uorite replacement unit of the White Cloud pegmatite, and xenotime-(Y) is abundant in the yttrian fl uorite unit of the Big Bertha pegmatite FIGURE 1. Ta/Ta+Nb vs. Mn/Mn+Fe for ferrocolumbite and samarskite-(Y) in SP & TCP. (Fig. 2). HREE- and Hf-rich zircons in large crystal aggregates up to 15 cm across are abundant in the core margin of the Luster pegmatite and are found in lesser amounts in most other pegmatites. Large anhedral masses of allanite-(Ce) up to 10 cm across occur in the intermediate zones of a number of pegmatites. In terms of Hf, Mn, Ta and Yb enrichment, the Patsy and the Luster are the most evolved pegmatites (Figs. 1, 3).Within the district, a geographical separation exists between pegmatites enriched in LREE vs. HREE. Composite core pegmatites in the southern part of the district contain ‘allanite’ and are LREE enriched. The 14 GEOCHEMISTRY OF REE–RICH PEGMATITES FROM DIFFERENT TECTONO-MAGMATIC PROVINCES IN SOUTH PLATTE, NORTH AMERICA fl uorine-rich quartz-core pegmatites, located in the northern portion of the district, are HREE enriched, containing mainly ‘samarskite’. The separation is related to fl uorine complexing of HREE over LREE. SP is a classic NYF pegmatite district (Simmons et al. 1987). TROUT CREEK PASS The TCP pegmatite district is located in the Mosquito Range, Chaffee County, CO. It contains only four pegmatites that were mined for feldspar, but all contain notable concentrations of REE. The district is associated with the catazonal, orogenic, 1.7 Ga Denny Creek pluton of the composite Routt Plutonic Suite, emplaced during the Boulder Creek Orogeny. Subsequent to this orogenic event, mesozonal granitoids of the Berthoud Plutonic Suite (Silver Plume equivalents) were emplaced as part of the Proterozoic anorogenic 1.4 to 1.45 Ga event. In the Mosquito Range, the Denny Creek pluton consists dominantly of foliated biotite granite, with minor quartz monzonite and a foliated quartz monzodiorite in the southern area. Numerous pegmatites ranging in size from one to several hundred meters are scattered throughout the district. The four largest include the Yard, the Clora May, the Crystal No. 8, and the Tie Gulch. They are structurally well-zoned with a graphic granite wallzone, a composite quartz-microcline core and superimposed albite-rich replacement units. The pegmatites are notably enriched in HREE, Nb, Y and Ti, and depleted in F. Polycrase-(Y) (Fig. 1), found exclusively in the albitic replacement units, is the dominant HREE, Nb and Ti mineral; and monazite- (Ce) and allanite-(Ce), which are found only in the cores, are the dominant LREE minerals in the district. Very minor columbite-(Fe) is found in the core (Fig. 1). The intra-pegmatite separation of the LREE and HREE within these pegmatites cannot be related to fl uorine complexing as there is virtually no fl uorine in these pegmatites. The presence of ‘polycrase’ instead of ‘samarskite’, as in SP, is related to the stability of ‘polycrase’ over ‘samarskite’ in a F-depleted, high Y, Ti, Nb, HREE environment. Here the separation of LREE and HREE appears to be related to late-stage enrichment of HREE caused by early crystallization of the LREE minerals allanite-(Ce) and monazite-(Ce) in the pegmatite cores. Even though the TCP district is associated with an orogenic event, the mineralogy of the pegmatites is distinctly NYF in character (Hanson et al. 1992). KINGMAN AND AQUARIUS RANGE Five pegmatites from the Basin and Range province near Kingman, AZ have been recently examined. They include the Kingman pegmatite, located in the Cerbat Range (CR) just north of Kingman, AZ, and the Rare Metals, and three Wagon Bow pegmatites located in the Aquarius Range (AQ) about 100 km SW of Kingman. The ranges were formed as a result of block faulting during Miocene extension of SW North America. All pegmatites are hosted in Paleoproterozoic granitic rocks of the Mojave terrane. Ages of the Cerbat plutons are generally contemporaneous with the juxtaposition of the Mojave and Yavapai terranes (1.740 – 1.720 Ga) (Duebendorfer et al. 2001). The AQ Range granites lie within the Boundary Zone between the Mojave and Yavapai terranes and are slightly younger, and associated with the subsequent docking of the sutured Mojave and Yavapai terranes to North America during the Yavapai Orogeny (1.710 – 1.680 Ga). The Boundary Zone is isotopically mixed and marked by both syn- and post-collisional modifi cation (Duebendorfer et al. 2001). All of the pegmatites appear to have been emplaced after docking of the sutured Mojave and Yavapai terranes with North America (Yavapai orogeny, 1.710-1.680 Ga). The cross-cutting nature of the Kingman pegmatite suggests tha it is younger and not genetically related to the inferred older ~1.682 Ga host Cerbat granite. However, the Wagon Bow and FIGURE 3. Hf enrichment in SP & TCP zircon.FIGURE 2. Chondrite normalized REE content in various SP fl uorite samples. 15ASOCIACIÓN GEOLÓGICA ARGENTINA, SERIE D, PUBLICACIÓN ESPECIAL Nº 14 (2011) Rare Metals pegmatites, which are segregations in the younger AQ Range granitic dikes, appear to be genetically related to their host granites. The pegmatites are all zoned with border (only Kingman), wall, and intermediate zones and composite quartz-microcline cores. All are REE enriched containing monazite-(Ce), allanite-(Ce), bastnaesite-(Ce), ± polycrase-(Y) and euxenite-(Y). Like the TCP pegmatites they contain virtually no fl uorine. The Kingman pegmatite contains abundant LREE minerals, but Nb- and Ta-phases are notably absent. In the Rare Metals pegmatite, small quantities of Nb and Ta are present in sporadic euxenite-(Y) and polycrase-(Y) in replacement units. Here as in TCP, early ‘allanite’ and ‘monazite’ crystallization removed LREE, fractionating HREE into late replacement units which crystallized ‘polycrase’ or ‘euxenite’. The Rare Metals pegmatite contains rare beryl and muscovite. The Wagon Bow pegmatites appear to be less evolved with lower concentrations of Nb, Ta, and REE. The Kingman pegmatite shows strong enrichment of Nd with the fi rst reported occurrence of “allanite-(Nd)” as crude crystals and anhedral masses up to 20 cm across. GEOCHEMISTRY Rare earth element chondrite normalized plots are shown in Figure. 4a-c. SP is distinctly more enriched in total REE than TCP or K-AQ. SP and K-AQ have similar slopes with LREE enrichment but SP is overall more enriched in LREE. The Eu anomalies are prominent in SP and K-AQ, but less pronounced in TCP. The prominent Yb enrichment in some SP pegmatites is also seen in the SP granitic rocks as a positive Yb anomaly. TCP has a prominent positive Gd anomaly, but Gd enrichment in the pegmatites was not noted. The tectonic discriminant Rb vs. Y+Nb plots show the expected within plate (WP) signature for SP (Fig. 5a); TCP falls along the boundary of syn- collisional, volcanic arc (VA) and WP (Fig. 5b). The hybrid character of TCP is further shown in Fig. 5c on the Nb-Y plot. The K-AQ also has a hybrid signature plotting along VA and WP boundaries (Fig. 5d). Spider diagrams (rock/MORB) are shown in Figure 6. SP shows strong depletion in P, Ba, and Ti and enrichment in Rb, Th, Hf and Yb. TCP shows strong enrichment in Th and Ce and moderate depletion in P and Ti. K-AQ shows depletion in P, Ti, and Ba, and enrichment in Rb, Th, and Ce. These features are consistent with the SP system having formed from partial melting of depleted lower crust or extreme differentiation of upper mantle melt. TCP granitic rocks show mixed tectonic signatures that appear to be the result of postcollisional melting of mixed sources from the Boulder Creek Orogeny or the Silver Plume anorogenic event. New dates are needed to properly assess the timing. K-AQ granite-pegmatites also show mixed tectonic signatures which refl ect the complex Paleoproterozoic tectonic setting. The system shows within plate, subduction and volcanic FIGURE 4. Chondite normalized REE content of: a) SP, b) TCP, c) K-AQ granitic rocks FIGURE 5. Rb vs. Nb+Y tectonic discrimination diagrams for: a) SP, b) TCP, d) K-AQ; c) TCP Nb vs. Y. WPG-within plate, VAG-volcanic arc, syn-COLG-syncollisional, ORG-ocean ridge, granites. 16 GEOCHEMISTRY OF REE–RICH PEGMATITES FROM DIFFERENT TECTONO-MAGMATIC PROVINCES IN SOUTH PLATTE, NORTH AMERICA arc affi nities. This variability is attributed to early Proterozoic rifting which produced crust of both attenuated within plate crust and juvenile volcanic arc composition in the Boundary Zone (Duebendorfer et al. 2001). Subsequent remelting of this crust during and after the Yavapai Orogeny produced granites with complex hybrid compositions that are the result of the relative contributions of the diverse rifted crustal material. All REE-rich pegmatites are not created equal. REFERENCES Duebendorfer, E.M., Chamberlain, K.R. & Jones, C.S. (2001). Paleoproterozoic Tectonic History of the Cerbat Mountains, northwestern Arizona: Implications for crustal assembly in the southwestern United States. GSA Bulletin 113 (5): 575-590. Hanson, S.L., Simmons, W.B., Webber, K. L., and Falster, A.U. (1992) Rare-Earth-Element Mineralogy of Granitic Pegmatites in the Trout Creek Pass Pegmatite District, Chaffee County, Colorado. Can. Mineral. 30: 673-686. Simmons, W.B., Lee, M.T., and Brewster, R.H. (1987): Geochemistry and evolution of the South Platte granite-pegmatite system, Jefferson County, Colorado. Geoch. et Cosmoch. Acta 51: 455- 471. FIGURE 6. Spider diagrams, rock/MORB, for: a) SP, b) TCP, c) K-AQ granitic rocks ASOCIACIÓN GEOLÓGICA ARGENTINA, SERIE D, PUBLICACIÓN ESPECIAL Nº 14: 17-20 (2011) INTRODUCTION The Eastern Brazilian Pegmatite Province is known world-wide for its gemstones and occurrences of the minerals of Li, for example spodumene, elbaite, lepidolite, petalite and amblygonite. Its geographic distribution overlaps the huge Late Pre-Cambrian granitic magmatic arc of the Araçuaí Fold Belt, in the states of Minas Gerais and Bahia (Fig. 1). The magmatic arc comprises syn-, late- and post- tectonic intrusive bodies varying from tonalites to syenogranites, associated with metasedimentary and low- to high-grade metamorphic rocks, in the eastern and western portions of the magmatic arc, respectively. The pegmatites of the Salinas–Araçuaí belt [District A] belong to the LCT family (Li subclass), and cut mainly metasedimentary country- rocks and S-type granites. Pegmatites of the NYF family, in the Medina – Pedra Azul area [District B], are hosted by leucocratic equigranular and mesocratic porphyritic granites. The granitic country-rocks have abundant microcline megacrysts. They are considered calc- alkaline, with an overall syenogranitic composition (metaluminous I-type granites). In these rocks, Ba reaches 1000 ppm, Na2O/K2O varies between 0.8 and 3.0, and the lineage is 4a according to zircon morphology. The most outstanding rare-element minerals in pegmatites of District A includes: petalite, lepidolite, amblygonite, beryl, spodumene, variety “kunzite”, triphylite, pollucite, colored tourmaline crystals, cassiterite and columbite-group minerals (Ta > Nb). District A is the best-studied district in the Eastern Brazilian Pegmatite Province. The pegmatites of District B, which are the focus in this paper (Fig. 1), are located mainly in the poorer metasedimentary portion of the magmatic arc. The pegmatites belong to the REE subclass [beryl – columbite-(Fe) – phosphates – allanite – monazite] of the NYF family, allanite–monazite type. The 87Sr/86Sr THE DISTRICTS OF THE EASTERN PEGMATITE PROVINCE OF BRAZIL Nelson Angeli University of State of São Paulo, Rio Claro (SP), Brazil. 24-A Avenue, nº1515, postal code 13506-900: nangeli@rc.unesp.br Key words: Allanite-monazite type, REE subclass, Aquamarine, Topaz, NYF family, Magmatic Arc value of their I-type metaluminous source-granites varies between 0.7062 and 0.7132, which is lower than the values in the A District. Their K2O content is also higher (7.26–12.91%) than that of the granites in the A District (3.2–4.8%). The mean K2O (9%) and Rb (1200 ppm) values in muscovite and microcline indicate a lower degree of magmatic differentiation for the B District. The other districts (C: Governador Valadares – Juiz de Fora, D: Materlândia–Capelinha) consist of unzoned pegmatites that contains microcline, muscovite, biotite and some schorl, and belongs to the muscovite class of pegmatites according to Černý & Ercit (2005). GEOLOGICAL SETTING AND CHARACTERISTICS OF THE PEGMATITES The pegmatite bodies of District A were emplaced in the metasedimentary sequences, like Rio Doce, Macaúbas, Jequitinhonha and Salinas groups (Pedrosa Soares et al. 2001a). The country rocks display a medium- to high-grade metamorphism (amphibolite facies), and some of them are intruded by granites. Pegmatites in several small mines show precious to semiprecious gemstones, leading to the label Eastern Gemmology Province of Brazil proposed by Pinto & Pedrosa Soares (2001). Also present are phosphates with U–Th, rare metals and an enrichment in REE. To the south, the pegmatites of Governador Valadares – Conselheiro Pena and Juiz de Fora, Minas Gerais are unzoned and show a uniform texture (Muscovite class). The same occurs between Materlândia and Capelinha. These bodies present a simple mineralogy (microcline, muscovite, biotite, minor schorl and beryl). Microcline and muscovite are exploited as industrial minerals in ceramic pegmatites [Districts C and D] (Fig. 1). 18 THE DISTRICTS OF THE EASTERN PEGMATITE PROVINCE OF BRAZIL FIGURE 1. Geological sketch of the Eastern Brazilian Pegmatite Province and the proposed Districts (A, B, C and D). Adapted from Biondi (2003). The pegmatites from District B feature a late development of sodic plagioclase (Fig. 2), coexisting with zircon, magnetite and phosphates. The main accesory minerals comprise: topaz, beryl (in some places as large crystals or as the gemmy variety aquamarine), columbite-(Fe), zircon, apatite, rutile, titanite, fl uorite, amethyst, REE-rich allanite, radioactive monazite, samarskite and radioactive phosphates (goyazite, bobierrite and zwieselite), euxenite, autunite, herderite and fergusonite (Figs. 3, 4, 5). The alteration minerals are kaolinite, epidote, autunite and plumbogummite. The high degree of differentiation of the granites is shown in Figures 6, 7 and 8. The total concentration of the REE and FIGURE 2. Exposure of NYF granite pegmatite from Medina – Pedra Azul showing the late plagioclase (albite/oligoclase) located near the quartz core, together microcline and minor muscovite. The albite shows has the bladed habit known as «cleavelandite» (District B). FIGURE 3. Photomicrograph showing a zircon inclusion in biotite, associated with plagioclase and myrmekite; the pleochroic halos is due to inclusions of crystals containing radioactive elements (District B). 19ASOCIACIÓN GEOLÓGICA ARGENTINA, SERIE D, PUBLICACIÓN ESPECIAL Nº 14 (2011) FIGURE 4. Photo of beryl, variety aquamarine, close to the quartz core, in a small pocket in the Intermediate Zone exposed in an artisanal mine, Medina (District B) FIGURE 5. Photo of black crystals of columbite-(Fe) containing a small quantity of Ta, located at the contact of the Wall and Intermediate zones (District B). FIGURE 6. Plot of Na2O versus SiO2. Note: two samples showing muscovite and albitized muscovite-bearing granites indicate a late hydrothermal stage in rocks of District B. FIGURE 7. Chondrite-normalized REE patterns of rocks and minerals from the Medina – Pedra Azul district (left: samples correspond to granites close to Medina [MED 100B-110C]; right: samples from 10 km to the northeast of Pedra Azul [MEDF-MEDK4]). Normalization: Wakita et al. (1971). FIGURE 9. Triangular Si – Al – (Na + K) plot summarizing the evolutionary trend defi ned by the granitic pegmatites in District B, leading to topaz- and beryl-mineralized members. FIGURE 8. Tectonic affi liation of granitic rocks of the Medina – Pedra Azul district, in terms of the diagram of Pearce et al. (1984). Fields: Volcanic Arc Granite (VAG), Syn- Collisional Granite (syn-COLG), Intraplate Granite (WPG), and Ocean-Ridge Granite (ORG). 20 THE DISTRICTS OF THE EASTERN PEGMATITE PROVINCE OF BRAZIL the ratio Y/(REE + Y), increasing from 0.02 to 0.96, are consistent with a progressive geochemical fractionation of a granitic pegmatite-forming magma of NYF petrogenetic affi liation. The (La/Lu)CN value, 40, and the (La/Yb)CN value, 33, indicate a relatively low degree of fractionation of the LREE in comparison to the HREE. The normalized REE pattern varies in shape from uniformly tilted to fl at seagull-wing type, the latter quite similar to the REE pattern of the enclosing granites. A relative depletion in Eu (Fig. 7) is commonly developed. The erratic patterns developed in Figure 7 refl ect the presence of various REE-enriched minerals (e.g., zircon, allanite, titanite) in the pegmatites. A triangular Al – Si – (Na + K) plot shows an evolutionary trend of the pegmatites and their mineralized members, quite similar to the evolution of Caladão Granite (Ferreira et al. 2005), except that these only rarely contain garnet (Fig. 9). The granites in this district show a medium to high level of Al2O3, which varies between 11.8 and 17.8%, in comparison to the parental granites in District A, which contain more than 20%. All samples shown in Fig. 9, both of granite pegmatite and the country rocks, are from Medina. These new data for the Medina – Pedra Azul suite complement the previous information of Pedrosa-Soares (2001a, b) on the tectonic origin and the geochronology of the granitic pegmatites. A program of chemical analyses (mineral chemistry and REE), fluid inclusions, geothermometric and geobarometric studies are planned. CONCLUSIONS Granitic pegmatites of District B (Medina – Pedra Azul) suite are enriched in Be–Nb–P–REE–F–U+Th and classifi ed as belonging to the NYF family (Fig. 8), mainly intruded into biotite gneisses, which equilibrated at P = 3.5 kbar and T = 550C. The behaviour of the bodies is quite similar from north to the south, between Pedra Azul and Conselheiro Pena. The phosphates of the rare-earth elements in these NYF pegmatites are associated with late-stage replacement in portions of the pegmatites, and have arisen by pneumatolitic or hydrothermal alteration. In some artisanal mines, crystals of smoky quartz show structural defects owing to the presence of radioactive minerals in the vicinity. The relation of Rb versus (Y+Nb) shows a magmatic relationship of this NYF suite to continental arc granitoids (syn- to post-tectonic emplacement) for the parental rocks. ACKNOWLEDGEMENTS I acknowledge the anonymous referee for providing extensive help and constructive reviews in this last version. REFERENCES Biondi, J.C. (2003). Processos Metalogenéticos e os Depósitos Minerais Brasileiros. Editora Ofi cina de Textos, São Paulo: 528 p. Černý, P. & Ercit, T.S. (2005). The classifi cation of granitic pegmatites revisited. Can. Mineral. 43(6): 2005-2026. Ferreira, M.S.F., Fonseca, M.A. & Pires, F.R.M. (2005). Pegmatitos Mineralizados em Água-Marinha e Topázio do Ponto Marambaia, Minas Gerais: Tipologia e Relações com o Granito Caladão. Rev. Bras. Geociên. 35(4): 463-473. Pedrosa-Soares, A.C., Noce, C.M., Wiedemann, C.M. & Pinto, C.P. (2001a). The Araçuaí-West Congo Orogen in Brazil: an overview of a confi ned orogen formed during Gondwanaland assembly. Precambr. Res. 110: 307-323. Pedrosa-Soares, A.C., Pinto, C. P., Netto, C., Araújo, N. C., Castañeda, C., Achtschin, A.B. & Basílio, M.S. (2001 b). A Província Gemológica Oriental do Brasil. In: Gemas de Minas Gerais, Capítulo 1, Castañeda, C.; Addad, J. E. & Liccardo, A. (Organizadores): 16-33. Pinto, C. P. & Pedrosa-Soares, A.C. (2001). Brazilian Gem Provinces. The Australian Gemmologist. 21(1): 12-16. Wakita, H., Rey, P. & Schmitt, R. A. (1971). Elemental abundances of major, minor, and trace elements in Apollo 11 lunar rocks, soil and core samples. Proceedings of the Apollo 11 Lunar Science Conference, 1685-1717. ASOCIACIÓN GEOLÓGICA ARGENTINA, SERIE D, PUBLICACIÓN ESPECIAL Nº 14: 21-23 (2011) INTRODUCTION Microlite-group minerals, which are part of the pyrochlore supergroup, are mainly restricted to moderately to highly fractionated rare-element granitic pegmatites (Lumpkin & Ewing 1995). A new nomenclature scheme for the pyrochlore supergroup, approved by the CNMNC – IMA (Atencio et al. 2010), is based on the ions in the A-, B- and Y-sites. What has been referred to until now as the pyrochlore group should be referred to as the pyrochlore supergroup, and the subgroups should be changed to groups. Five groups are recommended, based on the atomic proportions of the B-atoms Nb, Ta, Sb, Ti, and W. The recommended groups are pyrochlore, microlite, roméite, betafi te, and elsmoreite, respectively. NAMES The new names are composed of two prefi xes and one root name (identical to the name of the group). The fi rst prefi x refers to the dominant anion (or cation) of the dominant valency [or H2O or ] in the Y-site. The second prefi x refers to the dominant cation of the dominant valency [or H2O or ] in the A-site. The prefi x “keno-” represents “vacancy”. When the fi rst and second prefi xes are equal, then only one prefi x is applied. Complete descriptions are missing for the majority of the microlite-group species. Only three names refer to valid mineral species on the grounds of their complete descriptions: hydroxykenomicrolite, oxystannomicrolite, and oxystibiomicrolite. Fluornatromicrolite is an IMA-approved mineral, but the complete description has not yet been published. The following fi ve names refer to minerals that need to be completely described in order to be approved as valid species: fl uorcalciomicrolite, oxycalciomicrolite, kenoplumbomicrolite, hydromicrolite, and hydrokenomicrolite. For these, there are only chemical and/or crystal structure data. Type specimens need to be defi ned. Potential candidates for several other species exist but are not characterized well enough to grant them any offi cial status. Ancient chemical data refer to wet chemical analyses and commonly represent a mixture of minerals. These data were not used here. All used data represent microprobe analyses and/or were obtained by crystal structure refinements. We also verified scarcity of crystal- chemical data in the literature. There are crystal structure determinations published for only two microlite-group minerals: hydroxykenomicrolite and kenoplumbomicrolite. The following mineral names were discarded: bariomicrolite, bismutomicrolite, plumbomicrolite, stannomicrolite, stibiomicrolite, and uranmicrolite. The new names are presented below. A table is shown indicating the combinations of dominant species of the dominant-valency group at A-site and dominant species of the dominant-valency group at Y-site for which there is evidence of a mineral. After the table, references are given for the corresponding species or potential species. The names marked with an asterisk ‘*’ refer to valid mineral species because of their complete descriptions. The other names refer to minerals that need to be completely described in order to be approved as valid species. The names of the species for which there are crystal structure determination studies are marked with a dagger ‘†’. (See table on next page) FLUORNATROMICROLITE: The IMA Proposal 98-018 for fluornatromicrolite (Witzke et al. 1998) was approved but the complete paper was never published. Some data were published by Atencio (2000). Chemical analyses that correspond to fl uornatromicrolite from other occurrences are available in the papers by Ohnenstetter & Piantone (1992), Belkasmi et al. (2000), Huang et al. (2002) and Baldwin et al. (2005). THE MICROLITE-GROUP MINERALS: NOMENCLATURE Daniel Atencio1, Marcelo B. Andrade2§ 1 Instituto de Geociências, Universidade de São Paulo, Rua do Lago, 562, 05508-080,São Paulo, SP, Brazil, § datencio@usp.br 2 Instituto de Física de São Carlos, Universidade de São Paulo, 13560-970, São Carlos, SP, Brazil Key words: nomenclature, pyrochlore supergroup, microlite group. 22 THE MICROLITE-GROUP MINERALS: NOMENCLATURE FLUORCALCIOMICROLITE: There are several analyses of fl uorcalciomicrolite in the literature, e.g., Lumpkin et al. (1986), Baldwin (1989), Ohnenstetter & Piantone (1992), Tindle & Breaks (1998), Huang et al. (2002), Geisler et al. (2004), Tindle et al. (2005). OXYCALCIOMICROLITE: Černý et al. (2004) [stibiomicrolite]; Guastoni et al. (2008) [microlite]. OXYSTANNOMICROLITE: Vorma & Siivola (1967) [sukulaite]; Ercit et al. (1987) [stannomicrolite]. The type specimen of “sukulaite” described by Vorma & Siivola (1967) should be considered as the type for oxystannomicrolite. KENOPLUMBOMICROLITE: Bindi et al. (2006): crystal structure study of kenoplumbomicrolite. OXYSTIBIOMICROLITE: Groat et al. (1987): Type sample for “stibiomicrolite”; Novák & Černý (1998). The type specimen of “stibiomicrolite” described by Groat et al. (1987) should be considered as the type for oxystibiomicrolite. HYDROKENOMICROLITE: Andrade & Atencio (unpublished data) HYDROMICROLITE: Andrade & Atencio (unpublished data) HYDROXYKENOMICROLITE: Ercit et al. (1993): crystal structure study of “cesstibtantite”. The type specimen of “cesstibtantite” described by Voloshin et al. (1981) should be considered as the type for hydroxykenomicrolite. FORMULAE Formulae are given for the species for which we have analytical evidence. Note that subordinate components on the A-, B-, X- or Y-sites have no nomenclatural significance. We show specific examples here that are typical of the minor components observed, but any of these could be replaced by “#”, indicating an unspecifi ed heterovalent species required for charge balance. oxystannomicrolite* Sn2Ta2O6O oxystibiomicrolite* (Sb3+,Ca)2Ta2O6O hydroxykenomicrolite*† (, Na,Sb3+)2Ta2O6(OH) fl uornatromicrolite (Na,Ca,Bi)2Ta2O6F fl uorcalciomicrolite (Ca,Na)2Ta2O6F oxycalciomicrolite Ca2Ta2O6O kenoplumbomicrolite (Pb,)2Ta2O6(,O,OH) hydromicrolite (H2O,)2Ta2(O,OH)6(H2O) hydrokenomicrolite (,H2O)2Ta2(O,OH)6(H2O) ACKNOWLEDGEMENTS We acknowledge FAPESP (Fundação de Amparo à Pesquisa do Estado de São Paulo) for financial support (processes 2008/04984-7 and 2009/09125-5). REFERENCES Atencio, D. (2000). Type Mineralogy of Brazil. 1st. ed. São Paulo: Museu de Geociências - USP. 114p. Dominant species of the dominant-valency group at Y-site OH F O H2O  Na fl uornatromicrolite Ca fl uorcalciomicrolite oxycalciomicrolite Sn2+ oxystannomicrolite* Sr Pb2+ kenoplumbomicrolite† Sb3+ oxystibiomicrolite* Y U4+ H2O hydromicrolite  hydroxykenomicrolite*† hydrokenomicrolite Dominant species of the dominant- valency group at A-site 23ASOCIACIÓN GEOLÓGICA ARGENTINA, SERIE D, PUBLICACIÓN ESPECIAL Nº 14 (2011) Atencio, D., Andrade, M.B., Christy, A.G., Gieré, R. & Kartashov, P.M. (2010). The pyrochlore supergroup of minerals: nomenclature. Can. Mineral. 48: 673-698. Baldwin, J.R. (1989). Replacement phenomena in tantalum minerals from rare-metal pegmatites in South Africa and Namibia. Mineral. Mag. 53: 571-581. Baldwin, J.R., Hill, P.G., Finch, A.A., von Knorring, O. & Oliver, G.J.H. (2005). Microlite-manganotantalite exsolution lamellae: evidence from rare-metal pegmatite, Karibib, Namíbia. Mineral. Mag. 69: 917-935. Belkasmi, M., Cuney, M., Pollard, P.J. & Bastoul, A. (2000). Chemistry of the Ta-Nb-Sn-W oxide minerals from the Yichun rare metal granite (SE China): genetic implications and comparison with Moroccan and French Hercynian examples. Mineral. Mag. 64: 507–523 Bindi, L., Zoppi, M. & Bonazzi, P. (2006). Plumbomicrolite from the Ploskaya Mountain, Keivy Massif, Kola Peninsula, Russia: composition and crystal structure. Periodico di Mineralogia 75: 51-58. Černý, P., Chapman, R., Ferreira, K. & Smeds, S-A. (2004). Geochemistry of oxide minerals of Nb, Ta, Sn, and Sb in the Varuträsk granitic pegmatite, Sweden: The case of an “anomalous” columbite- tantalite trend. Am. Mineral. 89: 505–518. Ercit, T.S., Černý, P. & Siivola, J. (1987) The composition of stannomicrolite. N. Jb. Miner., Monat. 249- 252. Ercit, T.S., Černý, P. & Hawthorne, F.C. (1993) Cesstibtantite—a geologic introduction to the inverse pyrochlores. Mineralogy and Petrology, 48: 235-255. Geisler, T., Berndt, J., Meyer, H.-W., Pollok, K. & Putnis, A. (2004) Low-temperature aqueous alteration of crystalline pyrochlore: correspondence between nature and experiment. Mineral. Mag. 68: 905–922. Groat, L.A., Černý, P. & Ercit, T.S. (1987) Reinstatement of stibiomicrolite as a valid species. Geoliska Föreningens i Stockholm Förhandlingar 109: 105-109. Guastoni, A., Diela, V. & Pezzotta, F. (2008) Vigezzite and associated oxides of Nb–Ta from emerald- bearing pegmatites of the Vigezzo Valley, Western Alps, Italy. Can. Mineral. 46: 619-633. Huang, Xiao Long, Wang, Ru Cheng, Chen, Xiao Ming, Hu, Huan & Liu, Chang Shi (2002) Vertical variations in the mineralogy of the Yichun topaz–lepidolite granite, Jiangxi Province, Southern China. Can. Mineral. 40: 1047-1068. Lumpkin, G.R. & Ewing, R.C. (1995). Geochemical alteration of pyrochlore group minerals: Pyrochlore subgroup. Am. Mineral. 80: 732-743. Lumpkin, G.R., Chakoumakos, B.C. & Ewing, R.C. (1986). Mineralogy and radiation effects of microlite from the Harding pegmatite, Taos County, New Mexico. Am. Mineral. 71: 569-588. Novák, M. & Černý, P. (1998). Niobium-tantalum oxide minerals from complex granitic pegmatites in the Moldanubicum, Czech Republic: primary versus secondary compositional trends. Can. Mineral. 36: 659-672. Ohnenstetter, D. & Piantone, P. (1992). Pyrochlore- group minerals in the Beauvoir peraluminous leucogranite, Massif Central. France. Can. Mineral. 30: 771-784. Tindle, A.G. & Breaks, F.W. (1998). Oxide minerals of the Separation Rapids rare-element granitic pegmatite group, Northwestern Ontario. Can. Mineral. 36: 609-635. Tindle, A.G., Selway, J.B. & Breaks, F.W. (2005) Liddicoatite and associated species from the McCombe spodumene-subtype rare-element granitic pegmatite, Northwestern Ontario, Canada. Can. Mineral. 43: 769-793. Voloshin, A.V., Men’shikov, Yu.P., Pakhomovskiy, Ya.A. & Polezhaeva, L.I. (1981) Cesstibtantite, (Cs,Na)SbTa4O12 a new mineral from granitic pegmatites. Zapiski Vsesoyuznoye Mineralogichestogo Obshchestvo 116: 345-351 (in Russian). Vorma, A. & Siivola, J. (1967) Sukulaite Ta2Sn2O7 and wodginite as inclusions in cassiterite in the granite pegmatite in Sukula, Tammela, in SW Finland. Bulletin de la Commission géologique de Finlande, 229, 173-187. Witzke, T., Steins, M. Doring, T., Schuckmann, W., Wegner, R. & Pollmann, H. (1998) Fluornatromicrolite. IMA CNMMN Submission 98-018. ASOCIACIÓN GEOLÓGICA ARGENTINA, SERIE D, PUBLICACIÓN ESPECIAL Nº 14: 25-27 (2011) INTRODUCTION One of the most important pegmatite provinces in the world, the Eastern Brazilian Pegmatite Province (EBPP), occurs in Brazil. This province is located at the East side of the Saõ Francisco craton, mainly in the state of Minas Gerais. Among these pegmatites, the Sapucaia pegmatite was selected for detailed sampling. This pegmatite was probably discovered around 1920-1930 and was initially exploited for beryl and muscovite (Pecora et al. 1950, Cassedanne & Baptista 1999). Sapucaia pegmatite is especially famous for its complex phosphate mineral associations, among which six new phosphate mineral species were first described: frondelite, faheyite, moraesite, barbosalite, tavorite, and lipscombite (Atencio 2000). The discovery of these new mineral species leads to a good knowledge of the Sapucaia mineralogy; however, only a brief description of the pegmatite body exists. The aims of this work are (i) to describe the variations of the mineral assemblages corresponding to the different zones of the pegmatites, (ii) to investigate in detail the petrographic relations among phosphates as well as their chemical compositions in order to better understand the transformation sequences which affected these minerals, and (iii) to shed some light on the genesis of the Sapucaia pegmatite throughout the geochemical evolution of the phosphate minerals and their associated silicates. GEOLOGICAL SETTING AND DESCRIPTION OF THE PEGMATITE BODY GEOLOGICAL SETTING The Eastern Brazilian Pegmatite Province (EBPP) is divided into several districts, among which the Conselheiro Pena district (Pedrosa-Soares et al. 2009) in which the Sapucaia pegmatite occurs. During the Brazilian orogeny (700-450 Ma), several pre-, syn-, and post-tectonic granitoids took place in the EBPP (Bilal et al. 2000), originating most of the pegmatites (Bilal et al. 2000; Morteani et al. 2000). Two of these intrusions crosscut the cover and the basement rocks of the Conselheiro Pena district: the Galiléia and Urucum magmatic suites which belong to the G1 and G2 supersuites, respectively (Pedrosa-Soares et al. 2001). The Galiléia granitoid (595 Ma) is a metaluminous suite characterized by a polydiapiric batholith consisting mainly of granodiorites and tonalites with minor granites. These rocks are associated with the precollisional magmatism of the Brazilian orogeny and have calcalkaline affi nities (Nalini et al. 2000; Pedrosa-Soares et al. 2001). The Urucum suite (582 Ma) is composed by four different types of rocks: a feldspar megacrystal-bearing granite (Urucum facies), a medium to