Browsing by Author "Rosell, L"

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    Large celestine orebodies formed by early-diagenetic replacement of gypsified stromatolites (Upper Miocene, Montevive–Escúzar deposit, Granada Basin, Spain)
    (Elsevier, 2015-01-01) García-Veigas, J; Rosell, L; Cendón, DI; Gilbert, L; Martín, JM; Torres-Ruiz, J; Ortí, F
    The Montevive and the Escúzar stratabound celestine orebodies in the Upper Miocene evaporite succession of the intramontane Granada Basin (Spain) constitute one of the largest strontium deposits in the world. Celestine occurs within a gypsum/anhydrite–halite evaporite sequence where it replaces gypsum and gypsified stromatolites preserving carbonate peloids. 87Sr/86Sr and δ34S values in the Montevive celestine deposit are close to those reported for the saline unit (Chimeneas Halite; marine to nonmarine) but higher than those of the overlying gypsum unit (Agrón Gypsum; nonmarine). 87Sr/86Sr and δ34S isotope values in the Escúzar celestine deposit match the nonmarine values recorded in the upper part of the Agrón Gypsum. The similarity in isotope values between celestine and the corresponding gypsum host in the Escúzar deposit points to early-diagenetic mineralization. According to that, both orebodies are diachronous. Gypsum pseudomorphs and molds, intraformational breccias and karst structures in these celestine deposits point to dissolved gypsum as the main sulfate source. Diagenetic–hydrothermal CaCl2 brines are interpreted to be the main strontium source. The spatial relationship between gypsified stromatolites and the ore deposits suggests the existence of coeval thermal springs related to fractures, bordering the saline lake. The proposed model envisages gypsum dissolution by SO42 −-poor and Sr2 +-rich, CaCl2 diagenetic–hydrothermal water discharging in coastal ponds at times of dry periods and low meteoric water inflow. The increase in SO42 − concentration by gypsum dissolution and the low solubility of SrSO4 would lead to celestine precipitation replacing gypsum and gypsified stromatolites. © 2014 Elsevier B.V.
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    Marine to lacustrine evolution in an evaporitic environment: the late miocene Lorca Basin, Spain
    (U.S. Department of the Interior and U.S. Geological Survey, 2015-06-15) García-Veigas, J; Cendón, DI; Gilbert, L; Rosell, L; Ortí, F; Playà, E; Prats, E; Soria, JM; Corbí, H; Sanz, E
    The Lorca Basin, in the eastern sector of the Betic Range (SE Spain), is an intramontane basin recording an evaporitic succession (La Serrata Formation), of up to 300 m thick, with a ~ 235 m thick saline unit within. Altogether, the evaporitic record was originally interpreted as Messinian (Geel, 1976) and later assigned to Tortonian (Krijgsman and others, 2000). The detailed geochemical study provides relevant paleogeographic information at local scale and highlights the importance of hydrochemical changes taking place in coastal evaporite basins changing between marine and non-marine conditions without lithological variations. A stratigraphic framework is proposed correlating the outcropping gypsum beds (Gypsum Mb of La Serrata Fm) and the subsurface saline succession (Halite Mb) by means of strontium and sulfate isotopes (fig. 1). In the lower part of the Gypsum Mb the isotopic trends suggest that gypsum formed from marine waters while in the upper part, with Triassic isotopic signals, gypsum formed in a coastal lake mainly fed by non-marine waters. In the Halite Mb, the textures indicate precipitation in a very shallow, often dried, environment. Fluid inclusion compositions and bromine contents in salt show an evolution from normal marine brines, to brines resulting from the recycling of previously precipitated halite essentially by means of non-marine waters in a coastal lake setting. The overlying Laminated Pelite Mb (Geel, 1976) consists in its lower part of a number of non-marine gypsum beds intercalated between marine marls suggesting post-evaporitic refilling events of the Lorca Basin by the Mediterranean Sea before its final continentalization during the Pliocene. Biostratigraphic studies in progress are expected to refine age allocation within the evaporitic unit and therefore improve our understanding of the relationship to the “Messinian Salinity Crisis”. © 2015 The Authors
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    Salt deposition and brine evolution in the Granada Basin (Late Tortonian, SE Spain)
    (Elsevier Science BV, 2013-01-01) García-Veigas, J; Cendón, DI; Rosell, L; Orti, F; Torres Ruiz, J; Martín, JM; Sanz, E
    A group of sedimentary basins in the Betic Chain were formed during the Middle-Late Miocene as a result of the closure of the Tethys during the Alpine orogeny. In the Late Miocene (Tortonian-Messinian) the connections between the Atlantic Ocean and Mediterranean Sea were interrupted and those basins hosted major evaporites. The Granada Basin, an 'inner basin' located far from the Mediterranean, contains a thick rock salt deposited during the latest Tortonian in the transition from marine to non-marine conditions. In the centre of the basin, three halite-bearing units overlie a basal anhydrite bed: the Lower Halite Unit, the Intermediate Sandstone Unit and the Upper Halite Unit. Fluid inclusion compositions and bromine concentrations in halite, together with stable isotopes (delta S-34(sulfate), delta O-18(sulfate) and Sr-87/Sr-86) indicate a mixture of different inflow waters in the Granada Basin, beginning with a marine lagoon that evolved into a salt-pan strongly isolated from the sea. Saline waters evolved from sulfate-rich marine-derived to sulfate-depleted non-marine brines influenced by the addition of CaCl2-rich inputs. These CaCl2-rich waters were probably linked to thermal fluids associated with a major crustal fracture system (Crevillente or Cadiz-Alicante fault system) that cuts through the Granada Basin. © 2013, Elsevier Ltd.
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    Sulfate isotope compositions (δ34S, δ18O) and strontium isotopic ratios (87Sr/86Sr) of Triassic evaporites in the Betic Cordillera (SE Spain)
    (SGE, 2014-01-01) Ortí, F; Pérez-López, A; García-Veigas, J; Rosell, L; Cendón, DI; Pérez-Valera, F
    Sulfate isotope compositions (δ34S and δ18O) and strontium isotope ratios (87Sr/86Sr) of Triassic evaporites in the Betic Cordillera are addressed for the first time in the present work. Isotope values have been determined in gypsum and anhydrite samples of the Germanic-type facies (Buntsandstein, Muschelkalk and Keuper) coming from different outcrops spanning the complete Triassic Period and corresponding to both the Internal Zones and the External (Prebetic, Subbetic) Zones of this chain. More precise age assignments and stratigraphic controls are often obscured because of the intense halokinetic and tectonic deformation occurred during the Alpine Orogeny in the Betic Cordillera. Isotope values of Triassic sulfates obtained in the present study range between 12.5 and 16.6 ‰ for δ34S, between 8.9 and 16.9 ‰ for δ18O, and between 0.707615 and 0.708114 for 87Sr/86Sr. These values, as a whole, are in agreement with those of worldwide Triassic marine evaporites.