Browsing by Author "Playà, E"

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    Evaporites with inherited marine and continental signatures: the Gulf of Carpentaria, Australia, at ~70 ka
    (Elsevier B. V., 2007-07-12) Cendón, DI; Playà, E; Chivas, AR; Trave, A; Wyndham, T; Garcia, A; Hankin, SI
    Changes in sea-level and associated climatic fluctuations resulted in extreme and cyclic changes in depositional environments in the Gulf of Carpentaria region (N, Australia). Disconnection from the sea led to the establishment of “Lake Carpentaria”. In this environment, evaporitic conditions at ~70 ka produced an alternation of μm to mm-thick evaporitic and micritic laminae. These precipitates are primary features, deposited in a shallow lake. Elemental and isotope geochemistry of gypsum and micrite laminae show a complex evaporitic environment where initially marine waters evaporated with the input of continental waters compensating for evaporative losses. Reduced continental input could not support a lake of the initial dimensions and the lake retracted to the deepest part of the basin along the north-eastern side. In a lake with smaller water volume, continental solutes became dominant. The strontium contents of gypsum range from 691 to 1353 ppm, gypsum-δ34S values from +21.8 to +22.5%, gypsum-δ18O values from +14.1 to +16.5% and 87Sr/86Sr from 0.7093 to 0.7098. While Sr contents and sulfur isotopes indicate marine contributions, strontium isotopes and oxygen isotopes in sulfates reveal continental inputs and processes such as recycling of evaporites, sulfate reduction and potential reservoir effects. Carbonate-δ13C and δ18O values in micrite also reveal a continental influence and perhaps variations in organic matter signatures associated with climatic and vegetation changes. In order to assess the provenance of continental waters reaching Lake Carpentaria at this time, REE elements in evaporitic gypsum were analysed and compared to results from modern rivers in the area. The REE-normalized patterns in gypsum samples are like those found in northern Cape York rivers (and unlike seawater), restricting the potential continental inputs into the evaporatic basin to a limited geographical area. The thickness of the calcite-gypsum couplets is consistent with those precipitated annually in modern evaporitic environments. This and the marked fluctuation between dry (gypsum laminae) and wet (micritic layer) suggests a reduced monsoon-like rainfall pattern operating in northern Australia during evaporite precipitation. © 2007 Elsevier
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    The Gulf of Carpentaria, Australia, at ~70 ka: Isotopic, trace and REE constraints
    (Centre for Groundwater Studies, 2006-12-13) Cendón, DI; Playà, E; Chivas, AR; Trave, A; Wyndham, T; Garcia, A; Hankin, SI
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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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    Non-marine evaporites with both inherited marine and continental signatures: the Gulf of Carpentaria, Australia, at similar ~ 70 ka
    (Elsevier, 2007-10-15) Playà, E; Cendón, DI; Trave, A; Chivas, AR; García, A
    Changes in sea-level and associated climatic fluctuations resulted in extreme and cyclic changes in depositional environments in the Gulf of Carpentaria region (N. Australia). Disconnection from the sea led to the establishment of a "Lake Carpentaria", perched above sea-level. In this environment, evaporitic conditions at about 70 ka produced a repetitive alternation of Pm to mm-thick evaporitic and micritic laminae with a varve-like appearance. These precipitates are interpreted as primary features, deposited in a shallow lake that retained limited water in its centre (core MD-32). Elemental and isotope geochemistry of gypsum and micrite laminae show a complex evaporitic environment where initially marine waters evaporated with the input of continental waters compensating for evaporative losses. Reduced continental input could not support a lake of the initial dimensions and the lake contracted to the deepest part of the basin along the north-eastern side of the basin. In a lake with smaller water volume, continental solutes became apparent. While Sr contents and sulfur isotopes indicate marine contributions, strontium isotopes and oxygen isotopes in sulfates reveal continental inputs and other processes such as recycling of previously precipitated evaporites, sulfate reduction and potential reservoir effects. Carbonate- delta C-13 and delta O-18 values in micritic levels also reveal a continental influence and perhaps variations in organic matter signatures associated with climatic variations and vegetation changes. The REE-normalized patterns in gypsum samples are like those found in northern Cape York rivers, restricting the potential continental inputs into the evaporatic basin to a limited geographical area. The small depletion in LREE-normalized patterns between gypsum and river samples is interpreted as a marine influence while depletions in HREE are considered to be the result of fractionation of HREE during gypsum crystallization. © 2007, Elsevier Ltd.
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    Using multiple geochemical proxies to trace origin of gypsum (Gulf of Carpentaria, Australia, -70ka)
    (Sociedad Geologica de Espana, 2007-05) Playà, E; Cendón, DI; Trave, A; Chivas, AR; García, A
    This paper discusses the geochemical signature of the Carpentaria evaporitic levels using minor-trace and rare-earth elements (REE) and Sr, O, C and S isotopes. The chemistry of these evaporites reveals important criteria for distinguishing between ancient marine and non-marine evaporites. © 2007 Sociedad Geologica de Espana