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Anoxic oceanic cond...
Anoxic oceanic conditions during the late Permian mass extinction-evidence from the Chutani formation, Bolivia
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- Nina, Lidia (författare)
- Luleå tekniska universitet,Geovetenskap och miljöteknik,Institute of Geological Research and Environment, Geological Sciences Faculty, Mayor San Andres University, 14500, La Paz, Bolivia
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- Paula-Santos, G.M. (författare)
- Institute of Geosciences, University of Campinas, Rua Carlos Gomes, 250, Campinas, Brazil
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- Sial, A.N. (författare)
- NEG-LABISE, Dept. of Geology, Federal University of Pernambuco, Recife, PE, Brazil
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- Bark, Glenn (författare)
- Luleå tekniska universitet,Geovetenskap och miljöteknik
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- Wanhainen, Christina (författare)
- Luleå tekniska universitet,Geovetenskap och miljöteknik
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- Jiménez, G. (författare)
- Yacimientos Petrolíferos Fiscales Bolivianos, Bolivia
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- Blanco, M. (författare)
- Institute of Geological Research and Environment, Geological Sciences Faculty, Mayor San Andres University, 14500, La Paz, Bolivia
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(creator_code:org_t)
- Elsevier, 2020
- 2020
- Engelska.
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Ingår i: Journal of South American Earth Sciences. - : Elsevier. - 0895-9811 .- 1873-0647. ; 103
- Relaterad länk:
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https://urn.kb.se/re...
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https://doi.org/10.1...
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Abstract
Ämnesord
Stäng
- We analyze diagenesis of carbonate rocks from the Late Permian Chutani Formation of western Bolivia (San Pablo de Tiquina section) in the southern Lake Titicaca zone, which is a sedimentary succession of semiarid tidal flat comprised of mixed carbonate and siliciclastic units. The diagenetic study includes petrographic analysis (conventional petrography and cathodoluminescence) and geochemical analysis (carbon and oxygen isotopes and minor element chemistry). An integrated study of lithofacies and isotope stratigraphy of carbonates shows a succession of five types of depositional environments: tidal barrier, tidal flat, shoal coastal and shoreface. The Chutani Formation was subjected to different diagenetic processes including micritization, cementation, mechanical compaction, dissolution, neomorphism, dolomitization and dedolomitization that occurred during marine to shallow burial stages. Carbon isotope (δ13C) values range between −7 and 2.9‰ (VPDB) with variations linked to stratigraphic changes. The transgressive stage of the basin exhibits an upwards decreasing trend of δ13C values whereas regression is marked by an increase in such values. The oxygen isotope values (δ18O) vary from −16.6 to −1‰ VPDB with lighter values towards the top of the stratigraphy. The transgressive trend may reflect mixing of meteoric water and/or volcanic-hydrothermal fluids with seawater or progressive oxygenation with enhanced circulation conditions. Heavier values during regression may reflect more evaporitic and anoxic conditions towards the Permian-Triassic boundary. Significant variation in isotope values among neighbouring samples is observed, especially during trangression, which may be the result of different diagenetic processes.
Ämnesord
- NATURVETENSKAP -- Geovetenskap och miljövetenskap -- Geologi (hsv//swe)
- NATURAL SCIENCES -- Earth and Related Environmental Sciences -- Geology (hsv//eng)
Nyckelord
- Carbon isotopes
- Oxygen isotopes
- Permian-triassic boundary
- mass extinction
- Ore Geology
- Malmgeologi
Publikations- och innehållstyp
- ref (ämneskategori)
- art (ämneskategori)
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