Catastrophic environmental transition at the Permian-Triassic Neo-Tethyan margin of Gondwanaland: Geochemical,isotopic and sedimentological evidence in the Spiti Valley,India |
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| Affiliation: | 1. Department of Earth & Environmental Sciences, 227 Hutchison Hall, University of Rochester, Rochester, NY 14627, USA;2. INSA Honorary Scientist, 103, Sector 7, Panchkula, Haryana 134109, India;3. Department of Geology, Banaras Hindu University, Varanasi, UP 221005, India;4. Department of Geology, Panjab University, Sector-14, Chandigarh-160014, India;1. Institute of Petrology and Structural Geology, Charles University, Albertov 6, 14328 Prague, Czech Republic;2. Department of Materials Science and Physics, University of Salzburg, Hellbrunnerstraße 34, A-5020 Salzburg, Austria;3. Centre of Isotopic Research, VSEGEI, 74 Sredny prospect, 199106 St. Petersburg, Russia;4. Department of Geological Sciences, Masaryk University, Kotlářská 267/2, Brno, Czech Republic;5. Geological Institute, Slovak Academy of Sciences, Dúbravská cesta 9, Bratislava, Slovak Republic;1. Birbal Sahni Institute of Palaeosciences, 53, University road Lucknow 226007, India;2. Department of Geology, University of Jammu, Jammu 180006, India;3. Directeorate of Geology and Minning, Jammu and Kashmir Government, Srinagar, India;1. State Key Laboratory of Biogeology and Environmental Geology, China University of Geosciences, Wuhan 430074, China;2. Department of Earth and Atmospheric Sciences, University of Alberta, Edmonton T6G 2E3, Canada;1. Plymouth University, School of Geography, Earth and Environmental Sciences, Drake Circus, Plymouth, Devon PL4 8AA, UK;2. Natural History Museum, Department of Earth Sciences, Cromwell Road, London SW7 5BD, UK;3. Department of Geology, University of Georgia, Athens, GA 30602-2501, USA;4. Department of Earth Science, University of Northern Iowa, Cedar Falls, IA 50614, USA;5. MTA-ELTE Geological, Geophysical and Space Science Research Group, Pázmány s. 1/c, 1117 Budapest, Hungary |
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| Abstract: | Interpreting global consequences of the Permian-Triassic (P-Tr) extinction requires examination across paleogeographic realms of Pangaea. The Spiti Valley in India, remnant of the peri-Gondwanan shelf, preserved trails of this environmental catastrophe in the Neo-Tethys Ocean. We document new sedimentological observations and high-resolution trace element concentrations and carbon, oxygen, lead isotope data across the P-Tr boundary in Spiti. Framboidal pyrites, fossils and laminated lithology of the Late Permian shales indicate deeper anoxic depositional environment while δ13Corg excursions of 2.4‰ and 3.1‰ in Atargu and Guling outcrops, respectively, identify the P-Tr transition across a clayey, partly gypsiferous ferruginous layer. Sedimentological similarities of this layer to other Neo-Tethyan sections from Transcaucasia and Iran indicate subaqueous oxidation of shallow marine sediments on a regional scale. Light Rare Earth Element – enriched Late Permian shales with conspicuous Ce–Eu anomalies reflect their source from the adjacent Panjal Trap basalts (ca. 289 Ma) of Kashmir. Continental crustal Nb–Ta and Zr–Hf anomalies appear at the P-Tr boundary sediments, and prevail through the overlying Early Triassic carbonates. Original Pb isotope ratios, along with an increasing Pb abundance closer to the P-Tr boundary, distinguish the volcanic source of the Late Permian shales from the continental crustal siliciclastic signature of the Early Triassic carbonates. Our δ13Corg, trace element and Pb isotope record from Spiti indicate catastrophic changes in sediment sources and facies, with effects on carbon cycle and are consistent with an abrupt episode of marine regression and erosional forcing, also observed elsewhere along northern Gondwanaland. Simultaneous eruption of Siberian volcanics and bolide impacts in Parana basin of Brazil and elsewhere implicating impact-triggered volcanism, left catastrophic regional-global imprints on sea level, climate, marine anoxia and tectonic stability that connected the P-Tr crisis across terrestrial and marine realms worlwide. |
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