عنوان

Evidence of Catastrophe in the Permian - Triassic Tethyan Ocean

Number

TL48237

.Language of Text, Soundtrack etc

انگلیسی

Title Proper

Evidence of Catastrophe in the Permian - Triassic Tethyan Ocean

General Material Designation

[Thesis]

First Statement of Responsibility

Nilotpal Ghosh

Subsequent Statement of Responsibility

Basu, Asish R.; Garzione, Carmala

Name of Publisher, Distributor, etc.

University of Rochester

Date of Publication, Distribution, etc.

2015

Specific Material Designation and Extent of Item

144

Text of Note

Committee members: Garzione, Carmala; Kessler, John; Perucchio, Renato; Schroder, Wolf U.

Text of Note

Place of publication: United States, Ann Arbor; ISBN=978-1-321-74955-7

Dissertation or thesis details and type of degree

Ph.D.

Discipline of degree

School of Arts and Sciences

Body granting the degree

University of Rochester

Text preceding or following the note

2015

Text of Note

Interpreting global consequences of the Permian-Triassic (P-Tr) extinction event at ∼252 million years (Ma) before present requires geological examination across paleogeographic sites of Pangaea, including Panthalassic Ocean, Paleotethys, Neotethys, Laurasia and Gondwanaland. Despite numerous studies on Tethyan and Boreal sediments extending from China and Europe to Canada, Neo-Tethyan sediments spanning this geological boundary have received much lesser attention. This thesis provides a detailed geological, geochemical and isotopic characterization of the P-Tr boundary in Spiti Valley of India that is a remnant of the peri -Gondwana continental shelf along Neo-Tethys Ocean. New sedimentological observations and high-resolution trace element and carbon, oxygen, lead isotope data across the P-Tr boundary in Spiti are reported and documented for the first time. Discovery of framboidal pyrites, fossil assemblages and laminated lithology of the Late Permian shales indicate deeper anoxic depositional environment while carbon isotope excursions 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 Ce - Eu anomalies reflect their source as Panjal Trap basalt (ca. 289 Ma) of Kashmir while Nb-Ta and Zr-Hf anomalies at and above the P-Tr boundary indicate increased erosion in oxidizing conditions. The δ¹³C _org, trace element and Pb isotope record from Spiti indicate catastrophic changes in sediment sources and facies, with effects on global carbon cycle and are consistent with an abrupt episode of marine regression and erosional forcing, also observed elsewhere along northern Gondwanaland. In contrast, the Raman spectroscopic and lead isotope investigation of a P-Tr boundary Tethyan section in Vietnam shows large scale deposition of black carbon soot into the Paleo-Tethys, a likely cause of marine anoxia. We propose that a chain of catastrophic processes, primarily triggered by Siberian flood volcanic eruption and bolide impact in the Parana basin of Brazil and possibly elsewhere, in combination, left catastrophic local to regional imprints on sea level, climate, marine anoxia and tectonic instability that connected the P-Tr crisis across the terrestrial and marine realms of Pangaea.

Geology; Geochemistry

Subject Term

Earth sciences;Carbon isotope;Gondwana;Lead isotope;Neo-tethys;Permian-triassic;Trace elements

Sheikh, Faraz M.

Basu, Asish R.; Garzione, Carmala

Subdivision

School of Arts and Sciences

University of Rochester

Call Number

1688679939; 3703224

Electronic name

p

[Thesis]

276903

a

Y