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Quaternary exhumation history of the NE Tibetan Plateau revealed by peculiar distributions of polycyclic aromatic hydrocarbons in core extracts from the Sanhu depression, eastern Qaidam basin
Author(s) -
Yin Mengsha,
Huang Haiping
Publication year - 2020
Publication title -
journal of quaternary science
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.142
H-Index - 94
eISSN - 1099-1417
pISSN - 0267-8179
DOI - 10.1002/jqs.3235
Subject(s) - geology , provenance , quaternary , plateau (mathematics) , source rock , sedimentary rock , structural basin , paleontology , maturity (psychological) , organic matter , facies , geochemistry , psychology , mathematical analysis , developmental psychology , chemistry , mathematics , organic chemistry
Reworked organic matter (ROM) has been frequently encountered in fresh organic matter (FOM) in young sedimentary basins. Our study reports an ROM‐dominated sequence from 21 borehole cores of the Late Pliocene–Quaternary strata in the Sanhu depression of the eastern Qaidam basin in northwestern China. Reworked organic matter occurrence is confirmed by Rock‐Eval pyrolysis results, high Ro values, and reversed polyaromatic hydrocarbon (PAH) maturity trends showing elevated maturities. Rock–source correlation using molecular fingerprints of biomarkers shows ROM was derived from Jurassic freshwater lacustrine source rocks dominated by terrestrial input, contrasting the immature Quaternary FOM developed in anoxic, saline lacustrine facies. The ROM provenance is traced northward to the southern Qilian Mountains. Maximum burial depths of ROM prior to erosion have been inferred by a burial depth–Rc (calculated vitrinite reflectance) correlation. Two chronological boundaries (1.83 Ma and 3.12 Ma) displaying distinct biomarker fingerprints are obtained from a previously reported chronological framework in the study area. Accordingly, an eroded thickness of 1214 m and an average erosion rate of 94 cm/ka of the ROM provenance areas during this temporal interval are derived. Our study has illustrated the potential value of geochemical compositions of ROM with constrained provenances in investigating the exhumation history of a mountain.