Organic Carbon Isotope Stratigraphy in the Kuqa River Section, Tarim Basin, and the Corresponding Triassic-Jurassic Boundary.

The boundary between the Triassic and Jurassic periods is a key moment in Earth history, which is distinguished by one of the five biggest mass extinctions, Pangea progressively breaking apart with the opening of the central Atlantic Ocean, eruption of Central Atlantic Magma Province, and a dramatic increase in the CO2 concentration. However, the major occurrence of terrestrial sediments in China has been difficult to bio-stratigraphically correlate with the Global Stratotype Section and Point (GSSP) defined in marine strata from the Triassic-Jurassic boundary (TJB). Two new <5I3C wood stratigraphic curves in the Kuqa River section were generated from two independent samplings, focusing on the materials within the charcoal and coalified fossil wood and representing the synchronous evolution of <5I3C in atmospheric CO2. The consistency of the two results proves the repeatability of this study, verifying the method of carbon-isotope stratigraphic sampling. The terrestrial Kuqa River section in the Tarim Basin is well correlated with the TJB of GSSP in Austria and other typical global sections, as constrained by the biostratigraphy of sporo-pollen assemblages and mega-plant fossils. The end-Triassic mass extinction (ETE) beginning horizon and synchronous TJB of GSSP are located near the bottom of Beds 38 and 41, respectively. The obvious negative carbon isotope excursion took place at the of the ETE beginning horizon and TJB. The significant fluctuations of carbon-isotope records in both marine and terrestrial strata across the ETE and TJB have been discovered globally, suggesting a global perturbation of carbon reservoirs within Earth surface cycles during this period. [ABSTRACT FROM AUTHOR]