Terrestrial Records of Carbon Cycle Perturbations in the Triassic and Jurassic

Abstract

The emplacement of Large Igneous Province (LIPs) through geologic time has resulted in kill mechanisms such as greenhouse gas destabilization and ocean acidification leading to mass extinction in all spheres of Earth. The Triassic and Early Jurassic period is characterized by the Central Atlantic Magmatic Province (CAMP) and Karoo and Ferrar LIP, respectively. Its corollary event has been widely studied in the marine environment, with minimal studies focusing on the terrestrial realm. With the establishment of synchroneity between the Earth's carbon cycling in Earth history and its isotopic signature preserved in the sedimentary archive, I employed the Terrestrial sedimentary record from South Africa (Elliot Formation, Karoo basin) using the carbon isotope and biological markers to reconstruct the earth carbon cycle. The studied section at Barkly Pass has a maximum depositional age of 201 ± 0.08Ma and suggests preserving the T-J boundary with a negative excursion of ~-5. Similarly, the terrestrial sedimentary record of Kayenta Formation, Gold Spring, Arizona, is used to unravel the Early Jurassic carbon cycling (Pleinsbachian – Toarcian (Pl - To) Boundary and Toarcian Carbon Isotope Excursion (T-CIE)) using the carbon and oxygen isotope signature preserved within the sedimentary archive. In addition, the research extends to understanding the local climate response to the emplacement of Karoo LIP in the Early Jurassic (~183Ma) using the volcanic soil forming at the flank volcanic complex. Overall, this study shows that the Triassic and Jurassic Periods are marked with a relatively light organic carbon isotope as low as -30‰ in the terrestrial environment and contributed to the sizeable growing dataset from other environmental settings for the studied geologic record.

Date of Award	Aug 2023
Original language	American English
Supervisor	Aisha Alsuwaidi (Supervisor)