Decoupled δ13Ccarb and δ13Corg records at Triassic–Jurassic boundary interval in eastern Tethys: Environmental implications for spatially different global response

• Published in: Geoscience Frontiers
• Main Author: Yuzhu Ge
• Format: Article in Journal/Newspaper
• Language: English
• Published: Elsevier 2021
• Subjects: Triassic–Jurassic; δ13C records; Eastern Tethys; Global difference; Geology; QE1-996.5; Ocean acidification
• Online Access: https://doi.org/10.1016/j.gsf.2021.101146; https://doaj.org/article/85ff9654ea7e495492d8e715994c2b93

Although δ13C data (either δ13Ccarb or δ13Corg) of many Triassic–Jurassic (T-J) sections have been acquired, paired δ13Ccarb and δ13Corg from continuous T-J carbonate sections, especially in eastern Tethys, have been scarcely reported. This study presents paired and decoupled δ13Ccarb and δ13Corg data from a continuous T-J carbonate section in Wadi Naqab. The T-J Wadi Naqab carbonate section, located in United Arab Emirates, Middle East, represents tropical and shallow marine sedimentation in eastern Tethys. At the T-J boundary interval, an initial carbon isotope excursion (CIE) is observed with different magnitude of isotope excursion and timing in δ13Ccarb and δ13Corg, while subsequently a positive CIE is only distinct in δ13Ccarb. Based on petrological, carbon isotope, Rock-Eval and elemental analyses, the δ13Ccarb is thought to record marine inorganic carbon, and the δ13Corg to record terrigenous organic carbon. Therefore, the paired δ13Ccarb and δ13Corg herein potentially document simultaneous changes in T-J atmospheric and marine settings of eastern Tethys. Their decoupled behavior may likely be caused by different changes or evolution of carbon pool between marine and atmospheric settings. The initial CIE present in both δ13Ccarb and δ13Corg may indicate influence of isotopically light carbon release related to CAMP activity in both atmospheric and marine settings. The following positive CIE only in δ13Ccarb suggests relatively steady carbon isotope composition in atmosphere, but enhanced burial of isotopically light carbon in marine settings. Furthermore, the T-J carbonates in the studied section were possibly deposited in normal and oxic shallow marine conditions. Global correlation based on the Wadi Naqab section and other T-J sections suggests spatially different T-J environmental parameters: in eastern Tethys and western Panthalassa, oxic condition, lacking organic-rich sediment, weaker ocean acidification and less influence of isotopically light carbon are more prevalent; in western Tethys and ...