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

• 作者: Yuzhu Ge
• 来源期刊: 地学前缘（英文版）
• 年，卷（期）: 2021,（4）
• 所属期刊栏目: Research Paper
• 页码范围: 175-184
• 页数: 10页
• 语种: 英文

摘要

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 re-ported.This study presents paired and decoupled δ13Ccarb and δ13Corg data from a continuous T-J carbonate sec-tion in Wadi Naqab.The T-J Wadi Naqab carbonate section,located in United Arab Emirates,Middle East,represents tropical and shallow marine sedimentation in eastem Tethys.At the T-J boundary interval,an initial carbon isotope excursion (ClE) is observed with different magnitude of isotope excursion and timing in δ13Ccaro and δ13Corg,while subsequently a positive OE is only distinct in δ13Ccarb.Based on petrological,carbon iso-tope,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 si-multaneous 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 re-lated to CAMP activity in both atmospheric and marine settings.The following positive CIE only in δ13Ccarb sug-gests 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 nor-mal and oxic shallow marine conditions.Global correlation based on the Wadi Naqab section and other T-J sec-tions suggests spatially different T-J environmental parameters:in eastern Tethys and westem Panthalassa,oxic condition,lacking organic-rich sediment,weaker ocean addification and less influence of isotopically light car-bon are more prevalent;in western Tethys and eastern Panthalassa,oxygen-depleted condition,black shales,stronger acidification and heavier influence of isotopically light carbon are more prevalent.These differences may be related to spatial distance from the CAMP or to different paleogeography.