Different accumulation mechanisms of organic matter in Cambrian sedimentary successions in the western and northeastern margins of the Tarim Basin, NW China. (March 2021)

• Record Type: Journal Article
• Authors: Deng, Qian; Wang, Haozhe; Wei, Zhiwei; Li, Shida; Zhang, Haizu; Liu, Hu; Lekan Faboya, Oluwabamise; Cheng, Bin; Liao, Zewen
• Is Part Of: Journal of Asian earth sciences. Volume 207(2021)
• Publication Date: 2021-03
• Subjects: Organic matter accumulation -- Stable organic/inorganic carbon isotope distribution -- Lower Cambrian strata -- Tarim Basin; Earth sciences -- Asia -- Periodicals; Sciences de la terre -- Asie -- Périodiques; Earth sciences; Asia; Periodicals; 555.05
• DOI: 10.1016/j.jseaes.2020.104660
• Languages: English
• ISSNs: 1367-9120

Abstract

Graphical abstract: Highlights: The Lower Cambrian strata from the Tarim Basin margins are geochemically different. Different TOC/δ 13 Cker values were found from the western and NE Cambrian strata. The Lower Cambrian shale from both margins are rich in bio-essential trace elements. Both formations were deposited with high productivity under an anoxic condition. These two formations had different algae/detritus input with different TOC contents. Abstract: Lower Cambrian black shales are widely distributed in the Tarim Basin, but those in the Keping area in the west have a high total organic carbon (TOC) content different from those in the Kuluketage area in the northeast of the basin. The Cambrian Yuertusi Formation in the Shiairike section (Keping) and the Xishanbulake Formation in the Yaerdangshan section (Kuluketage) are time-equivalent and can be correlated. Black shales of the Yuertusi Formation have lower δ 13 CKer values (<−34‰) than the Xishanbulake Formations (δ 13 CKer values > − 4‰). These values suggest that black shales in the Yuertusi Formation were dominated by benthic algae, whereas rocks in the Xishanbulake Formation contain substantial amounts of planktonic algae. Analyses of trace elements demonstrate an anoxic depositional environment, with high productivity in both the Yuertusi and Xishanbulake Formations. The enhanced productivity was promoted by upwelling fluids and hydrothermal events, leading to the enrichment of nutrient elements such as barium, cadmium, copper, phosphorus, nickel, vanadium, and zinc. More terrigenous inorganic detritus input to the Xishanbulake Formation, which led to less amounts of organic matter and degradation of planktonic algae during sedimentation, resulted in a lower TOC content than the Yuertusi Formation.