气候变化领域集成服务门户(CCPortal): Biogenic silica and organic carbon fluxes provide evidence of enhanced marine productivity in the Upper Ordovician-Lower Silurian of South China

CCPortal

DOI	10.1016/j.palaeo.2019.109278
	Biogenic silica and organic carbon fluxes provide evidence of enhanced marine productivity in the Upper Ordovician-Lower Silurian of South China
	Khan M.Z.; Feng Q.; Zhang K.; Guo W.
发表日期	2019
ISSN	0031-0182
卷号	534
英文摘要	Biogenic silica is a powerful palaeoproductivity proxy in palaeomarine environments and is significant within shale gas reservoirs, demonstrating the association of marine hydrocarbon source rocks with the abundance of micro-siliceous fossils, yet detailed studies that investigate this strong alliance in the Ordovician-Silurian transition are still lacking. The bulk of TOC in marine sediments is commonly assumed to have been derived predominantly from marine phytoplankton, with modern ocean surveys indicating good correspondence between silica content and primary productivity. This study discovers a strong positive correlation between biogenic silica (Bio-Si) and TOC in the Upper Ordovician-Lower Silurian Wufeng and Longmaxi formations of South China in the Jiaoye 41-5 (R = +0.68, p(α) < 0.01, n = 69) and Jiaoye 51-2 (R = +0.68, p(α) < 0.01, n = 48) cores, implying that enhanced marine productivity has a strong effect on organic carbon enrichment. Geochemical and palaeontological analyses revealed that silica within these shales generally had a biogenic origin in Jiaoye 41-5 and Jiaoye 51-2, subsequently modified by silica dissolution and re-crystallization of radiolarians and sponge spicules. Palaeoproductivity proxies, including biogenic silica, barium, phosphorous, copper and nickel, were applied, together with the occurrence of pyritized or “ghost” radiolarians, to confirm high palaeoproductivity in the O-S transition. Synchronous OCAR and Bio-SiAR profiles imply that silica originating from siliceous organisms (Bio-Si) served as a likely vector for organic carbon enrichment in the Palaeozoic Wufeng-Longmaxi marine siliceous source rock, providing two possibilities: (i) the abundance of radiolarians was linked to algal proliferation, and consequently, high productivity resulted in a large organic carbon flux and/or (ii) radiolarians contributed to TOC (supported by studies revealing that modern radiolarians exhibit lipid contents of up to 47%). © 2019 Elsevier B.V.
英文关键词	Palaeoproductivity proxies; Radiolarians; Redox conditions; Total organic carbon; Wufeng-Longmaxi formations
语种	英语
scopus关键词	abundance estimation; biogenic deposit; biostratigraphy; carbon flux; dissolution; lipid; Ordovician; organic carbon; paleoproductivity; radiolarite; redox conditions; shale gas; silica; Silurian; China; Longmen Mountains; Taiwan; Wufeng; algae; Radiolaria (protozoans)
来源期刊	Palaeogeography, Palaeoclimatology, Palaeoecology
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/150797
作者单位	State Key Laboratory of Geological Processes and Mineral Resources, China University of Geosciences, Wuhan, Hubei 430074, China; School of Earth Science, China University of Geosciences, Wuhan, Hubei 430074, China
推荐引用方式 GB/T 7714	Khan M.Z.,Feng Q.,Zhang K.,et al. Biogenic silica and organic carbon fluxes provide evidence of enhanced marine productivity in the Upper Ordovician-Lower Silurian of South China[J],2019,534.
APA	Khan M.Z.,Feng Q.,Zhang K.,&Guo W..(2019).Biogenic silica and organic carbon fluxes provide evidence of enhanced marine productivity in the Upper Ordovician-Lower Silurian of South China.Palaeogeography, Palaeoclimatology, Palaeoecology,534.
MLA	Khan M.Z.,et al."Biogenic silica and organic carbon fluxes provide evidence of enhanced marine productivity in the Upper Ordovician-Lower Silurian of South China".Palaeogeography, Palaeoclimatology, Palaeoecology 534(2019).