气候变化领域集成服务门户(CCPortal): Controls on organic matter enrichment of the early-middle Miocene lacustrine oil shale, central Tibet (SW China): New insights from clay minerals and geochemistry

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DOI	10.1016/j.jseaes.2024.106007
	Controls on organic matter enrichment of the early-middle Miocene lacustrine oil shale, central Tibet (SW China): New insights from clay minerals and geochemistry
	Zeng, Shengqiang; Wang, Jian; Fu, Xiugen; Feng, Xinglei; Wang, Dong
发表日期	2024
ISSN	1367-9120
EISSN	1878-5786
卷号	262
英文摘要	The Lunpola oil shale is the largest lacustrine oil shale deposit in Tibet (SW China), which deposited in a Cenozoic lacustrine rift basin and contains abundant organic matter (OM), whereas the crucial factors that controlled the OM enrichment remain elusive. Here, we present new datasets of total organic carbon (TOC) contents, clay minerals and whole-rock geochemistry of the early-middle Miocene Middle Dingqinghu Formation oil shale from the Lunpola basin, central Tibet, in order to elucidate the paleoclimate, paleo-environment condition and the controlling factors on the OM enrichment of the lacustrine oil shale. Oil shales from the Lunpola East section have high TOC contents (avg. 9.60%), while the contiguous mudstones contain low TOC contents (avg. 0.44%). During the oil shale deposition, high smectite and kaolinite contents, low illite contents and low Sr/Cu ratios suggest strong chemical weathering and hence warm and humid climate, which may probably have close relationship with the mid-Miocene climatic optimum (MMCO). However, during the mudstone deposition, the relatively high illite and low smectite contents and higher Sr/Cu ratios suggest weak chemical weathering, indicating relatively arid climatic condition. The paleo-environment indexes (C-org/P, Mo-EF and U-EF) and Mo-EF-U-EF covariation reflect an anoxic bottom water condition during the oil shale deposition, while the mudstone formed in oxic-dysoxic water environment. The weak and moderate positive relationship between bio-productivity proxies (P/Ti and Cu/Ti ratios) and TOC contents reveal that the bio-productivity condition is not the crucial factor for the OM enrichment. Moreover, the water column environment was brackish and stratified during the oil shale deposition, and the sedimentation rate was moderate, which were also conducive to the OM preservation. The positive correlations between the TOC and the paleoclimate and paleoenvironment proxies demonstrate that warm and humid climate during the MMCO and anoxic water conditions play predominant roles in OM enrichment of the Lunpola lacustrine oil shale. Besides, modest sedimentation rate can prevent the dilution of OM, which can also promote the OM enrichment. This study can not only deepen the understanding of OM enrichment mechanism in lacustrine rift basin but also provide important information for predicting the distribution of the oil shale in the Lunpola Basin.
关键词	Palaeoclimate Organic matter enrichment Oil shale Early-middle Miocene Lacustrine rift basin
英文关键词	MARINE BLACK SHALES; LUNPOLA BASIN; PALEOCLIMATIC INTERPRETATION; SEDIMENTATION-RATE; PALYNOLOGICAL EVIDENCE; APPALACHIAN BASIN; CARBON CONTENT; QAIDAM BASIN; PRESERVATION; ANOXIA
WOS研究方向	Geosciences, Multidisciplinary
WOS记录号	WOS:001158936500001
来源期刊	JOURNAL OF ASIAN EARTH SCIENCES
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/283249
作者单位	China Geological Survey; Chengdu Center, China Geological Survey; Ministry of Natural Resources of the People's Republic of China; Southwest Petroleum University; China Geological Survey; Chengdu Center, China Geological Survey
推荐引用方式 GB/T 7714	Zeng, Shengqiang,Wang, Jian,Fu, Xiugen,et al. Controls on organic matter enrichment of the early-middle Miocene lacustrine oil shale, central Tibet (SW China): New insights from clay minerals and geochemistry[J],2024,262.
APA	Zeng, Shengqiang,Wang, Jian,Fu, Xiugen,Feng, Xinglei,&Wang, Dong.(2024).Controls on organic matter enrichment of the early-middle Miocene lacustrine oil shale, central Tibet (SW China): New insights from clay minerals and geochemistry.JOURNAL OF ASIAN EARTH SCIENCES,262.
MLA	Zeng, Shengqiang,et al."Controls on organic matter enrichment of the early-middle Miocene lacustrine oil shale, central Tibet (SW China): New insights from clay minerals and geochemistry".JOURNAL OF ASIAN EARTH SCIENCES 262(2024).