Paleo-Environments and Development Pattern of High-Quality Marine Source Rocks of the Early Cambrian, Northern Tarim Platform

被引：8
作者：
Fan Q. [1 ,2 ,3 ]
Fan T. [2 ,3 ]
Li Y. [2 ,3 ]
Zhang J. [4 ]
Gao Z. [2 ,3 ]
Chen Y. [5 ]
机构：
[1] CNOOC Research Institute Company Limited, Beijing
[2] School of Energy Resources, China University of Geosciences, Beijing
[3] Key Laboratory of Marine Reservoir Evolution and Hydrocarbon Enrichment Mechanism, Ministry of Education, Beijing
[4] Nanjing Institute of Geology and Paleontology, Chinese Academy of Sciences, Nanjing
[5] Wuxi Branch of Institute of Petroleum Exploration and Development, SINOPEC, Wuxi
来源：
Diqiu Kexue - Zhongguo Dizhi Daxue Xuebao/Earth Science - Journal of China University of Geosciences | 2020年 / 45卷 / 01期
关键词：
Cambrian; Hydrothermal; Paleo-environments development pattern; Petroleum geology; Source rocks; Tarim;
D O I：
10.3799/dqkx.2018.128
中图分类号：
学科分类号：
摘要：
The lower Cambrian Yuertusi Formation has been confirmed as the best high-quality source rocks of marine rocks in China, and the source rocks of the Cambrian pre-salt play in the Tarim and crucial research field of the Ediacaran-Cambrian transition. However, little work has been published about the paleo-environments. Yutixi section in Keping is intensively investigated by a multi proxy analysis including thin-sections identification, major elements, trace elements and TOC contents, for revealing the accumulation mechanisms of the sources rocks in this study. Results demonstrate that the samples are rich in trace elements comprising V, U, Ni, Ba, Mo, Cu and Zn. Along with the weakly positive Ce anomalies (Ce/Ce*=0.45), extremely positive Eu anomalies (Eu/Eu*=35.32), Y/Ho (39.77) and barite for samples of basal Yuertusi Fm., the REEs patterns of negative Ce anomalies, positive Y anomalies and positive Eu anomalies verified the drastic hydrothermal activities and anoxic conditions of the Early Cambrian. Specifically, many proxies including U/Al, V/Al, Th/U, V/Sc, and Mo-U covariation ascertained the paleocean in the northern Tarim was an open sea. The paleocean was under sulfide in period of Yuertusi Fm. Group A (Th/Uavg=0.070). Then it changed into suboxic in periods of Yuertusi Fm. Group B (Th/Uavg=1.21), Group C (Th/Uavg=0.62) and Group D (Th/Uavg=1.21) with generally increased oxidation level. Finally it was under sulfide conditions in period of Xiaoerbulake Fm. (Th/Uavg=0.13). In addition, the elevated productivity and well preservation are implied by the high TOC contents (TOCmax=17.2%) and ex-Baavg (8 634.85×10-6) for Yuertusi Fm. Group A. Ultimately, development pattern of the source rocks of the Lower Cambrian Yuertusi Fm., northern Tarim platform is proposed, which is characterized by hydrothermal activities, coastal upwelling and anoxic to sulfide conditions. This study will facilitate both the prospect evaluation of deep and super-deep oil and gas resources in Tarim basin, and studies of Ediacaran-Cambrian paleo-environments transition in NW China. © 2020, Editorial Department of Earth Science. All right reserved.
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页码：285 / 302
页数：17
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