气候变化领域集成服务门户(CCPortal): How marine incursion influences the quality of lacustrine source rocks: The Paleogene Nanxiang Basin, eastern China

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DOI	10.1306/101261817268
	How marine incursion influences the quality of lacustrine source rocks: The Paleogene Nanxiang Basin, eastern China
	Xia L.; Cao J.; Hu S.; Li S.
发表日期	2019
ISSN	0149-1423
卷号	103 期号:5
英文摘要	The impact of marine incursions during transgression (i.e., sea level rises and the shoreline moves landward) on the formation and quality of lacustrine source rocks is an important and contentious issue. In this study, we present a case study of the Paleogene Hetaoyuan Formation in the Biyang sag, Nanxiang Basin, eastern China. Paleontological, trace-element, and biomarker data indicate that the Hetaoyuan source rocks in this region were influenced by a marine incursion. The paleontological evidence indicates that the marine incursion resulted in the introduction of red and brown algae, which commonly inhabit marine environments. Trace-element analyses yielded representative evidence of marine incursion (e.g., equivalent boron content >300 ppm and B/Ga ratio >4.2). Biomarker evidence for marine incursion includes C26/C25 tricyclic terpanes ratios of 1:3, which is the threshold for distinguishing marine organic matter from lacustrine. Using the B/Ga ratio as a typical paleosalinity indicator, it was determined that the influence of marine incursion decreased from the Biye 1 to Cheng 2 to An 3006 wells, with the B/Ga ratio average decreasing from 7.51 to 6.81 to 3.73, respectively. With an increasing extent of marine incursion (e.g., distance landward, overall water depth, and marine–freshwater mixing), the primary productivity of organic matter increased, and the preservational environment became more reducing. These changes resulted in higher contents of organic matter (total organic carbon = 2–8 wt. %) and a more favorable type of organic matter for oil generation (kerogen type I–II), indicating that the marine incursion had a positive effect on the formation of source rocks. Therefore, the formation mechanism of high-quality source rocks in coastal lacustrine basins during high sea-level periods and associated resource potential might need to be reevaluated (e.g., the Campanian lower Neslen Formation along the margins of the Western Interior Seaway of North America and the terminal Oligocene–early Miocene in the fluvial Saldanha Bay at the southwestern tip of Africa). The results also provide useful data for regional oil and gas exploration. Copyright ©2019. The American Association of Petroleum Geologists. All rights reserved.
语种	英语
scopus关键词	Algae; Biogeochemistry; Biological materials; Biomarkers; Offshore gas fields; Organic carbon; Petroleum prospecting; Sea level; Trace elements; High-quality source rocks; Lacustrine source rocks; Oil and gas exploration; Paleontological evidence; Primary productivity; Resource potentials; Total Organic Carbon; Trace element analysis; Rocks; brown alga; Campanian; environmental quality; formation mechanism; hydrocarbon exploration; lacustrine deposit; marine environment; Miocene; Oligocene; Paleogene; red alga; sea level; source rock; Africa; China; Nanxiang Basin; North America; Saldanha Bay; South Africa; Western Cape; Western Interior; Phaeophyceae
来源期刊	AAPG Bulletin
文献类型	期刊论文
条目标识符	http://gcip.llas.ac.cn/handle/2XKMVOVA/125012
作者单位	State Key Laboratory for Mineral Deposits Research, School of Earth Sciences and Engineering, Nanjing University, Nanjing, Jiangsu, China; Department of Earth Resources, China University of Geosciences (Wuhan), Wuhan, Hubei, China
推荐引用方式 GB/T 7714	Xia L.,Cao J.,Hu S.,et al. How marine incursion influences the quality of lacustrine source rocks: The Paleogene Nanxiang Basin, eastern China[J],2019,103(5).
APA	Xia L.,Cao J.,Hu S.,&Li S..(2019).How marine incursion influences the quality of lacustrine source rocks: The Paleogene Nanxiang Basin, eastern China.AAPG Bulletin,103(5).
MLA	Xia L.,et al."How marine incursion influences the quality of lacustrine source rocks: The Paleogene Nanxiang Basin, eastern China".AAPG Bulletin 103.5(2019).