摘要：The continually-discovered large volumes of marine hydrocarbons indicate a huge exploration potential within the carbonate rocks of Ordovician in the Tarim Basin, northwestern China. The Middle-Upper Ordovician (O 2+3 ) carbonate source rocks are at a highly mature stage. These rocks presently contain a low amount of total organic carbon (TOC p d <= 0.5%) (TOC p d means the present-day TOC). A mass balance approach is used to identify the source rocks that have expelled hydrocarbons. The characteristics and origin of hydrocarbon expulsion from low-TOC pd source rocks are studied, which are signi ficant for oil exploration in the basin. The results showed that a low-TOC pd O 2+3 source rock having expelled hydrocarbons was type I and had a very narrow oil window. With a high rock maturity and a high original TOC (TOC o ) value exceeding 1%, nearly 80% of the generated hydrocarbons were expelled. The content of gammacerane and C 28 steranes in the oil and source rock extracts were relatively lean, with a V-shaped distribution of regular steranes, suggesting a possible genetic relation between the low-TOC pd source rocks and the marine oil in the Tabei area. Hydrogenrich planktonic algae or acritarchs were the main hydrocarbon parent materials, distributed in the subsiding platform-slope facies. Organic matter was preserved under reducing conditions, and source rocks were formed with a favorable kerogen type and a moderate hydrocarbon generation potential. This study illustrates the hydrocarbon expulsion of low TOC pd source rocks in northern Tarim Basin, which is greatly signi ficant for analyzing the genesis of marine crude oil in Tarim Basin, and evaluating the distribution of marine source rocks. This research method is theoretically signi ficant for oil and gas exploration in the same type of highlymature carbonate paleobasins.

关键字：Carbonate source rock; Mass balance approach; Present-day TOC; Genesis mechanism; Tarim Basin

ISSN号：2095-3836

卷、期、页：卷13期3: 594-619

发表日期：2024-07-01

期刊分区（SCI为中科院分区）：二区

收录情况：SCI（科学引文索引印刷版）,地学领域高质量科技期刊分级目录（国外T1）,SCIE（科学引文索引网络版）

发表期刊名称：JOURNAL OF PALAEOGEOGRAPHY-ENGLISH

参与作者：杨海军,谌卓恒

通讯作者：施砍园,张心罡,吴松

第一作者：陈君青,姜福杰,庞雄奇,庞博,庞宏,陈践发

论文类型：期刊论文

论文概要：陈君青,姜福杰,庞雄奇,杨海军,施砍园,庞博,庞宏,陈践发,谌卓恒,张心罡,吴松，Characteristics and origin of low-organicmatter carbonate source rocks in the Middle- Upper Ordovician, Tarim Basin, northwestern China，JOURNAL OF PALAEOGEOGRAPHY-ENGLISH，2024，卷13期3: 594-619

论文题目：Characteristics and origin of low-organicmatter carbonate source rocks in the Middle- Upper Ordovician, Tarim Basin, northwestern China