塔里木盆地沙雅隆起与柯坪露头中上奥陶统地层对比及烃源岩分布

Stratigraphic correlation and source rock distribution of the Middle-Upper Ordovician in the Shaya Uplift and Kalpin outcrop, Tarim Basin

刘存革 李国蓉 罗明霞 邵小明 罗鹏 刘永立 高利君

Liu Cunge Li Guorong Luo Mingxia Shao Xiaoming Luo Peng Liu Yongli Gao Lijun

成都理工大学油气藏地质及开发工程国家重点实验室, 成都 610059 2. 中国石化西北油田分公司勘探开发研究院, 乌鲁木齐 830011

State Key Laboratory of Oil and Gas Reservoir Geology and Exploitation, Chengdu University of Technology, Chengdu, Sichuan 610059, China 2. Institute of Exploration and Development, SINOPEC Northwest Oilfield Company, Urumqi, Xinjiang 830011, China

柯坪露头奥陶系地层是塔里木盆地大型碳酸盐岩台地的西延部分,两者经历了相同的沉积演化过程。以古生物资料为基础,通过碳同位素地层对比,认为沙雅隆起中奥陶统一间房组发育的中达瑞威尔阶碳同位素正漂移(MDICE)和上奥陶统良里塔格组内发育的凯迪阶早期古登伯格碳同位素正漂移(GICE),分别对应于柯坪露头萨尔干组下部和其浪组中下部的正漂移,推测其浪组上部存在加里东中期Ⅱ幕构造运动的不整合面,不整合面之上的其浪组和印干组地层对应于沙雅隆起上奥陶统桑塔木组。受早-中奥陶世全球海平面上升的影响,塔里木盆地北部中下奥陶统台地东侧表现为陡坡,台地厚度向西北逐渐减薄,沙雅隆起西北地区和阿瓦提-柯坪北部地区属于斜坡-盆地沉积体系。萨尔干组海相烃源岩主要由达瑞威尔阶中晚期凝缩段沉积构成,结合露头和沙雅隆起钻井电性特征,认为该套烃源岩在阿瓦提和沙雅隆起西北地区也有分布。良里塔格组沉积时期,柯坪、塔中和沙雅隆起小型碳酸盐岩台地之间的凹陷是GICE对应的良里塔格组烃源岩有利发育地区。印干组烃源岩分布范围最广,在阿瓦提和沙雅隆起均有分布。

The Ordovician strata in the Kalpin outcrops are the westward extension of a large carbonate platform in the Tarim Basin, and they have experienced the same sedimentary evolution process as the basin. Based on biostratigraphy and carbon isotope stratigraphic correlation, the Middle Darriwilian Isotope Carbon Excursion (MDICE) of the Middle Ordovician Yijianfang Formation and the Guttenberg Isotope Carbon Excursion (GICE) of the Upper Ordovician Lianglitag Formation of the Shaya Uplift correspond to the positive excursions in the lower part of the Salgan Formation and the lower-middle parts of the Qilang Formation in the Kalpin outcrops, respectively. It was inferred that an unconformity of the second episode tectonic movement of the Middle Caledonian existed in the upper part of the Qilang Formation, and the Qilang and Yingan formations above the unconformity corresponded to the Sangtamu Formation of the Upper Ordovician in the Shaya Uplift. The eastern side of the Lower-Middle Ordovician platform in northern Tarim showed a steep slope due to the rise of global sea level in the Early-Middle Ordovician, and the platform thickness gradually thinned to the northwest. The northwestern Shaya Uplift and the Awat-northern Kalpin region belong to the slope to basin sedimentary system. The Salgan marine source rocks mainly comprise the condensed section of the middle-upper Darriwilian, and are distributed in the Awat and the northwestern Shaya uplift as indicated by the electrical characteristics of outcrops and drill cuttings. The depression between the small carbonate platforms of Kalpin, central Tarim and Shaya Uplift are favorable development regions of source rocks corresponding to GICE during the deposition of the Lianglitag Formation. The Yingan source rocks are most widely distributed in the Awat and Shaya uplift.

国家科技重大专项(2011ZX05005-004、2016ZX05005-002)和国家重点基础研究发展计划(973计划)项目(2012CB214806)资助。

https://doi.org/10.11781/sysydz201602170