塔里木盆地西部东河塘组的地层时代和物源研究

    The stratigraphic age and detrital provenance evolution of the Donghetang Formation in the western Tarim Basin

    • 摘要: 塔里木盆地作为我国重要油气勘探开发研究区之一,其经历了复杂的构造演化过程。但目前已有研究对盆地中西部地区志留系-泥盆系的潜在储油层认识不足。本文以巴探6井、康探1井和玉2井东河塘组岩芯样品作为研究对象,综合砂岩的碎屑组分、重矿物、碎屑锆石U-Pb年龄与稀土元素等研究手段,识别东河塘组的沉积特征、时代归属及其物源演化。研究表明,东河塘组属于滨-浅海砂质海岸相,地层时代为早泥盆世早期。碎屑锆石U-Pb年龄分为485-393 Ma,995-665 Ma,2064-1560 Ma三组;重矿物和碎屑锆石显示其母岩主要为酸性岩浆岩,少部分为中基性的岩浆岩或花岗伟晶岩;物源主要来自于西昆仑造山带和塔北隆起。通过厘定塔里木盆地西部泥盆系东河塘组沉积特征、地层归属与物源演化,不仅可以为盆地及其周缘演化提供资料,还可以为后期油气勘探提供数据支持。

       

      Abstract: The Tarim Basin, situated as a significant oil and gas exploration and development research region within China, has undergone a multifaceted tectonic evolution over time. Nonetheless, the existing studies have not adequately acknowledged the potential reservoirs within the Silurian-Devonian system in the central and western sectors of the basin. In this research paper, our focus is on core samples extracted from the Donghetang Formation, obtained from Batan 6 well, Kangtan 1 well and Yu 2 well. Our objective is to identify the depositional characteristics, material source evolution and age attribution of the Donghetang Formation. This analysis combines various factors, including the clastic fractions of sandstones, heavy minerals, zircon U-Pb ages, and rare earth elements. Our study reveals that the Donghetang Formation belongs to the coastal-shallow sandy coastal phase. The zircon U-Pb ages are distributed into three groups: 485-393 Ma, 995-665 Ma, and 2064-1560 Ma. Heavy minerals and detrital zircon data show that the host rocks are primarily composed of acidic magmatism, with a smaller presence of intermediate-basic magmatism or granitic pegmatites. The sources of the Donghetang Formation are primarily attributed to the West Kunlun Orogenic Belt and the Tabei Uplift. By comprehensively determining the sedimentary features, stratigraphic assignment, and source evolution of the Devonian Donghetang Formation in the western Tarim Basin, we can not only provide information on the evolution of the basin, but also provide crucial data support for future oil and gas exploration endeavors.

       

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