乌恰康苏河剖面上部沉积特征及其古海洋环境

Sedimentary Characteristics and Palaeo-Marine Environment of Upper Kangsu River Section in Wuqia

乌恰康苏河剖面位于我国油气勘探重点的塔里木盆地西南边缘,晚白垩世初期新特提斯洋海侵造成该区域发育大面积的海相沉积。本文以康苏河剖面为研究对象,开展岩石学、地球化学等方面的分析。依据岩石学和样品主、微量和稀土元素特征显示,研究区的沉积环境物源供应充分,母岩以沉积岩–花岗岩为主,伴有玄武岩,沉积环境为气候温暖、湿润、风化强烈、沉积速率较高、古生产力增加的浅海环境;应用TiO2-(Fe2O3 + MgO)、La-Th-Sc沉积构造背景判别图解得出,构造环境相对复杂,为大陆边缘沉积特征,且源岩类型主要为花岗岩与沉积岩的混合。

The Kangsu River section of Wuqia is located in the southwest margin of Tarim Basin which is the key oil and gas exploration area in China. The Neo-Tethys transgression in the early stage of Late Cretaceous resulted in the development of large area of Marine sediments in this area. In this paper, the Kangsu River section is taken as the research object to carry out petrological and geochemical analysis. According to petrology and the characteristics of major trace elements and rare earth elements of the sample, the sedimentary environment in the study area has sufficient provenance supply. The parent rocks are mainly sedimentary rock-granite accompanied by basalt, and the sedimentary environment is shallow sea environment with warm and humid climate, strong weathering and high deposition rate and increased palaeo-productivity;based on the discriminant diagram of TiO2-(Fe2O3 + MgO) and La-Th-Sc sedimentary tectonic background, the tectonic environment is relatively complex, the continental island arc type is dominant, and the sedimentary features of continental margin, and the source rock type is mainly the mixture of granite and sedimentary rock.