八道湾组地层特征和沉积相特征

Stratigraphic Characteristics and Sedimentary Facies Characteristics of Badaowan Formation

摘要: 本论文以准噶尔盆地昌吉地区西南部为研究对象，通过野外实测剖面及前人的研究成果，对研究区进行岩相学、沉积学研究，并结合C-O同位素方法进行综合研究。通过研究我们将八道湾组地层分为上下两段，下段岩性为浅灰绿色含砾粗砂岩、浅黄绿色中砂岩与细砂岩不均匀互层为特征，岩层厚度稳定，为中厚层状构造，发育水平层理；上段颜色以黄绿色与土黄色相间，岩性为细砂岩、粉砂岩与粉砂质泥岩互层，中薄层状构造，可见有机质团块及植物化石碎片。八道湾组C-O同位素测试结果表明成岩过程中以淡水为主，成岩时流体盐度低。八道湾组下段以湖相为主，其中湖相以滨湖相和浅湖相为主；上段以深湖相沉积为主，其间有少量滨浅湖相沉积。

Abstract: In this paper, the southwest of Junggar Basin in Changji area is taken as the research object, with the field measured geological section and the previous research results, the petrography and se-dimentology in this area are studied, and combined with the C-O isotope method to carry on the comprehensive research. Here, the Badaowan formation are divided into upper and lower mem-bers. The rock assemblage of the lower member is characterized by shallow grayish green gravel coarse sandstone, shallow yellow-green medium sandstone and fine sandstone, and these rocks are interbedded unevenly. The thickness of the stratum is stable, which is a medium and thick layer structure. The strata have horizontal bedding structural types. The color of the upper section is yellow-green and khaki-yellow, which alternate with each other. The rocks comprised of fine sandstone, siltstone and silty mudstone, that are interbedded with each other, with medium-thin layer structure. Organic matter mass and plant fossil fragments can be seen in this section. The results of C-O isotopic test of Badaowan formation show that fresh water is the main diagenetic process at that time, and the fluid salinity is low during diagenetic process. The lower member of Badaowan formation is mainly lacustrine facies, in which lacustrine and shallow lacustrine deposits are dominant, and the upper member is dominated by deep lacustrine deposits, during which there are a small amount of shoreline and shallow lacustrine deposits.