摘要
在松辽盆地中央坳陷带龙虎泡—大安阶地与西部泰康隆起的交界处青山口组二三段高二、高一砂岩组发现了一种特殊的沉积——核形石,最典型的核形石产在杜30井的青山口组二三段(Qn2+3)。发育核形石的层段厚度约40cm,产出深度为1415.36～1415.77m。核形石颜色以灰色、棕褐色为主,有球状、椭球状、扁球状和不规则状。通过研究认为,本区核形石形成环境主要有两种:三角洲前缘水下分流间湾相带及滨浅湖滩坝相带。青山口组沉积期为湖盆萎缩期,随着相带向湖盆内(研究区东南方向)的迁移,核形石发育层位也向上迁移,表现出良好的环境指示意义。较少的陆源供给、较深的水体、温暖的气候、波动的水体环境都为介形虫的发育及核形石的物质沉淀、滚动生长提供了优良的条件。于是,核形石在小林克—齐家地区青山口组大量成层发育。
A kind of sedimentary oncolitic limestone was discovered at the boundary of Longhupao--Da＇an rank ground and Taikang uplift zone of middle depression in Songliao Basin. The typical oncolite was found to occur at the second and third sections （Qn^2＋3） of the Early Cretaceous Qingshankou Formation of Du30 well. The oncolite limestone layer is approximately 40cm in thickness, 1415. 36 - 1415. 77 m in depth. Oncolite is predominantly gray and brown, globosity, ellipsoid, oblatus and tuberose in shape. Our research suggests that there are primarily two environments for the formation of oncolite in this area： underground shallow bay facies of lake delta front and sand and dam facies of the brink and shallow lake. The Qignshan Group started to deposit at the period of the basin lake shrinking. As the facies zone migrated southeastward, horizons in which oncolite developed also moved upward, and this is good indicative of environment. Less terrestrial supply, deep water body, warm climate and undulatory water environment all provide oncolite with favorable conditions, resulting in large-scale development of oncolite in the Qingshankou Formation of the Xiaolinke--Qijia area.
出处
《地质学报》
EI
CAS
CSCD
北大核心
2009年第4期558-569,共12页
Acta Geologica Sinica
基金
国家重点基础研究计划“973”项目(编号2006CB202406)
教育部博士点基金(编号20050425515)资助的成果
