天津蓟县雾迷山组高频旋回沉积特征  

Study on the Sedimentary Features of High Frequency Cyclothems of the Wumishan Formation at Jixian,Tianjin

作　　者：周洪瑞[1] 梅冥相[1] 杜本明[1] 罗志清[1] 吕苗[1] 

机构地区：[1]中国地质大学地球科学与资源学院,北京100083

出　　处：《现代地质》2006年第2期209-215,共7页Geoscience

基　　金：高等学校博士学科点专项科研基金项目(20020491002);国家自然科学基金项目(40472065)

摘　　要：天津蓟县剖面的中元古界雾迷山组是一套厚达3 300 m的碳酸盐岩地层,其中广泛发育具有近似对称相序组构的雾迷山旋回层,属于特殊的环潮坪型碳酸盐米级旋回层序。在对旋回层内部岩石成因单元的类型及组合分析的基础上,建立了雾迷山旋回层的基本模式和沉积环境模式,并对成因单元的岩石磁化率特征及其对高频旋回的反映进行了探索。认为雾迷山旋回层为沉积环境的水深由较浅—较深—较浅—暴露条件下的沉积,可能代表真正的沉积旋回;其成因单元之间具有明显的有序叠置形态,表明它有可能是与米兰柯维奇旋回具有成因关联的高频率海平面变化所控制的自旋回沉积作用的产物。The Mesoproterozoic Wumishan Formation in Jixian, Tianjin represents a succession of carbonate strata with 3,300 m in thick, in which Wumishan cyclothems with approximately symmetrical lithofacies successions are the best developed. They are particularly meter-scale cyclic sequences of peritidal type. Based on the analysis of types and association of genetic units of lithofacies of the Wumishan cyclothems, the general and sedimentary models of the Wumishan cyclothems were established. The magnetic susceptibility of the genetic units and its relationship to the high frequency cyclothems were discussed. It is believed that Wumishan cyclothems were formed in the sedimentary environment change, i.e. water depth changed from shallow to deep, then to shallow, and to be instantaneously exposed at last. So it could be considered as a real sedimentary cycle. According to the vertical stacking patterns of the genetic units of lithofacies of the Wumishan cyclothems, it is concluded that the Wumishan cyclothems were probably formed by autocyclical deposition that was controlled by high frequency sea-level change related to the Milankevitch cycle.

关 键 词：雾迷山组 雾迷山旋回层 旋回沉积作用 中元古代 天津蓟县 

分 类 号：P539.2[天文地球—古生物学与地层学]