Sedimentary Characteristics and Origin of Lacustrine Mixed Rocks of the Second Member of the Eogene Shahejie Formation in Zhanhua Sag, Jiyang Depression: Taking Luojia——Shaojia Area for an Example
详细信息
- 责任者：Wang Jinyou (China University of Geosciences ; Beijing 100083 ; China) ; Zhang Liqiang
- 刊名：Geological Review
- 出版年：2013
- 卷期：59(6)
- 关键词：岩屑杂岩 ; diamictite ; 沉积环境 ; sedimentary environment ; 济阳坳陷 ; Jiyang Depression
- 页码：p.1085-1096
- 图表：7 illus., 25 refs.
- 分类号：0803
- issnNo：ISSN0371-5736
- isbnNo：CN11-1952/P
摘要
Mixed rock is a typical product of mixing deposits,but the research of mixed rock are in low degree. Located in the southern slope of Zhanhua Sag,Jiyang Depression,western Luojia—Shaojia area widely developed lacustrine mixed rocks throughout the Second Member of Shahejie Formation( Es2). This paper studied the mixed sedimentation in this area based on regional geological data,well logging data,observation of wells cores,indoor sample analysis. The results show that there are various types of mixed rocks in this area,which can be classified into two categories and four kinds. From bottom to top,the amount of mixed rocks increased gradually,and its range also expanded gradually. Mixing deposits with gradual changed facies——edge and mixing deposits caused by mutated events are the major genesis of the formation of mixed rocks,while some other genetic types also exist,such as autochthonous mixing deposits. Different types of mixing deposits usually overlap each other,and interlace frequently. In the study area,mixed rocks developed in lacstrine shoreland with input from two large provenances,and can be further classified into the following kinds: mud flat microfacies of mixing deposits,organic bank microfacies of mixing deposits, granular bank microfacies of mixing deposits, sandstone bar microfacies of mixing deposits,and so on. There are marked differences between mixed rocks formed in different environments in terms of their fabrics,types and vertical sequences. The development of the mixed rocks is mainly controlled by supplies from provenance and complicated hydrodynamic conditions,and secondly controlled by factors like structural settings and lake level changes,etc.