摘要
周口店地区广泛分布的寒武纪地层府君山组底部灰岩因其具典型的豹斑状构造而被称为豹皮灰岩。本文主要以出露于周口店黄院地区的豹皮灰岩为研究对象。组成豹皮灰岩的物质成分有2种,一为白云质成分的豹斑,其余部分为泥灰质。在露头尺度上,豹皮灰岩中的豹斑发生了明显的旋转变形并具有一定的定向性,而泥灰质成分则具有清晰的韧性变形特征,为较典型的碳酸盐糜棱岩;在微观尺度上,构成豹斑的白云石矿物未发生韧性变形,而泥灰质成分中的方解石具有明显的细粒化、拉长和定向。豹皮灰岩变形发生时岩石所处的温度介于200～250℃之间。豹皮灰岩的形成经历了原岩形成和后期构造变形改造2个阶段,于寒武纪由沉积作用形成了岩石的物质组分和原生层状构造,在前印支期受水平剪切作用形成岩石的豹斑状构造。
Limestone distributed widely at the bottom of the Cambrian Fujunshan Formation in the Zhoukoudian area is called leopard limestone because it has typical leopard-mottled structure. This study focuses on leopard limestone in the Huanyuan area, Zhoukoudian, Beijing. Leopard limestone is composed of dolomitic and marly materials. Motdes in leopard limestone have undergone rotational deformation and have certain preferred orientation, while the marly component shows distinct features of ductile deformation; it is relatively typical carbonate mylonite. At the microscopic scale, dolomite that forms leopard mottles has not undergone ductile deformation, but calcite in the marly component is obviously finely granulated, elongated and oriented. The temperatures at which leopard limestone was deformed ranged between 200 and 250℃. The formation of leopard limestone progressed through two phases： formation of the protolith and structural deformation and reworking in the late stage. In the Cambrian the material components and primary layered structure of the rock formed by sedimentation, and in the pre-Indosinian leopard structure formed by horizontal shear.
出处
《地质通报》
CAS
CSCD
北大核心
2007年第6期769-775,共7页
Geological Bulletin of China
基金
国家自然科学基金项目(编号:49802019和49702034)成果
关键词
北京周口店
豹皮灰岩
府君山组
寒武纪
韧性变形
碳酸盐糜棱岩
Zhoukoudian, Beijing
Cambrian
Fujunshan Formation
leopard limestone
ductile deformation
carbonate mylonite
