震旦纪灯影组磷块岩及其生成特点  

PHOSPHORITES OF DENGYING FORMATION DURING SINIAN PERIOD AND THEIR GENESIS

作　　者：赵东旭[1] 

机构地区：[1]中国科学院地质研究所,北京100029

出　　处：《岩石学报》1990年第3期87-96,T002,共11页Acta Petrologica Sinica

摘　　要：灯影组磷块岩有四种类型,即泥晶磷块岩、内碎屑磷块岩、藻磷块岩和细晶磷块岩。组成磷块岩的主要矿物是磷灰石、白云石、石英和少量伊利石等。磷块岩主要沉积在陆缘海内,它的沉积环境是与深水有联系的浅水地区。深水和浅水环境的地质背景分别为构造拗陷和碳酸盐岩台地。前者提供成矿物质,后者提供有利于磷质成矿的沉积环境。Of the phosphorites in Dengying Formation there are four types, viz., micritic, intraclastic, algal and finecrystal phosphorites. The major minerals making up the micritic phosphorite are micritic apatite and small amounts of illite and quartz. The micritic apatite was directly precipitated from marine water. The intraclastic phosphorite consists of phosphatic intraclasts and various cements or matrix. The intraclaste occurred in sedimentary basin due to the break of phosphatic deposit. The mineral constituents of the cement are sparry apatite, dolomite and quartz, which were precipitated from pore water between the intraclasts. The constituents of matrix are dolomite and illite. They deposited together with intraclasts at the same time. The algal phosphorite consists of phosphatic oncolite and micritic dolomite matrix. The finecrystal phosphorite was mainly produced by recrystallization of the micritic apatite and formed under the influence of siliceous solution. The phosphorites tended to deposit in the pericontinental sea, rather than in the epicontinental sea. In the pericontinental sea, phosphorite usually accumulated in the shallow water region associated with deep water. The background of deep and shallow water environments was tectonic depression and carbonate rock platform respectively. The former provided mineragenetic material, and the latter provided advantageous sedimentary environment for the mineralization of phosphate.

关 键 词：磷块岩 成岩作用 沉积 环境 震旦纪 

分 类 号：P588.244[天文地球—岩石学]