华南地洼阶段古岩溶沉积建造

华南碳酸盐岩地区,广泛分布大小不等、形态务异,以钙屑砾岩和角砾岩等组成的地质体。这中生代岩溶凹陷和洞穴中的洞穴堆积物--占岩溶沉积岩。有两个岩溶作用期:地洼初动期期,洞穴堆积物的时代,分别相当于白垩纪-早第三纪,晚三叠世-中侏罗世。地洼初动期岩溶沉积体,有广泛的矿化,如Cu、Zn、Sb、Mo、Ag、Au、Pb、U等、在我国尚属新类型矿床。

Palaeo- Karst Sedimentary Formation of Diwa (Geodepression) Stage in Southern China

There are a good many geological bodies consist of calcite conglomerate and breccia etc.in the carbonate rock region of southern China, which are very complex and appear minor axis and random shapes on horizontal, their diameters reach several tens to thousands of meters, on section, they appear as columnar, tubal of reef-like shape etc. on the basis of detailed research of the geological bodies, the characteristics sedimentogenesis have been recognized in ancient karst depression of caves of Diwa (geodepression) stage. In southern China, the paoaeo-karstification can be devided into two periods: the preliminary-mobile and the climas-mobile period of Diwa development.their characteristics are shown in table 1. Palaeo-karst sedimentary rocks of Diwa stage are a set of unstable diamictite dominated by breccia and psephite.The rocks were formed by collapse, subsurface flow by gravity, underground lake and river and so on sedimentation. Pala -karst sedimentary bodies are dispersed in Diwa, existed in palaeo-superimposed depression which was formed in Diwa stage by multi-karstification.The depression imagines in satellite or aero photograph are as ringlike diagram. Palaeo-karst sedimentary rocks have been widely grown metasomasised by petrogenetic and later period actions, except for syngenetic and petrogenetic dolomitization, auto-silicificatin and calcitization-calcite recrystallization are mainly in them.