黔中下二叠统碳酸盐岩中的构造-埋藏热液白云化作用

STRUCTURAL-BURIAL HYDROTHERMAL DOLOMITIZATION IN THE LOWER PERMIAN CARBONATE ROCKS IN CENTRAL GUIZHOU

上扬子地区下二叠统碳酸盐岩中,不同程度地发育一种中—粗晶白云岩或云灰岩,人们俗称为“糖粒状”白云岩。80年代以来,其成因多被解释为淡水透镜体模式形成的混合水白云化。笔者1987—1988年对黔中织金、清镇、黔西等地十余个剖面详细观察和室内薄片、扫描电镜、碳、氧同位素、有序度、包体均一温度的综合研究,结合该区地质演化分析,认为这类白云岩的成因当属埋藏过程中受构造活动影响的热液作用所致。一、“糖粒状”白云岩的产状与分布规律黔中地区下二叠统中—粗晶白云岩或云灰岩,多以似层状、巨厚块状(可达40m)。

It is suggested that thick massive, stratoid and patched medium-and coarse-grained dolostones result from structural processes and hydrothermal dolomitization rather than the products of mixed-water dolomitization formed according to the current fresh-water lens model on the basis of field occurrences and microscopic and eletron microscopic analyses, oxygen and carbon isotopes, ordering and homogenization temperatures of the inclusions, in conjunction with geological evolution. The porosity of this kind of the dolostones may be great enough to serve as the oil reservoirs. It is expected to prospect and explore oil and gas deposits of porosity and porosity-fissure types in the subsurface Lower Permian dolostones.