车镇地区下古生界碳酸盐岩潜山岩溶模式初探

Preliminary study on palaeokarst of lower Paleozoic carbonate buried hill in Chezhen area

构造分析和地层研究表明,潜山范围内岩溶垂向发育有限,但是潜山周缘岩溶深度很大。采用岩石学、地球化学分析等方法,对研究区岩溶作用进行了深入分析。共识别出3期岩溶作用,即寒武系冶里亮甲山组-凤山组沉积期岩溶、加里东期岩溶和印支燕山期岩溶。初步探讨了3期岩溶机制:沉积期古岩溶受控于沉积、成岩作用,以大气水、海水混合白云石化作用所形成的储集空间最为有利;加里东期古岩溶介质为大气水,以地表溶蚀为主,岩溶缝、孔、洞多为后期石炭-二叠系泥岩所充填;印支燕山期古岩溶为研究区主要岩溶发育期,受构造运动、内幕地层控制,岩溶介质主要为大气水,混有地下热液影响。

In Chezhen area the tectonic analysis and stratigraphic investigation show that the paleokarst depth within a buried hill is shallow, while the paleokarst depth along the periphery of the buffed hill is deep. Petrologic and geochemical methods are fully made use of to study the paleokarst, and three periods of paleokarst are recognized, i.e. the paleokarst during the sedimentation of the Yeliliangiiashan - Fengshan group, the Caledonian one, and the Indosinian - Yanshanian one. The paleokarst mechanism is then discussed. The paleokarst during the deposition was controlled by sedimentation and diagenesis. Its favorite accumulation space is formed by dolomitization, whose diagenetic fluid is rain and sea water. The Caledonian paleokarst is formed by rain water. Its paleokarst happened mainly on the surface of the zone, and the solution fracture, pore, and cavity are later filled with C - P mudstone. The Indosinian- Yanshanian one is the main paleokarst of the study area. It is controlled by tectonic movement and stratigraphy. The solution fluid is mainly rain water mixed with the hot water underground.