Xu Xuhui, Chen Qianglu, Chu Chenglin, Li Guorong, Liu Cunge, Shi Zheng
Wuxi Research Institute of Petroleum Geology, SINOPEC, Wuxi, 214126 Jiangsu China.
Energy Resources of Chengdu University of Technology, Chengdu, 610059 Sichuan China.
Carbonates Evaporites. 2017;32(4):487-496. doi: 10.1007/s13146-016-0307-4. Epub 2016 Jul 14.
Thick carbonate rocks were developed in the depression of the Tarim craton during the Cambrian-Middle Ordovician periods. The compressional tectonic movement during the Middle Caledonian-Hercynian created the paleouplifts, which became the base for the paleokarst in the Ordovician carbonate rocks. Based on the large quantity of seismic, drilling, and geological outcrop data, this study analyzed the paleokarst development in relation to the multi-stage tectonic movements in the Paleozoic Era and different stages of karstification and hypothesized paleogeomorphology and paleokarst water system of those stages. Fractures from the tectonic movements in the carbonate and non-carbonate rocks were essential for water cycle, and therefore, the karst development in deep carbonate rocks. Paleokarsts in the Tarim Basin can be classified into four major types based on the paleogeomorphology, degree of karstification, and the layering, i.e., Tahe type, gentle hill type, high steep hill type, and covered-semi-open type. Relatively, the Tahe type was mostly on hill slopes and had the strongest karstification, the gentle hill type often located in the plain areas or basin bottoms and had least karstification, the high steep hill type was controlled by faults and had medium karstification, the semi-open type was controlled by precipitation and hydraulic gradient, and fracture passages and karst caves were mostly developed along major fractures. Overall, the paleokarsts of the Ordovician carbonate rocks in the Tarim Basin can be characterized by long geologic history, multiple development stages, deep burial depth, and various karst types.
寒武纪—中奥陶世期间，塔里木克拉通坳陷发育了厚层碳酸盐岩。中加里东期—海西期的挤压构造运动造就了古隆起，成为奥陶系碳酸盐岩古岩溶作用的基础。本研究基于大量地震、钻井及地质露头资料，分析了古岩溶发育与古生代多期构造运动及不同岩溶作用阶段的关系，并对各阶段的古地貌及古岩溶水系统进行了推测。碳酸盐岩和非碳酸盐岩构造运动形成的裂缝对水循环至关重要，进而对深部碳酸盐岩岩溶发育也至关重要。塔里木盆地的古岩溶根据古地貌、岩溶作用程度及分层情况可分为4种主要类型，即塔河型、缓丘型、高陡丘型和覆盖—半裸露型。相对而言，塔河型多位于山坡，岩溶作用最强；缓丘型常位于平原区或盆地底部，岩溶作用最弱；高陡丘型受断层控制，岩溶作用中等；半裸露型受降水和水力梯度控制，裂缝通道和溶洞多沿主要裂缝发育。总体而言，塔里木盆地奥陶系碳酸盐岩古岩溶具有地质历史长、发育阶段多、埋藏深度大、岩溶类型多样的特点。
