碳酸盐岩岩溶作用的元素地球化学表征--以塔河1号的S60井为例

通过对塔河地区奥陶系碳酸盐岩及其胶结物方解石的化学成分及方解石晶体微形貌研究后认为 :塔河一号S6 0井埋深 5 433.2 0～ 5 435m发育的岩溶角砾灰岩,属于高度大于 2m的大型古岩溶洞穴沉积;而埋深 5 435m中晶洞中的方解石是地表岩溶带的早中期的淡水与海水的混合带的产物。在本文中,作者指出碳酸盐岩矿物学及地球化学可有效地应用于表生岩溶作用中的深度、强度、期次以及成岩序列及古沉积环境判别等项研究中。

Element Geochemical Implications for Carbonate Karstification Interpretation --Taking Well S60 in Taihe as an example

Paleocave systems form an important type of carbonate reservoirs. The studies illustrates that there are widely developed passage caves in the Middle-Upper Ordovician carbonate of Taihe, including branchwork passage, network maze, anastomotic maze, spongework maze and ramiform maze as desoribed by Robert.G.L(1999), and near-surface solution enlarged fractures, sedimentation, rebrecciated chaotic breakdown and collapse as well as mechanical compaction in burial process are probably associated with the formation of collapsed-paleocave system. The approach in terms of chemical composition of carbonate and calcite cement samples and micrographology of calcite crystals associated with karstification has been carried out in Ordovician carbonate of well S60 in Taihe. The results indicates that the carbonate breccias,fractures and sediment fill well developed at the depth of 5 433.20 m～5 435 m belonging to a large-scale paleocave system sedimentation with more than 2 m in height; while the calcites grown in caves at the depth of 5 435m are the products of mixed zone of hypergen fresh water and seawater at the early-middle stage of near-surface karst terrain. Moreover, The author believe that the mineralogic and geochemical studies on carbonate karst process have an important implication for the uncovering the effective depth,periods and intensity of epigenic karst process as well as diagentic sequence and sedimentary environment.