大港探区早古生代碳酸盐岩中方解石脉特征

Calcite Veins Characteristics in Early Palaeozoic Carbonate Rock in Dagang Region

碳酸盐岩是一种硬度低、抗剪切能力差、易溶解的岩石，内部易存在大量的各种类型的裂隙。利用岩石学和地球化学手段，对大港探区的寒武─奥陶纪碳酸盐岩中的裂隙进行了研究：碳酸盐岩中存在三种类型的脉体，脉体的充填方式和脉体的地球化学特征、充填时间都有明显的差异。脉体的形成一方面受大地构造活动的影响，同时也受大气水及火山热液的控制，并与地球动力学演化有密切的关系。Ⅰ型脉体形成与裂谷作用之前，与海水有关；Ⅱ型脉体也形成与裂谷作用之前，但与淡水作用有关；Ⅲ型脉体形成于同裂谷或裂谷作用后，与火山热液作用有关。

Carbonate rock is broken and dissolved easily in which there are lot of fractures and veins. Three kinds of calcite veins are found in early Palaeozoic carbonate rock of Dagang region. Every kind of veins has own petrology and geochemistry characteristics and related to the evolutions of geodynamics in Dagang region. The vein Ⅰ is formated before rifting and re-lated to sea water. The vein Ⅱ is formated before rifting and related to sea water and atmo-spheric water . The vein III is formated in synrifting or after rifting and related to volcanic geothermal solution.