巴颜喀拉盆地长石头山二叠纪—三叠纪碳酸盐岩丘的沉积岩石学和地球化学特征

青海巴颜喀拉盆地长石头山二叠纪—三叠纪碳酸盐岩丘是由罕见的块状纯灰岩组成,灰岩具团块结构,由泥微晶方解石团块和栉状生长的泥微晶方解石胶结物组成,部分泥微晶方解石发生了重结晶作用。灰岩的矿物组成主要为方解石,平均含量达97%,化学成分除CaO外,其余均低于5‰。灰岩的5%HNO3可溶相(碳酸盐矿物)稀土元素页岩配分模式具有Ce负异常,与二叠纪海相灰岩、二叠纪海水和现代东太平洋海水基本一致。微量元素分析显示V/Cr比值极低,自生沉积的Uau仅为0.08～0.5μg/g,在还原环境中富集的元素U、V、Mo、Cr、Co、Cu和Zn含量偏低或缺失,表明碳酸盐岩可能是在开阔海氧化环境中的快速沉积产物。

上扬子地区震旦纪沉积古地理

通过整理大量的钻井、测井、地震和其他综合研究资料,系统编制了上扬子地区震旦系各层段的岩相古地理图,进行了较为系统的沉积储集层研究。该研究显示震旦纪上扬子台地是一个半孤立的台地。震旦系沉积可以划分为前台地沉积、碳酸盐岩台地沉积和局限海盆沉积。紧邻上扬子台地西部边缘发育的川滇大裂谷对上扬子台地的演化、沉积古地理格局的形成及沉积相带的展布有着重要影响。灯影期,上扬子台地曾经有过一次由裂谷活动导致的快速沉降,经历了一次短暂的由台地到海盆的变化。岩相古地理的演变控制着四川盆地震旦系沉积储集层的形成与分布,也控制着该区常规油气及页岩气的形成与分布。

Structural Characteristics of Paleozoic and Geological Significance of Oil and Gas of Dongpu Depression

The Dongpu depression has experienced a complicated evolution of structure since Mesozoic. The Paleozoic carbonate rock has been strongly reformed and the buried hills with different characteristics of structure are developed in the depression. There exist lots of groups of fault structures with strikes of NNE(or NE),NW, near NS and EW etc., of which the faults with strikes of NNE and NW play an important controlling role on present-day structural framework of the depression. The faults with near NS-striking and EW-striking deeply affect the establishment of structural framework of basement of the depression. Although most of the fractures are filled by calcite and other minerals, under the action of later structural stress, the earlier fractures could change their features into tensional ones. Therefore, much attention should be paid to the exploration and exploitation of Paleozoic oil and gas in Dongpu depression.