宁夏天景山奥陶系马家沟组、米钵山组常量、微量元素聚类分析成果解释

宁夏天景山—米钵山的马家沟组为一套台地碳酸盐岩沉积，米钵山组为一套台地前缘斜坡重力流沉积的碎屑岩夹泥质岩、碳酸盐岩。两组地层中主要氧化物和微量元素、稀土元素具有明显的时空演变规律。聚类分析表明，两组地层地球化学特征既有独立性，又有相关性。各组内部纵向上地球化学演化既有阶段性，又有一定的旋回性，表现为大多数元素和参数的同步增加或减少。这种时空演变规律与地层宏观特征相一致，与沉积环境相关连。

The geological interpretation on the results of cluster analysis of major and trace elements from the Ordovician Majiagou and Miboshan Formations in the Tianjing mountain area, Ningxia

The Ordovician strata occur widely in the Tianjing mountain area, Ningxia. The Majiagou Formation in this area is made up of a suite of platform carbonate sediments, whereas the Miboshan Formation consists of a suite of foreslope gravity flow sediments including clastic rocks intercalated with mudstone and carbonate rocks. The main oxides, trace elements and rare earth elements display a regular temporal and spatial evolution. The cluster analytical results show that geochemically the strata in the two formations are not only independent but also correlated. Vertically, the geochemical signatures of these strata also exhibit an episodic and cyclic pattern of evolution, i.e. the simultaneous increase or decrease in most of the elements and parameters. In this respect, the evidences in favour of the above mentioned regular evolution in time and space are strongly supported by the macroscopic features and depositional environments of these strata.