贺兰山中段古元古代赵池沟岩群的特征

为了研究贺兰山中段元古代赵池沟群的特征，对其低绿片岩相的区域变质岩系进行了变质岩石学、岩石化学特征、微量及稀土元素特征等研究．认为该组岩具有岩石多具变余砂状结构，变质程度较低；上部颜色相对较浅，以浅灰色二长变粒岩为主；上部发育有中基性火山岩；岩石基本未受到构造变形；原岩为沉积岩，下部以中一细粒石英砂岩、石英杂砂岩为主，上部则为中一细粒长石石英砂岩、石英长石砂岩等，含一定碳质成分；沉积构造环境总的说来可能形成于三角洲上部平原环境的特征．可为进一步的相关研究提供理论依据．

The feature of the zhaochigou group complex in the middle of the Helan Mountains in palaeoproterozoic

In order to research the character of Zhaochigou group complex, this set of regional metamorphic rocks with lower tint greenschist facies have been researched by metamorphic petrology, petrology and geochemistry, trace and rare earth elements etc. The group complex has the following characteristics： （l）The rocks often have the blastopsammitic structure and the lower metamorphic grade. （2）The color of upper part of the group complex is relatively shallow, mainly composed of light gray K- feldspar-plagioclase-granulites. （3）The upper part of the group is composed of basic volcanic rocks. （4）The rocks have not been destroyed by tectonic deformation. （5）The original rock are sedimentary rock, the under-part are mainly comprised of medium grain-granule quartz sandstone, quartz miscellaneous sandstone, and the upper-part which with a certain carbonaceous composition, are comprised of medium grain-granule feldspar quartz sandstone and quartzose arkose. （6）Tectonic environment of deposition may be formed in the upper delta plain, and it could provide a theoretical basis for further research.