甘肃文县秧田坝岩组的重新厘定及其地质意义  

Redefinition of the Yangtianba Formation-complex, Wenxian, Gansu and its geological significanceo

作　　者：苏春乾[1,2] 李勇[1,2] 刘继庆[1] 王瑶培[1] 崔建军[1] 张忠义[1] 

机构地区：[1]长安大学地球科学与国土资源学院 [2]国土资源部成矿作用及其动力学开放研究实验室,陕西西安710054

出　　处：《地质通报》2005年第5期429-437,共9页Geological Bulletin of China

基　　金：中国地质调查局区域地质调查项目(190910200105);国土资源部成矿作用及其动力学开放研究实验室项目资助

摘　　要：碧口群自建群以来经历了多次解体。但解体的地层单元大都分布在东部略阳附近,它们向西如何延伸、区域上怎么对比还不十分清楚。通过1∶5万区域地质调查,认为碧口群的主要组成单元之一秧田坝岩组仍然需要再解体。在原秧田坝岩组分布区域的不同地质体中获得了376Ma±40Ma的Rb-Sr全岩同位素年龄值、珊瑚化石和大量微古植物化石资料。结合岩石组合特征、变质作用-变形作用的差异、区域分布和接触关系,进一步将原秧田坝岩组解体,并填绘出了新的秧田坝岩组、晚古生代构造地层块体:草河坝组、赵家嘴碎屑岩和寒武纪构造地层块体。这说明原秧田坝岩组为非史密斯地层组合,其中包含有不同时代的地层单元,并进一步证实了碧口地体的构造成因。Since the Bikou Group has been set up, it has gone through disintegration many times. However, the disintegrated stratigraphic units are distributed mainly near Lueyang in the east of the West Qinling and it is not yet very clear about how they extend westward and how they correlate with other regional stratigraphic units. 1∶50000 regional geological surveys indicate that the Yangtianba Formation-complex-one of the main component units of the Bikou Group-should be disintegrated again. A whole-rock Rb-Sr age of 376±40 Ma, coral fossils and a wealth of microfloras have been obtained from different geological bodies in the area of the original Yangtianba Formation-complex. On that basis, combined with the differences in rock association, metamorphism and deformation, regional distribution and contact relationships, the original Yangtianba Formation-complex is further disintegrated and the new Yangtianba Formation-complex and Late Paleozoic structural stratigraphic blocks (Caoheba Formation, Zhaojiazui clastic rocks and Cambrian stratigraphic block) are mapped. It suggests that the original Yangtianba Formation-complex is a non-Smith stratigraphic unit, including stratigraphic units of different ages. It also proves the structural origin of the Bikou massif.

关 键 词：西秦岭 秧田坝岩组 草河坝组 赵家嘴碎屑岩 构造地层块体 

分 类 号：P534.3[天文地球—古生物学与地层学]