鄂尔多斯盆地西部“古陆梁”的形成和演化

从鄂尔多斯盆地西缘地区基本地质事实出发,充分汲取前人的有益成果,历史的分析鄂尔多斯盆地西缘构造应力场特点,结合晚三叠世以来鄂尔多斯盆地西缘盆—山转换的沉积响应,合理利用地震资料所揭示的西缘深部的“CT”图像及物源分析等第一手资料,提出“西缘古陆梁”及“银川古隆起”在印支期是不存在的;燕山主期盆地西缘南段可能形成古陆梁,使得六盘山盆地和鄂尔多斯盆地具一定的分割性,但随后在早白垩世又被夷平,鄂尔多斯盆地又和包括六盘山盆地在内的西部白垩纪盆地连通,鄂尔多斯盆地西界真正形成的时间应在喜山晚期,这也是盆地西缘桌子山—贺兰山—六盘山(“南北向古陆梁”)形成的大致时间,它们是印度板块和太平洋板块远距离应力作用的结果。

FORMING AND EVOLUTION OF ANCIENT LAND RISE IN THE WESTERN ORDOS BASIN

The time of ancient land rise in Western Ordos Basin is one of important question in science theory and practice.Based on the basic geologic proof,the achievements that were acquired by former geologists,through analyzing geotectonic evolvement and geodynamics characteristics and linking with analysis of sedimentation,with the latest seismic and other data,thought that "Western ancient land rise" and "Yinchuan ancient rise" were not found and the both the foreland basin and subside center which ever though were south-north in strike not found,either in late Triassic.The western borderline of the basin may rise in Main Yanshanian period and made Liupanshan Basin separated from Ordos Basin.In early Cretaceous,Liupanshan mountains were leveled to the ground and Ordos Basin connect with western Cretaceous basin including Liupanshan basin late.The western borderline of the Ordos Basin which can be seen now were formed in Middle-late Himalayan period.Zuozishan mountains Helanshan mountains-Liupenshan mountains(South North ancient land rise) were formed in Middle-late Himalayan period,too.These geological phenomenon were the result of the stress effect of far distance,which were caused by active of both Ocean plate India and Pacific Ocean plate.