黔中隆起的形成时间及形成机制探讨

Formation Mechanism and Time of Qianzhong Uplift

黔中隆起经历了水下和陆上两个发育阶段;都匀运动是这一发育转变的成因。问题的焦点是水下隆起的开始时间和都匀运动发生的具体时间。根据沉积相研究,受郁南运动控制,黔中隆起在下奥陶统桐梓组沉积期间已具雏形。对贵阳乌当发现的珊瑚化石Plasmoporella、Heliolites、Amsassia等重新厘定后认为黔中隆起大规模露出水面的时间为晚奥陶世五峰组沉积期结束之时,这也是都匀运动发生的时间。都匀运动本身,受到自南而北方向的滇桂—北越地块的挤压和南东—北西方向的加里东造山运动的挤压,因此在黔中及周缘地区形成了以黔中背斜、乌当—二比向斜为代表的东西向构造和以麻江背斜为代表的南北向构造并存的地质现象。

There have been two general viewpoints about the formation of Qiangzhong Uplift. One is that it experienced stages of underwater and land uprisings. The other is that the land uprising was induced by Duyun move ment. This research trends to agree with the former and deems that Duyun movement caused the transformation between the two uprising stages. The focus is when the underwater uprising began and when Duyun movement took place. Embryo Qianzhong Uplift formed during Early Ordovician Tongzi sedimentary stage in control of Yunan movement. By re-dating the coral fossil, such as Plasmoporella, Heliolites and Amsassia, it is affirmed that the time when the Qianzhong Uplift widely came out of sea was at the end of the Later Ordovician Wufeng sedimentation, i.e. it was just the time of Duyun movement. Qiangzhong Uplift was an inheritanted old uplift that was shaped dudng Yunan movement, rose up during Duyun movement and incorporated during Guangxi movement. Compressed by Yunnan-Guizhou-North Vietnam land mass from south to north and Caledonian orogeny from southeast, two types of geological structures survived simutaneously in Qiangzhong Uplift and its surrounding areas. They are respectively the E-W structures represented by Qiangzhong anticline and Wudang-Erbi syncline, and the S-N structure represented by Majiang anticline.