香山群时代讨论

DISCUSSION ON THE GEOLOGICAL AGE OF THE XIANGSHAN GROUP IN THE ORDOS BASIN

鄂尔多斯盆地西及西南边缘中、上奥陶统中发育着一套含有滑塌堆积的大陆坡重力流沉积,中统一般称为平凉群。但在宁夏回族自治区的香山至贺兰山南段这套地层中因发现寒武纪化石而改称香山群,笔者认为其化石发现于滑塌堆积的外来体中,因而其时代仍应归奥陶纪。这样就理顺了地层层序并解决了化石上存在的问题。

A pile of continental slope gravity flow sediments with olistostrom developed in the west and the southwest margins of the Ordos Basin within the middle and upper Ordvician systems. The middle Ordovician is generally referred to as the Pingliang Group while it is remained as the Xiangshan Group in Ningxia Hui Autonomous Region due to the discovery of the Cambrian fossils in the sequences. However, the author believes that the geological age of the group should be attributed to the Ordovician Period since the Cambrian fossils discovered in foreign rock fragments. Consequently, the contradiction between the strati-graphic sequence and the discovered fossils can be settlled.