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香山群是一套经历轻微区域变质作用的陆源碎屑岩,夹有少量碳酸盐岩和硅质岩,主要位于河西走廊东部香山地区。迄今为止,前人已经做过大量工作,但是对香山群与该区奥陶纪米钵山组的关系、香山群的时代以及香山群的物源等问题还存在较大争议。笔者对香山群的碎屑锆石做了定年(LA-ICP-MS)工作,通过香山群与米钵山组锆石年龄的对比,发现米钵山组最年轻锆石(451±8)Ma比香山群最年轻锆石(525±3)Ma年轻,且香山群不含米钵山组其他年轻锆石成分,香山群时代应该晚于(525±3)Ma,而早于中奥陶世米钵山组,应属中—晚寒武世。香山群碎屑锆石年龄谱与华夏地块、阿拉善基底、华北西部和北祁连岩浆变质事件年龄差异显著,华夏地块、阿拉善基底、华北西部和北祁连不是香山群物源,而与澳大利亚西南部地区相似,同时根据香山群古水流分析结果,推测澳大利亚西南部可能是香山群的沉积物源。
Xiangshan Group is a metamorphic terrigenous metamorphic terrestrial metamorphic terrane, sandwiched between a small amount of carbonate rocks and cherts, mainly located in the Hexi Corridor Xiangshan region. So far, a great deal of work has been done by our predecessors, but there is still much controversy over the relationship between the Xiangshan Group and the Ordovician Mibo Mountain Group in this area, the age of the Xiangshan Group, and the source of the Xiangshan Group. According to zircon dating of Xiangshan Group and Mobeizhan Formation, the youngest zircon (451 ± 8) Ma It is younger than the youngest zircon of Xiangshan Group (525 ± 3) Ma, and Xiangshan Group does not contain other young zircons from the Mibozhan Formation. The Xiangshan Group era should be later than (525 ± 3) Ma and earlier than the Middle Ordovician Mibo Mountain group, should be in - Late Cambrian. The age distribution of detrital zircons in Xiangshan Group is significantly different from that of the Huaxia block, the Alxa basement, the western North China and the North Qilian magmatic metamorphic event. The Huaxia block, Alxa basement, western North China and North Qilian are not the source of Xiangshan Group, However, similar to the southwest of Australia, at the same time, according to the analysis of Xiangshan Group ancient water flow, it is speculated that the southwest of Australia may be the sediment source of Xiangshan Group.