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分布于华北地台南缘,霍邱一固始交界安阳山地区的八公山群,由一套碎屑岩和碳酸盐岩组成。最近,人们在碳酸盐岩中发现蜒、珊瑚等化石,确定灰岩时代为晚石炭世。但是,碎屑岩的地质时代仍然没有定论。碎屑岩由粉砂质泥岩、石英砂岩、粉砂岩等组成,厚度大于780m。石英砂岩为中.厚层状,中细粒结构,成分成熟度和结构成熟度高,石英含量高达95%以上,属于滨海一陆棚沉积。应用LA-ICP-MS对石英砂岩中碎屑锆石U-Pb年代学研究表明,样品HQ2106和HQ2204最年轻的碎屑锆石U-Pb年龄分别为860±22.2Ma(YSG),877±22.6Ma(YSG),前者代表了地层的最大沉积年龄,它们也得到锆石年龄加权平均值(YC1σ和YC2σ)的支持。因此,研究区八公山群碎屑岩地层时代属于青白口纪(拉伸纪)。该研究结果将为华北地台南缘前寒武纪地层划分对比以及构造演化历史重塑提供重要依据。
Distributed in the southern edge of North China platform, Huoqiu a Gushan junction Gushan Mountain Gushan area, by a set of clastic rocks and carbonate rocks. Recently, fossils such as serpentine and coral were found in carbonate rocks and the limestone age was determined to be Late Carboniferous. However, the geologic age of clastic rock is still inconclusive. Clastic rock by the silty mudstone, quartz sandstone, siltstone and other components, the thickness of more than 780m. Quartz sandstones are medium-thick, thick-grained and medium-grained structures with high maturity and high structural maturity. Quartz sand is over 95% quartz and belongs to the continental shelf. U-Pb dating of detrital zircons in quartz sandstone using LA-ICP-MS shows that the youngest detrital zircon U-Pb ages of samples HQ2106 and HQ2204 are 860 ± 22.2Ma (YSG) and 877 ± 22.6 Ma (YSG), the former represents the maximum sedimentary age of the strata and they are also supported by a weighted average of zircon ages (YC1σ and YC2σ). Therefore, the epoch of the clastic rock in the Bgongshan group belongs to Qingbaikouji (Tensile Age). The results of this study will provide an important basis for the division of Precambrian stratigraphy and the remodeling of tectonic evolution in the southern margin of North China.