华北克拉通南缘安沟群的SHRIMP年龄及地层对比

SHRIMP U-Pb ages and stratigraphic correlation of the Angou Group on the southern margin of the North China Craton.

华北克拉通南缘安沟群的时代及地层划分对比一直存有争议。侵吞安沟群的许台花岗岩原划为古元古代,本文通过SHRIMP测试,获得其精确的形成年龄为2503±11Ma。安沟群石梯沟组变质酸性火山岩的SHRIMP锆石U-Pb年龄为2521±11Ma,安沟群寨沟组变质酸性火山岩的SHRIMP锆石U-Pb年龄为2517±12Ma,表明安沟群形成于新太古代,与登封群和五台群的形成时代基本一致。安沟群地层的原岩组合为基性火山岩—中酸性火山岩、泥质-碎屑沉积岩和少量碳酸盐岩,总体上与登封群和五台群的原岩组合类似。

The age, stratigraphic division and correlation of the Angou Group on the southern margin of the North China Craton have been in dispute for a long time. The crystallization age of the Xutai granite which disrupted the Angou Group was once assigned as Paleoproterozoic. In the paper a precise SHRIMP zircon U-Pb age of 2503 +/- 11Ma is obtained for the time. As to the Angou Group themselves, the meta-acid volcanics of the Shitigou Formation and the Zhaigou Formation from the complex give the SHRIMP zircon U-Pb ages of 2521 +/- 11Ma and 2517 +/- 12Ma, respectively. The data show that the Angou Group formed in Neo-Archaean, which is consistent with the formation age of the Dengfeng Group and Wutai Group. In addition, the protolith association of the Angou Group is similar to that of the Dengfeng Group and Wutai Group, too, including the basic and intermediate-acidic volcanics, argillitic to detrital sediments and minor carbonate rocks.