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华北克拉通南缘发育一系列碱性岩体,前人曾划出3个碱性岩带,龙王碱性岩位于中带,对该岩体形成的确切时代仍有较大争议。一些学者将该岩体作为晋宁期伸展体制下形成的碱性岩,并认为这期岩浆活动与扬子北缘同时代的裂解型岩浆活动可以对应。作者等进行了TIMS和SHRIMP法锆石U-Pb年代学研究。样品(T26)采自河南省栾川县庙子镇之北的卢氏管村西的钠铁闪石正长花岗岩。TIMS法U-Pb上交点年龄为1637Ma±33Ma,SHRIMP法206Pb/238U和207Pb/206Pb表面年龄平均值分别为1611Ma±19Ma和1625Ma±16Ma,3组年龄在误差范围内一致。我们选择SHRIMP法207Pb/206Pb表面年龄平均值1625Ma±16Ma作为龙王正长花岗岩的形成时代。因此,龙王碱性花岗岩是华北克拉通1.8～1.6Ga裂解过程中最晚期碱性岩浆活动的产物。石童石童石童
A series of alkaline rocks are developed in the southern margin of North China Craton. Three alkaline rocks have been delineated by the predecessors. Longwang alkaline rocks are located in the middle belt and there is still much controversy over the exact times of the formation of this rock mass. Some scholars regard the rock mass as alkaline rock formed under the extensional system of Jinning Period and believe that the magmatic activity in this period corresponds to the contemporaneous cracking type magmatic activity in the northern margin of the Yangtze. The authors conducted zircon U-Pb dating of TIMS and SHRIMP methods. Samples (T26) were collected from the Na-Feizhi granitoid granitoids from the west of Lushi Guan Village in the north of Miaozi Town, Luanchuan County, Henan Province. The average age of 206Pb / 238U and 207Pb / 206Pb in the SHRIMP method was 1611Ma ± 19Ma and 1625Ma ± 16Ma respectively. The age of the three groups was within the error range. We choose SHRIMP 207Pb / 206Pb surface age average of 1625Ma ± 16Ma as the Longwangzhengchang granite formation era. Therefore, the Longwang alkaline granite is the product of the most alkaline alkaline magmatic activity during the 1.8-1.6 Ga pyrolysis of the North China Craton. Shishi Tong Tong Shitong