熊耳裂陷印支期同位素地质年龄耦合性

The Coupling Character Between Isotopic Geochronology of Indosinian Epoch in Xiong’er Fault Basin

在熊耳裂陷构造环境背景和演化的基础上 ,应用U Pb稀释法精确确定岩浆活动年龄 (印支期 2 0 8.5±6 .2Ma ,燕山期 12 1.6± 3.9Ma) ;熊耳群上部安山岩40 Ar 3 9Ar法坪年龄 2 0 6 .5 5Ma ,等时线年龄 2 0 7.5 2± 2 .5 6Ma ,指示热扰动年龄 ;北岭金矿、陈胡子沟金矿蚀变矿物Sm Nd法内部等时线年龄 186± 2Ma。这些年龄大于燕山期 ,而与印支期相近 ,显示了印支期岩浆活动、热构造事件和有关成矿作用的耦合性。

Based upon the background and evolution of Xionger Fault Basin tectonic setting the magmatic activity ages were accurately dated (for indosinian Epoch 208.5±6.2Ma,Yanshan Epoch 121.6±3.9 Ma)using U-Pb dilution method, the 40Ar- 39Ar plateau age dated for the upper part of Xionger Group yield 206.55 Ma and its isochrone age dated 207.52±2.56 Ma, indicating thermal disturbunce age, the internal isochron of Sm-Nd method dated for alteration minerals of gold deposits in Beiling Gold Mine and Chen Huzigou Gold Mine yield an age 186±2 Ma. All the dating ages are larger than the age of the Yanshan Epoch and are approached to the age of Indosinian Epoch, showing the coupling character of isotopic geochronology between magmatic activities,thermal tectonic events and mineralization.