青海那陵郭勒河东晚三叠世侵入岩形成环境及年代学研究

那陵郭勒河东晚三叠世侵入岩是本区众多矽卡岩型铁矿产的成矿母岩,利用Maniar and Piccoli(1989)提出的五组图解判别构造环境方法,判定其为后造山花岗岩类(POG型),与区域资料吻合.利用U-Pb法测年结果,表明其侵位时代在(214.2±1.3)~(225.2±1.2)Ma,是印支晚期岩浆活动的产物.对其进行岩石学成因和侵位时代研究,为东昆仑华力西—印支造山旋回在晚三叠世晚期进入造山带伸展崩塌提供同位素年代制约,并为研究该区矿产成矿地质背景及今后寻找矿产资源提供指导意义.

Study of Environment and Chronology of Late Triassic Intrusive Rocks in East Nalinggele River of Qinghai

The Late Triassic intrusive rocks existing in east Nalinggele river are the mineralizing parent rocks for numerous skarn-type iron ore deposits in the study area. Using five groups of graphic method proposed by Maniar and Piccoli （1989） for discriminating tectonic environment, we conclude that the intrusive rocks are the post-orogenic granitoids （POG type）, which is in good accordance with regional data. The U-Pb test results show that the emplacement age of the intrusive rocks is between 214.2 ± 1.3Ma, and 225.2 ± 1.2Ma and is resulted from the magmatic activity in late Indo-Chinese epoch. The study of petrology, genesis, and emplacement age provides a way for determining the age when the east Kunlun-Hercinian-Indo-Chinese orogenic cycle was in the stretching and collapsing process in late Triassic. In addition, the study is also significant for further studying the geological settings and for mineral resources exploration in this area.