Five metamorphic intermediate-acid intrusive rock bodies in Proterozoic have been identified in the central Qimantage by the 1:50000 mineral prospect survey. The intermediate-acid intrusive rock bodies located in amphibolite facies the volcanic-sedimentary rocks are gray-pale flesh red two-feldspar gneiss with eye-shaped. The two-feldspar granites are their original rocks. Zircon U-Pb age is of 832±12 Ma on average, which are known the oldest intermediate-acid intrusive magma products. Geochemistry of rocks is as follows: high K2O (4. 92-5. 76 × 10-2), poor FeO, MgO, and CaO. Rocks with high-K are calc-alkaline S-type high-evolution granites that were formed about 34. 7 km in crustal thickness. Tectonic setting is shown sys-collision by R1-R2 discriminant diagrams. Rodinia continent closed at about 830 Ma in the East Kunlun. Intermediate-acid magma action reproduced in early Paleozoic. In this process Rodinia breakup and plates in low latitudes moved to high-latitude. The discovery is important to know the structure evolution of early Paleozoic in East Kunlun.%通过1∶5万矿产远景调查在祁漫塔格中部固定出5个大小不等的元古代中酸性高钾(变质)侵入岩体,岩性为灰-浅肉红色眼球状二长片麻岩,分布在角闪岩相的火山-沉积岩系中,原岩恢复为二长花岗岩类.锆石U-Pb表面年龄加权平均值为832士12 Ma,是区内已知最早-期中酸性岩浆侵入活动的产物.岩石具高K2O(4.92～5.76×10-2),贫FeO、MgO、CaO的特点.岩石为高钾钙碱性S型高演化的花岗岩,形成地壳厚度约34.7 km,反映同碰撞挤压构造背景.研究表明Rodinia大陆在东昆仑地区830 Ma左右碰撞闭合,此后到早古生代中期,中酸性岩浆活动进入了一个相对不活动的时间段,为Rodinia解体时期,也是板块从低纬度向中高纬度漂移的时期.这一发现对认识东昆仑早古生代构造演化具有重要意义.
展开▼
