东准噶尔晚古生代次火山侵入岩锆石SHRIMPU-Pb年龄及Sr-Nd同位素地球化学  

Zircon SHRIMP U-Pb Dating and Sr-Nd Isotopic Geochemistry of Late Paleozoic Subvolcanic-Intrusive Rocks in Eastern Junggar

作　　者：张峰[1,2] 徐涛[2] 郭晓东[2] 范俊杰[2] 张栋[2] 潘爱军[2] 朝银银[2] 

机构地区：[1]中国地质大学,北京100083 [2]中国人民武装警察部队黄金地质研究所,河北廊坊065000

出　　处：《新疆地质》2014年第1期6-13,共8页Xinjiang Geology

基　　金：国土资源部地质矿产调查评价项目(1212011085018)资助

摘　　要：东准噶尔地区石炭纪巴塔玛依内山组火山岩-次火山侵入岩发育.本文以卡拉麦里构造带东南部松喀尔苏地区次火山侵入岩-花岗闪长斑岩为研究对象,通过岩石学、SHRIMP 锆石U-Pb 和Sr-Nd 同位素方面的研究发现,所有锆石都具岩浆成因,锆石U-Pb 年龄可分为多组,其中最小的-组年龄为305.5~316.3 Ma,代表岩体的形成时间,其他年龄多与准噶尔地区产出的具洋壳和岛弧性质的岩浆岩时代-致.岩石具正的εN（d t）（3.0~15.1）,中等的87Sr/^86Sr 初始值（0.703 861-0.713 151）,较小的T2DM（412-839）.反映了东准噶尔地区基底可能由底侵幔源物质和奠基于有限前寒武纪结晶基底之上的古生代残余洋壳、岛弧体系组成,花岗闪长斑岩是新生地壳物质和少量幔源岩浆共同作用的产物,其形成可能与晚古生代古亚洲洋持续的向哈萨克斯坦-准噶尔板块俯冲消减诱发卡拉麦里地区弧后扩张有关.Late Paleozoicvolcanic-subvolcanic-intrusive rocks in Eastern Junggar are developed.Songkaersu granodiorite porphyry,as a part of them,formed in the southeast Kalamali tectonic belt.Petrography,SHRIMP zircon U-Pb and Sr-Nd isotope indicate that all zircons selected are magmatic, and the zircons U-Pb concordant ages of two samples may be sub-divided into many groups,of which the youngest concordant age is 305.5~316.3Ma which can be interpreted as the for-mation age of Songkaersu granodiorite porphyry.On the other hand,others ages such as early Cambrian to early Carbonif-erou are consistent with the ages of oceanic-crust and island-arc magmatic rocks around the Junggar Basin.Moreover,the positiveεNd(t)(3.0 to 15.1), medium 87Sr/86Sr initial ratios (0.703 861 to 0.713 151), and smaller T2DM (412 to 839) may imply that the eastern basement of the Junggar Basin was tectonically amalgamated by underplating of mantle-derived substances and different Paleozoic remnant oceanic crust and arc complexes upon the minor Precambrian continental crust . Songkaersu granodiorite porphyry may result from the interaction of a amount of new-born lower crust and minor asthenospheric mantle or depleted lithospheric mantle,and the formation mechanism of them perhaps might be related to the subduction of the Paleo-Asian oceanic plate under the Kazakhstan-Junggar plate and result in back-arc spreading.

关 键 词：东准噶尔 晚古生代 花岗闪长斑岩 锆石SHRIMPU-PB年龄 SM-ND同位素 

分 类 号：P597.3[天文地球—地球化学]