新疆阿尔泰克兰盆地基底发现晚寒武世—早奥陶世地层——来自LA-MC-ICP-MS锆石U-Pb年龄证据  

The Discovery of the Late Cambrian–Early Ordovician Strata in the Basement of the Kelan Basin, Altay, Xinjiang: Constrains from Zircon LA-MC-ICP-MS U-Pb Dating

作　　者：杨富全[1] 柴凤梅 李强[1] 谷高灵[3] 杨成栋[1] 

机构地区：[1]中国地质科学院矿产资源研究所国土资源部成矿作用与资源评价重点实验室,北京100037 [2]新疆大学地质与矿业工程学院新疆中亚造山带大陆动力学与成矿预测实验室,新疆乌鲁木齐830046 [3]新疆维吾尔自治区地质矿产勘查开发局第四地质大队,新疆阿勒泰836500

出　　处：《地球学报》2017年第6期859-871,共13页Acta Geoscientica Sinica

基　　金：新疆阿勒泰地区资源补偿奖励资金项目"新疆阿尔泰山南缘克兰盆地成矿规律研究及资源潜力评价";国土资源部公益性行业科研专项经费项目(编号:201211073)联合资助~~

摘　　要：前人认为新疆阿尔泰克兰盆地底部为中—上志留统库鲁木提群,岩性为片岩、片麻岩、变粒岩和变质砂岩组合,原岩为陆源碎屑岩和火山岩。本次获得克兰盆地底部和外围原"库鲁木提群"矽线石云母片岩、黑云母斜长角闪片岩和斜长角闪片岩LA-MC-ICP-MS锆石U-Pb年龄分别为(489.7±2.5)Ma、(480.6±1.3)Ma和(494.9±2.4)Ma,3件样品限定这套片岩年龄为481~495 Ma,属晚寒武世—早奥陶世地层。通过对比认为这套岩石组合不属于中—上志留统库鲁木提群、震旦纪—早寒武世喀纳斯群和中—上奥陶统哈巴群,很可能是一套新的岩石地层单位,这一发现对探讨阿尔泰地质背景和构造演化具有重要意义。Previous researchers held that the exposed basement in the Kelan Basin, Altay, Xinjiang, is the Middle–Upper Silurian Kulumiti Group composed of schists, gneisses, granulites, and meta-sandstones and derived from terrigenous clastic rocks and volcanic rocks. In this study, LA-MC-ICP-MS U-Pb analyses of zircons from the sillimanite mica schist, biotite plagioclase hornblende schist, and amphibolite schist of the original ＂Kulumiti Group＂ at the base and in the periphery of the Kelan Basin yielded weighted mean 206 Pb/238 U ages of（489.7±2.5） Ma,（480.6±1.3） Ma, and（494.9±2.4） Ma, respectively, which indicate that this suite of schists was formed during 495 to 481 Ma, belonging to the Upper Cambrian–Lower Ordovician strata. This suite of rocks at the base and in the periphery of the Kelan Basin, by contrast, is considered as belonging to a new set of lithostratigraphic units, rather than the Middle–Upper Silurian Kulumiti Group, Sinian–Lower Cambrian Kanasi Group, and the Middle–Upper Ordovician Haba Group. This discovery plays a key role in understanding the geological setting and tectonic evolution of the Altay Orogenic Belt.

关 键 词：锆石U-PB年龄 片岩 晚寒武世—早奥陶世地层 克兰盆地 阿尔泰 

分 类 号：P597.1[天文地球—地球化学] P534.41[天文地球—地质学]