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*
投稿时间:2016-12-01  修订日期:2017-02-02  点此下载全文
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杨富全 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 fuquanyang@163.com 
柴凤梅 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  
李强 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  
杨成栋 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  
中文摘要:提要:克兰盆地是新疆阿尔泰重要的VMS型多金属矿集区,矿床赋存于上志留-下泥盆统康布铁堡组火山沉积岩系中,前人认为盆地底部为中-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年龄为489.7±2.5Ma、480.6±1.3Ma和494.9±2.4Ma,3件样品限定这套片岩年龄为481~495Ma,属晚寒武世-早奥陶世地层。通过对比认为克兰盆地底部和外围的这套岩石组合不属于中-上志留统库鲁木提群、震旦纪-中奥陶世喀纳斯群和中寒武-下奥陶统哈巴群,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。
中文关键词:锆石U-Pb年龄  片岩  克兰盆地  阿尔泰  新疆
 
Discovery the Late Cambrian to the Early Ordovician strata in the basement of the Kelan Basin, Altay, Xinjiang: constrains from zircon LA-MC-ICP-MS U–Pb datings
Abstract:The Kelan Basin is an important VMS type polymetallic ore cluster in the Altay Orogenic Belt, Xinjiang. The deposits are hosted by a suite of volcano-sedimentary rocks of the Upper Silurian – Lower Devonian Kangbutiebao Formation. Previous studies have shown that the exposed basement in the area is the Middle – Upper Silurian Kulumiti Group which is 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 periphery of the Kelan Basin yield weighted mean 206Pb/238U 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 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 – Middle Ordovician Kanasi Group, and the Middle Cambrian – Lower Ordovician Habahe Group. This discovery plays a key role in understanding the geological setting and tectonic evolution of the Altay Orogenic Belt.
keywords:Zircon U–Pb dating  schist  Kelan Basin  Altay  Xinjiang
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