| 范志伟.内蒙古额济纳旗北山岩群中石英岩岩组形成时代——LA-ICP-MS锆石U-Pb测年的证据[J].地质找矿论丛,2015,30(4):575-581 |
| 内蒙古额济纳旗北山岩群中石英岩岩组形成时代——LA-ICP-MS锆石U-Pb测年的证据 |
| Formation period of quartzite of Beishan group in Ejina banner, Inner Mongolia-LA-ICP-MS zircon U-Pb dating evidence |
| 投稿时间：2015-01-30 |
| DOI：10.6053/j.issn.1001-1412.2015.04.014 |
| 中文关键词: 北山岩群 沉积旋回 LA-ICP-MS 锆石U-Pb测年 中元古代 内蒙古 |
| 英文关键词:Beishan group sedimentary cycle LA-ICP-MS zircon U-Pbdating Middle Proterozoic Era Inner Mongolia |
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| 中文摘要: |
| 文章通过对北山岩群石英岩岩组地质剖面及岩相学分析,认为石英岩岩组至少经历了5次从(长石)石英杂砂岩→石英砂岩的沉积旋回;石英岩组中矿物组合为石英+黑云母+白云母±角闪石,具高绿片岩相-低角闪岩相的区域变质作用特征。对北山岩群石英岩岩组中石英岩进行LA-ICP-MS锆石U-Pb测年,其样品中碎屑锆石CL图像显示锆石颗粒具有核幔结构,核部锆石多具有岩浆环带,w(Th)/w(U)比值绝大多数大于0.1,说明石英岩岩组物源区岩石主要为岩浆岩。北山岩群石英岩组中最小年龄为1 301 Ma,限定了区内北山岩群形成于中元古代;最大年龄值为2 769 Ma,落入新太古代时期的有三组年龄数据,说明区内可能存在太古宙陆壳。 |
| 英文摘要: |
| Analysis of geological section and petrography of quartzite in Beishan group shows that the quartzite includes five (feldspar) quartz greywacke→sandstone sedimentary cycles. The quartz + biotite + muscovite ± hornblende assemblage of the quartzite is of high green schist-low amphibolite-facied regional metamorphism.LA-ICP-MS zircon U-Pb dating age, core-mantle structure and magmatic ring belt at the core from image of the detrital zircon and most of the Th/U ratio > 0.1 reveal its source from magmatic rock area. The minimum age of 1301 Ma limits its formation period to Middle Proterozoic era. The maximum age of 2769 Ma is of the Neoarchean era implying that there might be Archean continental crust in the source area. |
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