| 孟庆涛.内蒙古北山地区阿民乌素蛇绿岩的年代学、地球化学特征及大地构造意义[J].地质与勘探,2021,57(1):122-135 |
| 内蒙古北山地区阿民乌素蛇绿岩的年代学、地球化学特征及大地构造意义 |
| Chronology, geochemical characteristics and tectonic significance of Aminwusu ophiolite in the Beishan area, Inner Mongolia |
| 投稿时间：2020-03-31 修订日期：2020-08-20 |
| DOI：10.12134/j.dzykt.2021.01.011 |
| 中文关键词: 蛇绿岩 地球化学 弧后扩张 阿民乌素 北山地区 |
| 英文关键词: ophiolite, geochemistry, back- arc expansion, Aminwusu, Beishan Region |
| 基金项目:中国地质调查局大兴安岭成矿带南段地质矿产调查项目《内蒙古 1:5万标山、咸味井、骨头井、化石山幅区域地质矿产调查》(编号: 12120113056000) 资助 |
|
| 摘要点击次数: 1477 |
| 全文下载次数: 703 |
| 中文摘要: |
| 内蒙古北山地区阿民乌素蛇绿岩是芨芨台子－小黄山蛇绿岩带的重要组成部分，主由变质辉长岩和极少强蛇纹石化橄榄岩组成。变质辉长岩LA-ICP-MS锆石U-Pb年龄453±12 Ma，形成于晚奥陶世。强蛇纹石化橄榄岩MgO（36.90%～37.44%）、Ni（1980×10-6～2232×10-6）、Cr（2312×10－6～2506×10－6）含量高，而Al2O3（0.59%～1.41%）、TiO2（0.01%～0.02%）和∑REE（0.85×10-6～3.25×10-6）含量低，具亏损地幔岩特征；变质辉长岩MgO（7.22.20%～11.66%）相对含量高；Al2O3（15.61%～18.79%）、TiO2（0.20%～0.29%）、P2O5（0.01%）、K2O+Na2O（1.36%～2.43%）含量低，且K2O＜Na2O；∑REE（12.32×10-6～17.44×10-6）相对较高，轻稀土弱亏损，Eu正异常明显，具向左缓倾型稀土配分模式，与N-MORB类似；富集Rb、Ba、Sr等大离子亲石元素，亏损Nb、P、Zr等高场强元素，具俯冲消减带（SSZ型）蛇绿岩地球化学特征。综合大地构造位置、区域地质、岩石组合及地球化学特征分析认为：阿民乌素蛇绿岩形成于弧后扩张环境，为早古生代白云山-洗肠井古亚洲洋向北俯冲，引起弧后扩张所致。 |
| 英文摘要: |
| The Amingwusu ophiolite in the Beishan area, Inner Mongolia is an important part of the Jijitaizi-Xiaohuangshan ophiolite mélange belt. This rock consists of metamorphic gabbro and little serpentinized peridotite. LA- ICP- MS zircon U- Pb dating of metamorphic gabbro shows that the metamorphic gabbro formed at 453±12 Ma, i.e., in Late Ordovician. The content of MgO(36.90%~37.44%), Ni (1980×10-6~2232×10-6), and Cr (2312×10-6~2506×10-6) in serpentinized peridotite is relative high, and the content of Al2O3 (0.59%~1.41%), TiO2 (0.01%~ 0.02%) and REE (0.85×10-6~3.25×10-6) is relative low, showing the feature of depleted mantle. The content of MgO (7.22.20%~11.66%) in metamorphic gabbro is relative high, that of TiO2（0.20%~0.29%), P2O5(0.01%), K2O+Na2O (1.36%~2.43%, K2O＜Na2O) is low. It has a relatively high ∑REE (12.32×10-6～17.44×10-6), in which the LREE is weakly depleted with positive Eu anomalies. Chondrite-normalized REE patterns have a left-inclined feature, similar to N-MORB. The primitive mantle normalized trace element patterns are characterized by the enrichment of the LILE (Rb, Ba and Sr) and depletion of the HFSE (Nb, P and Zr), implying features of supra-subduction zone (SSZ) type ophiolite. Combined with the tectonic setting of the ophiolite, field observations, the rock association and the analysis of geochemistry, this work suggested that the Amingwusu ophiolite formed in the tectonic environment of a back- arc expansion, resulting from northward subduction of the Paleo-Asian ocean around Baiyunshan-Xichangjing in Early Paleozoic. |
|
查看全文
查看/发表评论 下载PDF阅读器 |
| 关闭 |
|
|
|
