| 张振坤,孙建东,江辉,陆凡,岳继宗,吴守智.新疆博格达造山带西段石炭纪双峰式火山岩地球化学特征及成因[J].地质找矿论丛,2021,36(1):56-66 |
| 新疆博格达造山带西段石炭纪双峰式火山岩地球化学特征及成因 |
| Geochemical characteristics and genesis of the Carboniferous bimodal volcanic rocks in the west Bogda orogenic belt, Xinjiang Autonomous Region |
| 投稿时间：2020-08-31 |
| DOI：10.6053/j.issn.1001-1412.2021.01.007 |
| 中文关键词: 博格达造山带 柳树沟组 双峰式火山岩 大陆裂谷 新疆 |
| 英文关键词:Bogda orogenic belt Liushugou Formation bimodal volcanic rock continental rift Xinjiang Autonomous Region |
| 基金项目:国家重点研发项目（编号：2016YFC0600210）和中国地质调查局项目（编号：DD20190153）联合资助。 |
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| 中文摘要: |
| 新疆博格达造山带博格达峰南侧柳树沟组出露大量双峰式火山岩组合。本文对博格达造山带西段石炭纪双峰式火山岩地球化学特征研究结果表明：①玄武岩具有贫K富Na、富Ti富Al和富Mg的特征，w（K2O）/w（TiO2）、w（K2O）/w（P2O5）值较低且范围较小，总体上玄武岩有轻度的地壳物质混染作用；HREE相对富集，轻重稀土无明显的分馏，玄武质岩浆可能源于亏损地幔部分熔融。②流纹岩富K贫Na，低Ti、Mg；与其共生的玄武岩不同，流纹岩稀土元素含量高于玄武岩，轻重稀土分馏较为明显，为右倾斜率稀土配分模式，Eu的负异常较强（δEu=0.17~0.20），流纹岩可能为地壳物质重熔形成。③博格达造山带西段在晚石炭世时期处于大陆裂谷环境，其形成与古亚洲洋顺着克拉麦里碰撞带斜向对准格尔-吐哈地块发生俯冲紧密相关。 |
| 英文摘要: |
| A large number of bimodal volcanic assemblages occur in the Liushugou Formation on the southern side of the Bogda Peak of the Bogda Orogenic Belt. Basalt is depleted in K and rich in Na, Ti, Al and Mg with lower values of w(K2O)/w(Ti2O) and w(K2O)/w(P2O5) and limited range. Generally the basalt is slightly contaminated by crustal materials with relative HREE enrichment and without HREE and LREE fractionation. The basaltic magma may originate from partial melting of the depleted mantle. Rhyolite is rich in K, but poor in Na, low in Ti, Mg. Differing from the basalt the rhyolite is higher in REE with obvious HREE and LREEE fractionation and a right slope distribution model and stronger negative Eu anomaly (δEu=0.17-0.20). The rhyolite may be formed by the remelting of crustal material. Comprehensive analysis shows that the Bogda area was under continental rift environment in Late Carboniferous Epoch and the rock assemblage is closely related to the subduction of the Paleo-Asian Ocean beneath the Junggar-Taha block along the Clamary collision zone. |
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