| 新疆准噶尔北塔山地区晚石炭世侵入岩地球化学特征及构造环境 |
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| 引用本文： | 李高杰,潘硕,侯宇.新疆准噶尔北塔山地区晚石炭世侵入岩地球化学特征及构造环境[J].地质科技通报,2015,34(5):46. |
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| 作者姓名： | 李高杰 潘硕 侯宇 |
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| 作者单位： | 1. 成都理工大学沉积地质研究院, 成都 610059; |
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| 基金项目： | 中国地质调查局项目“内蒙古臭水池等四幅1∶5万区域地质矿产调查项目”(12120114064701) |
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| 摘 要： | 新疆北塔山地区作为中亚造山带的重要组成部分,由于其独特的地理位置,故可以作为研究准噶尔地区构造演化的理想场所。北塔山地区晚石炭世侵入岩类型复杂,早期岩体多为闪长岩类,后期岩体以花岗岩为主,是原始岩浆不同时期演化形成的一套岩石序列,且岩浆具有明显壳幔混合源的特征。在地球化学特征上,里特曼指数σ<3.3、A/CNK<1.1、w(P2O5)<0.65%、Fe2O3/FeO>0.4,岩石相对富集LILE和亏损HFSE,均表现典型Ⅰ型花岗岩类的特征。然而进一步研究显示,晚期侵入体富硅富碱,高钾、低钙铁镁含量的特点指示其为碱性花岗岩的性质,表明北塔山地区在晚石炭世末期经历了由挤压碰撞向后碰撞伸展环境的转变,且转换时限为(290.4±3.2)Ma或更早。所获认识为进一步探讨准噶尔地区及中亚造山带构造环境的演化提供了依据。
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| 关 键 词： | 北塔山 岩石序列 碱性花岗岩 构造环境 后碰撞 |
| 收稿时间： | 2014-10-27 |
Geochemical Characteristics and Tectonic Settings of Late Carboniferous Intrusive Rocks from North Tarshan Area in Junggar,Xinjiang |
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| Affiliation: | 1. Institute of Sedimentary Geology, Chengdu University of Technology, Chengdu 610059, China;2. Hebei Institute of Geological Survey, Shijiazhuang 050081, China |
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| Abstract: | As an important part of the Central Asian Orogenic Belt,the North Tarshan area in Xinjiang provides an ideal place for studying the tectonic evolution of the Junggar region because of its distinctive location.The Late Carboniferous intrusive rocks in the area consist of a complex series of rock sequence showing distinctive features of crust-mantle hybrid,with the early stage rock body dominated by diorites and the late stage rock body predominated by granitoids.This set of rock sequence is produced by the evolution of primitive magma in different stages.All geochemical characteristics,along with Rittman index σ<3.3,A/CNK<1.1,P2O5<0.65%,Fe2O3/FeO>0.4,enrichment in LILE and depletion in HFSE,are typical of I-type granitoids.However,further studies show the late plutons characterized by the rich silicon and alkaline,high potassium,low CaO,FeO,MgO,are alkaline granites,indicating the area has finished environmental evolution from the extruding collision to the post-collisional setting at the end of late Carboniferous and should be formed in a period about or ahead of(290.4±3.2)Ma.The findings will supply crucial evidences to explore the tectonic setting cycle of the Junggar region and the Central Asian Orogenic Belt. |
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