| 北祁连中段早古生代双向俯冲——碰撞造山模式剖析 |
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| 引用本文： | 左国朝,吴汉泉.北祁连中段早古生代双向俯冲——碰撞造山模式剖析[J].地球科学进展,1997,12(4):315-323. |
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| 作者姓名： | 左国朝 吴汉泉 |
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| 作者单位： | 甘肃省地矿局研究所(左国朝)，西安地质矿产研究所(吴汉泉) |
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| 摘 要： | 在十余年野外考察的基础上，通过火山－沉积组合，高压变质带及俯冲杂岩带产出特征，花岗岩浆活动，同位素年龄值等综合分析研究，结合近年区调成果，提出北祁连中段地区旱古生代的构造演化模式，认为该区是在古陆壳基底上由震旦纪打开经海底扩张生成的留有微陆块的微洋盆，寒武－奥隐纪，以黑河－八宝河为轴发生海底扩张，同时分别向南北两侧发生了俯冲杂岩带也随之由南向北先后反弹回跳到地表，转化为汇聚过渡壳；南侧由早期被动陆
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| 关 键 词： | 双向俯冲 造山带 造山模式 构造演化 |
A BISUBDUCTION COLLISION OROGENIC MODEL OF EARLY PALEOZOIC IN THE MIDDLE PART OF NORTH QILIAN AREA |
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| ZUO Guochao.A BISUBDUCTION COLLISION OROGENIC MODEL OF EARLY PALEOZOIC IN THE MIDDLE PART OF NORTH QILIAN AREA[J].Advance in Earth Sciences,1997,12(4):315-323. |
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| Authors: | ZUO Guochao |
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| Institution: | Institute of Geoscience,Gansu Bureau of Geologyand Mineral Resources,Lanzhou 730000；Xi'an Institute of Geology and Mineral Resources,Xi'an 710054 |
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| Abstract: | A tectonic evolution model of Early Paleozoic in the middle part of North Qilian Area is put forward based on the field investigation of more than ten years, and a series of comprehensive researches, including volcanic sedimentary association, the characteristics of the complex in high pressure metamorphism zone, subduction complex rock zone, granitic magmatism and isotopic age, etc. In Sinian, paleocontinental crust broke up, and micro ocean basin was formed with remnant fragmants of continental crust. In Cambrian Ordovician, asymmetric bisubduction took place southward and northward respectively with Heihe Babaohe Zone being a spreading ridge. During the northward subduction, progressive back arc extension gave rise to a new ocean crust. This type of events took place northward repeatedly, and their correspondant products, subduction complexes, were elevated back to the surface and transformed into convergent transitional crusts. During the southward subduction, the earlier extentional transition crusts were transformed to Alaska type active continental margins which subducted southward, and subsequently arc back extensional basin was formed . In Silurian, with subduction ended and the oceanic basin disappearing, a tectonic framework with the coexistence of island chains and turbidity trough was formed. In Devonian, an orogenic belt with new continental crust was formed as the result of the convergence and collision between the Alaskan massif and the Middle Qilian massif. |
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| Keywords: | Northern Qilian Area Extentional transition crust Bisubduction Subduction complex rock Convergent transition crust Orogenic belt |
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