| 中天山地块尾亚地区早古生代构造格架——来自野外地质和锆石U-Pb年代学的证据 |
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| 引用本文： | 周海,陈亮,孙勇.中天山地块尾亚地区早古生代构造格架——来自野外地质和锆石U-Pb年代学的证据[J].地质通报,2017,36(9):1569-1582. |
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| 作者姓名： | 周海 陈亮 孙勇 |
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| 作者单位： | 1. 陕西省宝玉石教学示范中心/陕西国际商贸学院珠宝学院, 陕西 西安 710264;2. 大陆动力学国家重点实验室/西北大学地质学系, 陕西 西安 710069 |
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| 基金项目： | 中国地质调查局项目《北山-东天山及邻区前寒武纪陆块组成及对比》（编号：1212011121137）和国家自然科学基金项目《固阳花岗-绿岩地体的成因及晚太古代地壳生长机制》（批准号：40602023）、《鱼洞子杂岩的成因与扬子克拉通晚太古代地壳增生》（批准号：41072147） |
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| 摘 要： | 野外地质调查发现尾亚地区分布的主体为岛弧杂岩,被更晚的造山后花岗岩如钾长花岗岩等侵入改造。尾亚地区的岛弧杂岩受造山作用的改造,局部发生了一定程度的变质变形作用。这套变质岩分布局限,变质程度较低且主要为绿片岩相,劈理化强。2个样品YM01、YM02分别为黑云斜长变粒岩、角闪斜长变粒岩,其原岩分别为中酸性火山碎屑岩及闪长岩。2个样品的锆石年龄记录了中天山地块北侧的岛弧岩浆事件,表明古亚洲洋(北天山洋)从奥陶纪已经开始,一直持续到泥盆纪由北向南持续俯冲。俯冲过程在晚寒武世开始,暗示中天山地块北侧在当时已经发生了构造转换,作为一个微陆块由被动大陆边缘转变为主动大陆边缘。另外,岛弧杂岩体中没有前寒武纪年龄记录的特征,表明区域内的前寒武纪基底物质分布有限,而变质变形强烈的部分多为造山过程的产物,是在造山带后期改造形成的。
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| 关 键 词： | 中天山地块 岛弧岩浆增生作用 奥陶纪-泥盆纪 尾亚地区 |
| 修稿时间： | 2017/2/6 0:00:00 |
The Early Paleozoic tectonic framework in Weiya area of Central Tianshan Block-Evidence from field geological investigation and zircon U-Pb chronology |
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| ZHOU Hai,CHEN Liang and SUN Yong.The Early Paleozoic tectonic framework in Weiya area of Central Tianshan Block-Evidence from field geological investigation and zircon U-Pb chronology[J].Geologcal Bulletin OF China,2017,36(9):1569-1582. |
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| Authors: | ZHOU Hai CHEN Liang and SUN Yong |
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| Institution: | 1. Department of Jewelry, Shaanxi Institute of International Trade and Commerce, Xi''an 712046, Shaanxi, China;2. State Key Laboratory of Continental Dynamics, Department of Geology, Northwest University, Xi''an, 710069, Shaanxi, China |
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| Abstract: | Through detailed field work in Weiya area, the authors hold that the main rock assemblage there consists of arc complexes including some metamorphic rocks intruded by post-tectonic granites such as K-feldspar granite. Moreover, these arc complexes were partly metamorphosed and deformed due to the CAOB orogenesis there. Thus, the distribution of metamorphic rocks is limit-ed, and their metamorphic degree has reached greenschist facies with strong cleavage. Sample YM01, YM02 are respectively biotite plagioclase leptynite and amphibolite plagioclase leptynite, and their original rocks are acidic volcanoclastic rocks and diorite, respec-tively. Both zircons of these two samples have recorded the arc magmatic events in northern Central Tianshan Block, suggesting large-scale southward subduction of Tianshan Ocean (part of Paleo-Asian Ocean) between the Ordovician and Devonian. The earli-est subductive processes of Tianshan Ocean from the Late Cambrian indicate that the tectonic transformation occurred in Central Tianshan Block from passive continental margin to active continental margin at that time. Moreover, there are no Precambrian age re-cord in arc complex there. Combined with previous work, the authors hold that at least in Weiya area there must have existed limited Precambrian materials and metamorphic rocks with strong foliations and cleavages, which were probably connected with the orogenic tectonics. |
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| Keywords: | Central Tianshan Block arc magmatic accretionary process Ordovician to Devonian Weiya area |
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