| 安徽的地壳演化:Sr,Nd同位素证据 |
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| 引用本文： | 陈江峰,谢智,张巽,周泰禧.安徽的地壳演化:Sr,Nd同位素证据[J].安徽地质,2001,11(2):123-130. |
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| 作者姓名： | 陈江峰 谢智 张巽 周泰禧 |
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| 作者单位： | 中国科学技术大学地球和空间科学系,安徽,合肥,230026 |
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| 摘 要： | 在地壳(幔)演化和板块构遣的框架内，评述了有关安徽南部(扬子地块东部，包括大别遣山带和江南遣山带)的同位素地质年代学和Nd，Sr同位素地球化学示踪研究的成果。该地区出露地表的中元古界溪口群浅变质岩代表皖南的基底，沿江地区和大别山区的基底包舍太古宇或／和古元古界古老岩石。此格局还影响到从震旦纪到古生代沉积岩的物源区，江南深断裂以北的沉积岩中有古老岩石的贡献，而以南的物源主要来自出露的中元古界岩石。扬子陆块南北缘(大别和江南遣山带)的晋宁期演化可能与罗迪尼亚超大陆演化有密切关系，但有关研究开展很少。三叠纪大陆深俯冲和超高压变质作用研究已成为国际地球科学的热点。晚中生代(120-140Ma)本区发生强烈的岩浆活动，并伴有重要矿床的形成。中酸性岩的形成是一种壳幔物质混合的过程。沿江地区陆下地幔具有富集特征，为扬子型岩石圈地幔与软流圈地幔混合的产物。从晚中生代到第四纪，基性岩指示其源区的地球化学性质有随时间变得越来越亏损的趋势。
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| 关 键 词： | Nd，Sr同位素 地壳演化：安徽南部 |
| 文章编号： | 1005-6157(2001)02-0123-08 |
| 修稿时间： | 2001年5月8日 |
CRUSTAL EVOLUTION IN ANHUI: Nd AND Sr ISOTOPIC EVIDENCE |
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| CHEN Jiang feng,XIE Zhi,ZHANG Xun,ZHOU Tai xi.CRUSTAL EVOLUTION IN ANHUI: Nd AND Sr ISOTOPIC EVIDENCE[J].Geology of Anhui,2001,11(2):123-130. |
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| Authors: | CHEN Jiang feng XIE Zhi ZHANG Xun ZHOU Tai xi |
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| Abstract: | Geochronological and Nd and Sr isotopic work on crustal and tectonic evolution of southern Anhui,including the Dabie and Jiangnan orogenic belt,was reviewed in this paper.Mid Proterozoic Shangxi Group low grade metamorphic rocks exposed in the southern margin of the Yangtze block represent the basement of the region.However,the basement of the region along the Yangtze River and the Dabie Mountains contains Archean and /or Paleo Proterozic rocks.The source material for the Sinian to Paleozoic sedimentary rocks was controlled by different basement rocks.Sinian and Paleozoic sedimentary rocks from the north of the Jiangnan deep fault zone contain old rocks from the northern margin of the Yangtze block,while that from the south of the deep fault contain only material from the Mid Proterozoic basement in the southern margin of the Yangtze block.Jinningian evolution of both southern and northern margins of the Yangtze block might be closely related to the Rodinia super continent although relevant work lacks.Triassic deep subduction of the continent,continent continent collision and ultrahigh pressure metamorphism in the Dabie orogenic belt has become one of focuses of the international interest.Extensive magmatism and related mineralization occurred in the region 120 to 140 Ma ago.Late Mesozoic intermediate and acidic igneous rocks were formed by mixing of the crustal and mantle derived materials.The sub continental mantle along the Yangtze River shows enriched geochemical characteristics and the isotopic characters of the Mesozoic mantle of the region can be modeled by mixing between DMM component representing asthenospheric mantle and EM II representing the Yangtze type lithospheric mantle.From the Later Mesozoic to Quaternary,the isotopic compositions of mafic intrusive rocks and basalts show a progressive change toward more depleted mantle characteristics. |
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| Keywords: | Nd and Sr isotopes crustal evolution southern Anhui |
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