| 中国东南部花岗岩成因与地壳演化 |
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| 引用本文： | 王德滋,沈渭洲.中国东南部花岗岩成因与地壳演化[J].地学前缘,2003,10(3):209-220. |
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| 作者姓名： | 王德滋 沈渭洲 |
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| 作者单位： | 南京大学,内生金属矿床成矿机制研究国家重点实验室,南京大学,地球科学系,江苏,南京,210093 |
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| 基金项目： | 国家自然科学基金资助项目 (4 0 2 72 0 3 6 ,40 13 2 0 10 ) |
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| 摘 要： | 中国东南部不同时代花岗岩类的分布十分广泛 ,各类花岗岩的出露面积达 2 0 0 0 0 0km2 以上。其中 ,前侏罗纪花岗岩大部分具有较低的ε(Nd ,t)、较高的Ni(87Sr) /Ni(86Sr)和较古老的Nd模式年龄 ,相似于周围的前寒武纪基底变质岩。因此 ,它们的主体属壳源型 ,其成因可能主要同华夏地块与扬子地块之间的多次碰撞拼贴有关 ,由当时被加厚的地壳在降压条件下部分熔融形成。燕山期花岗岩在中国东南部分布最广。其中 ,呈东西向展布的燕山早期花岗岩 (南岭花岗岩 )被认为是与印支运动有联系的后造山花岗岩组合 ,多数具壳源型特征。而主要分布于东南沿海的燕山晚期花岗岩则不同 ,它们具有较高的ε(Nd ,t)、较低的Ni(87Sr) /Ni(86Sr)和相对年轻的Nd模式年龄 ,反映其源区中含有较多的地幔组分。它们的形成可能同太平洋板块俯冲、玄武岩浆底侵以及由此引起的地壳深熔和壳幔混合有关。根据花岗岩的Nd模式年龄以及地壳岩石中继承锆石U Pb年龄 ,认为中国东南部地壳具幕式生长特征 ,古—中元古代为主要的生长期。
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| 关 键 词： | 花岗岩 Nd同位素 地壳演化 中国东南部 |
| 文章编号： | 1005-2321(2003)03-0209-12 |
| 修稿时间： | 2003年2月16日 |
GENESIS OF GRANITOIDS AND CRUSTAL EVOLUTION IN SOUTHEAST CHINA |
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| WANG De-zi,SHEN Wei-zhou.GENESIS OF GRANITOIDS AND CRUSTAL EVOLUTION IN SOUTHEAST CHINA[J].Earth Science Frontiers,2003,10(3):209-220. |
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| Authors: | WANG De-zi SHEN Wei-zhou |
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| Abstract: | Granitic rocks of different periods are widespread in Southeast China. Various types of granitoids crop out extensively over 200 000 km~2 in the area. Most of pre-Jurassic granitoids in this region exhibit lower ε(Nd, t),higher N_i(~(87)Sr)/N_i(~(86)Sr) and older Nd model ages, which are very similar to those of surrounding Precambrian metamorphic basement rocks. Genetically, these granitic rocks are mostly crust-derived and may have been related to multiple collision events between Cathaysia and Yangtze blocks. They are the products of partially melting of thickened continental crust under the depressurized condition. Yanshanian granites are the most widespread ones in Southeast China. Among them, the early Yanshanian granites (Nanling granites) arranged in E-W direction are believed to be post-orogenic granite assemblage related to Indosinian movement. They are mainly crust-derived granitoids. However, the late Yanshanian granites in southeast coastal area show rather different features. They often exhibit higher ε(Nd, t),lower N_i(~(87)Sr)/N_i(~(86)Sr) and relatively younger Nd model ages, suggesting that more mantle components have been put in the petrogenetic processes. Their formation may have been closely related to the subduction of Pacific Plate as well as the underplating of contemporary basaltic magma, which led to the anatexis of basement rocks of continental crust and strong crust-mantle mixing. According to the Nd model ages of granites and the U-Pb ages of inherited zircons in crustal rocks, it is concluded that the Southeast China continental crust experienced episodic growth. The Paleo-to Mid-Proterozoic era may have been its main growth time. |
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| Keywords: | granite Nd isotope crustal evolution southeast China |
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