| 底侵玄武质下地壳的熔融:来自安徽沙溪adakite质富钠石英闪长玢岩的证据 |
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| 引用本文： | 王强,赵振华,熊小林,许继锋.底侵玄武质下地壳的熔融:来自安徽沙溪adakite质富钠石英闪长玢岩的证据[J].地球化学,2001,30(4):353-362. |
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| 作者姓名： | 王强 赵振华 熊小林 许继锋 |
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| 作者单位： | 中国科学院广州地球化学研究所 |
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| 基金项目： | 国家攀登计划预选项目(95预25)，国家重点基础研究发展规划项目(G1999043202) |
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| 摘 要： | 沙溪石英闪长玢岩具有高Al2O3,Sr/Y,La/Yb，低Y，Yb,Sr正异常，Eu弱负异常－正异常，表现出与adakite岩类似的地球化学特征，与庐枞火山盆地双庙组粗面玄武岩的微量元素特征和Nd-Sr同位素组成类似，研究表明：（1）沙溪侵入岩不是由俯冲的洋壳熔融形成，而是由底侵的玄武质下地壳熔融形成，该玄武质下地壳的物质来源与双庙组玄武岩的来源相似，都为富集地幔；（2）燕山晚期，长江中下游地区可能存在玄武质岩浆的底侵作用，地壳发生垂向增生，沙溪地区地壳厚度曾大于40km，但白垩纪至现在，沙溪地区地壳明显减薄；（3）沙溪铜（金）矿床不是与大洋板片俯冲有关的斑岩铜（金）矿床，而可能是与底侵的玄武质下地壳熔融有关的斑岩铜（金）矿床。
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| 关 键 词： | adakite岩 底侵作用 地壳增生 地壳减薄 橄榄安粗岩 钕－锶同位素 安徽 玄武质下地壳 火成岩 |
| 文章编号： | 0379-1726(2001)04-0353-10 |
| 修稿时间： | 2000年6月24日 |
Melting of the underplated basaltic lower crust: Evidence from the Shaxi adakitic sodic quartz diorite-porphyrites, Anhui Province, China |
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| WANG Qiang,ZHAO Zhen-hua,XIONG Xia o-lin,XU Ji-feng.Melting of the underplated basaltic lower crust: Evidence from the Shaxi adakitic sodic quartz diorite-porphyrites, Anhui Province, China[J].Geochimica,2001,30(4):353-362. |
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| Authors: | WANG Qiang ZHAO Zhen-hua XIONG Xia o-lin XU Ji-feng |
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| Abstract: | The Shaxi sodic quartz diorite-porphyrites have the geochemical chara cteristics as adakite,such as high Al 2 O 3 ,Sr,Sr /Y and La /Yb,low Y and Yb,Sr positive anomaly,and Eu weakly negative abnomaly or positive abnormaly;their characteristics o f trace elements and the composition of Nd-Sr isotope are similar to those of the Shuangmiao Formation basalts in Luzong volcanic basin.On the basis of petrology and geochemistry,it is suggested that:(1)Shaxi intrusive rocks were not forme d by the melting of subducted oceanic slab,but by the melting of underplating basaltic lower crust whose source was the enriched mantle,the same source as the Shuangmiao For-mation basalts;(2)in late Yanshanian,basaltic magma u nderplating might take place in the middle and lower reaches of the Changjiang River,the crust then accreted vertically,and the thickness of crust in Shaxi regio n was larger than 40km for a time,but from C retaceous to now,it has become thin;(3)the copper(gold)porphyry deposit of Shaxi was not related to su bducted oceanic slab,but related to the melting of the underplated basaltic lower crust. |
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| Keywords: | adakite underplating crust accretion crust thinning shoshonite Nd-Sr isotope Anhui Province |
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