| 秦岭—大别造山带碰撞后中酸性火山岩地球化学特征及构造意义 |
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| 引用本文： | 周文戈,张本仁.秦岭—大别造山带碰撞后中酸性火山岩地球化学特征及构造意义[J].地球化学,1998,27(6):537-548. |
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| 作者姓名： | 周文戈 张本仁 |
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| 作者单位： | [1]中国科学院地球化学研究所深部室 [2]中国地质大学（武汉）地球科学学院 |
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| 摘 要： | 秦岭－大别造山带中，新生代中酸性火山岩的地球化学研究表明，该区中酸性火山岩是由幔源基性岩浆与壳源物质的混合物经过多种过程综合作用形成的。结合野外地质产状和同位素热年代学资料，作者认为研究区中，新生代火山岩产出于拉张的构造环境中。
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| 关 键 词： | 火山岩 地球化学 构造背景 秦岭－大别 造山带 |
GEOCHEMICAL CHARACTERISTICS AND TECTONIC IMPLICATIONS OF POST-COLLISIONAL INTERMEDIATE AND ACID VOLCANIC ROCKS FROM QINLING-DABIE OROGEN |
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| Zhou Wenge, Zhang Benren, Yang Weiran, Zhao Zhidan,Xie Hongsen.GEOCHEMICAL CHARACTERISTICS AND TECTONIC IMPLICATIONS OF POST-COLLISIONAL INTERMEDIATE AND ACID VOLCANIC ROCKS FROM QINLING-DABIE OROGEN[J].Geochimica,1998,27(6):537-548. |
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| Authors: | Zhou Wenge Zhang Benren Yang Weiran Zhao Zhidan Xie Hongsen |
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| Abstract: | A geochemical study, on major, trace and earth elements, of post-collisional intermediate and acid volcanic rocks from the Qinling-Dabie orogen was carried out.SiO2 contents of these volcanic rocks range from 55% to 79%; MgO contents are less than 4%; and Na2O + K2O contents are larger than 6%. Major element oxides versus SiO2 diagram shows an overall negative covariance of Al2O3 and CaO with SiO2. The other oxides are more scattered. In the chondrite-normalized abundance diagram, the acid volcanic rocks have negative slopes with large relative depletions of Nb, P, Ti comparing with the similar compatible elements. As for the intermediate volcanic rocks,no any relative depletion of Nb was found and the relative depletions of P and Ti are smaller than those of the acid volcanic rocks. In the chondrites-normalized REE diagram, trachyandesites, andesites, dacites and trachydacites show parallel patterns and small Eu anomalies. However, rhyolites have irregular patterns and show remarkable Eu anomalies. The origin of the post-collision intermediate and acid volcanic rocks is analyzed based on its geochemical characteristics. Intermediate and acid volcanic rocks in this area were derived from the mixture of the basic magma and crustal material,which experienced multi-proccess evolution. Based on the geochemical characteristics of these volcanic rocks, the thermal chronological data and the geological evidence,the tectonic setting during the formation of these volcanic rocks is constrained. It is believed that during the volcanic eruption, the structural setting in the Qinling-Dabie orogenic belt transferred from compressive to extensive regime. |
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| Keywords: | volcanic rocks geochemistry structural setting Qinling-Dabie orogen |
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