| 武当地块耀岭河群中两类不同性质的酸性火山岩研究 |
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| 引用本文： | 罗郧,李金发.武当地块耀岭河群中两类不同性质的酸性火山岩研究[J].大地构造与成矿学,2010,34(1). |
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| 作者姓名： | 罗郧 李金发 |
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| 作者单位： | 武汉地质矿产研究所,湖北,武汉,430223;武汉地质矿产研究所,湖北,武汉,430223 |
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| 摘 要： | 耀岭河群火山岩中可划分出两类不同性质的酸性火山岩:酸性岩A主要属碱流岩-白碱流岩类,酸性岩B主要属流纹英安岩/英安岩类。总体上看二者主量元素组成差异不大:SiO2含量为65.00%～79.85%,(Na2O+K2O)为5.26%～9.68%。强烈富集Th、Nb、Ta、La、Ce、Nd、Zr、Sm和Hf等微量元素,强烈亏损Ba、K、Sr、P、Ti等元素,稀土元素特征表现为∑REE很高(339.94～1152.85μg/g),具有强烈的铕负异常(δEu=0.18～0.32),与典型的大陆裂谷流纹岩的稀土曲线一致。酸性火山岩B显示K、Rb、Ba、Th和LREE的正异常和Sr、P、Ti和Nb的负异常,Eu具弱负异常(δEu=0.64～0.88),表现出与酸性火山岩A迥然不同的微量元素及稀土元素特征,而与耀岭河群基性火山岩相似,显示其成因可能与之有相同源区。
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| 关 键 词： | 酸性火山岩 两类 地球化学 耀岭河群 |
Geochemical Characteristics for Two Types of Acid Volcanic Rocks of the Yaolinghe Group in the Wudang Block |
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| LUO Yun,LI Jinfa.Geochemical Characteristics for Two Types of Acid Volcanic Rocks of the Yaolinghe Group in the Wudang Block[J].Geotectonica et Metallogenia,2010,34(1). |
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| Authors: | LUO Yun LI Jinfa |
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| Abstract: | The acid volcanic rocks of the Yaolinghe Group can be divided into two types: A-group and B-group, belonging to pantellerite/comendite and rhyodacite/dacite, respectively. The major elemental characteristics of the two types of rocks are quite similar. Their SiO_2 and (Na_2O+K_2O) contents range from 65.00% to 79.85% and 5.26% to 9.68%, respectively. The A-group acid volcanic rocks are rich in Th, Nb, Ta, La, Ce, Nd, Zr, Sm, Hf and depleted in Ba, K, Sr, P, Ti. They are high in ∑REE(339.94～1152.85μg/g) and show notable Eu negative anomalies (Eu/Eu~*=0.18～0.32) on the REE patterns, which are similar to those of typical rhyolites in the continent rift setting. The B-group acid volcanic rocks have high contents of K, Rb, Ba, Th and LREE, and show negative anomalies of Sr, P, Ti, Nb and slight negative Eu anomalies (Eu/Eu~*=0.64～0.88). The characteristics of rare earth and other trace elements of the B-group rocks are obviously different from those of the A-group rocks, but similar to those of their basic counterparts, suggesting that the B-type volcanic rocks may have a close relationship with the basic volcanic rocks originally. |
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| Keywords: | acid volcanic rock geochemisty Yaolinghe Group |
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