| 新疆富蕴地区中泥盆统阿勒泰组喀腊曼哲火山岩地球化学特征及构造环境研究 |
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| 引用本文： | 张亚峰,蔺新望,郭岐明,吕军利,赵端昌,王星,王旭,党晨,申维娜.新疆富蕴地区中泥盆统阿勒泰组喀腊曼哲火山岩地球化学特征及构造环境研究[J].西北地质,2013(4):66-80. |
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| 作者姓名： | 张亚峰 蔺新望 郭岐明 吕军利 赵端昌 王星 王旭 党晨 申维娜 |
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| 作者单位： | [1]陕西省地质调查中心,陕西西安710016 [2]西安地质矿产勘查开发院,陕西西安710100 |
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| 基金项目： | 中国地质调查局“新疆1：25万可可托海幅、江德勒克幅区调修测”项目（1212011120503） |
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| 摘 要： | 通过野外调研和相关地球化学研究，表明出露于阿尔泰造山带南缘富蕴地区喀腊曼哲一带的中泥盆统阿勒泰组火山岩由玄武岩和流纹岩组成，为一套典型的双峰式火山岩组合。其中，玄武岩多变质为钠长阳起片岩、绿帘透闪片岩等，属拉斑玄武岩系列，低SiO2、K2O，高Ti，稀土配分曲线显示轻稀土略富集的平坦型，无明显Eu异常（SEu=0．92～1．08），富Th、U等，Nb负异常；流纹岩属钙碱性系列，高SiO2，低K2O，为钠质型，稀土配分曲线显示Eu负异（dEu为0．29～0．58）的右倾型，富集Th、U、La、Ce和Hf，亏损Sr、Nb、Ta、Zr、P、Ti。二者地球化学特征存在明显差异，表明酸性火山岩并不是由基性岩浆分离结晶产生，而可能是与基性下地壳经不同程度的部分熔融有关；基性火山岩为经俯冲流体改造的亏损地幔部分熔融的产物。岩石地球化学分析结果虽然显示其兼具洋中脊和岛弧火山岩的地球化学特征，但结合区域地质背景，其可能并不是形成于弧后盆地环境，而是岛弧裂谷的产物，属于成熟岛弧。
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| 关 键 词： | 阿尔泰造山带南缘 阿勒泰组 双峰式火山岩 岛弧裂谷 |
Geochemical Characteristics and Tectonic Environment Studies of Altay Group Volcanic Rocks of Middle Devonian Epoch in Kalamanzhe Area of the Fuyun Region,Xinjiang |
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| ZHANG Ya-feng,LIN Xin-wang,GUO Qi-ming,LUE Jun-li＇,ZHAO Duan-chang,WANG Xing,WANG Xu,DABG Chen,SHEN Wei-na.Geochemical Characteristics and Tectonic Environment Studies of Altay Group Volcanic Rocks of Middle Devonian Epoch in Kalamanzhe Area of the Fuyun Region,Xinjiang[J].Northwestern Geology,2013(4):66-80. |
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| Authors: | ZHANG Ya-feng LIN Xin-wang GUO Qi-ming LUE Jun-li＇ ZHAO Duan-chang WANG Xing WANG Xu DABG Chen SHEN Wei-na |
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| Institution: | 2 (1. Shaanxi Center of Geological Survey, Xilan 710016, Xitan Institute of Geological And Mineral exploration, Xi＇an Shaanxi, China; 710100, Shaanxi, China) |
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| Abstract: | Field survey and geochemical study indicate that volcanic rocks of Aletai Formation, formed during Middle Devonian, outcropped in Fuyun county, Kalamanzhe area at the south margin of Altay Orogenic Belt. It generally consists of basalts and rhyolites, which are typical rock assemblages of bimodal volcanic rocks. Basaltic rocks are usually altered into albite- actinolite schist and epidote-tremolite schist, which belong to tholeiite series with low SiO2, K20 content, and high Ti content. Its REE distribution pattern is lat-type with LREE slightly enriched. Without any obvious Eu anomaly （SEu=0.92-1.08）, basalt is rich in Th and U, with an Nb negative anomaly. In comparison, the rhyolitic rocks belong to the calc-alkaline series with high SiOz and low K20, which are the agpaitic type. The REE distribution pattern goes rightward with an Eu negative anomaly （SEu=0. 29-0. 58）. The MORB-normalized spider diagram shows evident enrichment in Th, U, La, Ce and Hf and loss in Sr, Nb, Ta, Zr, P and Ti. In terms of REE and trace elements characteristics, there are prominent differences between the basalts and rhyolites, showing that the rhyolites may derive from different degrees of partial melt in the mafic lower crust rather than the fractional crystallization of the basic magma. Whereas, the basalts may derive from partial melt of depleted mantle which was altered by subduction fluid. Geochemical researches of the bimodal rocks reveal that the rocks have geochemical features of both OIB and arc-island, but combined with the regional geological setting, kalamanzhe bimodal volcanics are probably the products of island-arc rifts, and belongs to mature island arc instead of the back-arc basin. |
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| Keywords: | south margin of Altay Orogenic Belt Aletai Formation bimodal volcanic rocks island-arc rifts |
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