| 彭俊,袁杨森,司建涛,孙进,梁永安,楚明春.坦桑尼亚维多利亚湖绿岩带变质火山岩地球化学特征及成岩机制[J].矿产勘查,2018,9(3):485-494 |
| 坦桑尼亚维多利亚湖绿岩带变质火山岩地球化学特征及成岩机制 |
| Geochemical characteristics and petrogenesis of the metavolcanics rocks in Victoria Lake greenstone belt,Tanzania |
| 投稿时间：2017-09-01 |
| DOI： |
| 中文关键词: 坦桑尼亚 绿岩带 地球化学特征 成岩机制 |
| 英文关键词: Tanzania,greenstone belt,geochemical characteristics,diagenetic mechanism |
| 基金项目:国外矿产资源风险勘查专项(编号:201210B01600234)资助。 |
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| 中文摘要: |
| 坦桑尼亚维多利亚湖绿岩带位于坦桑尼亚太古宙克拉通西北部,是重要的金成矿带。火山岩类型主要为变质镁铁质火山岩和变质长英质火山岩,具有双峰式火山岩特征。文章通过对维多利亚湖地区变质火山岩主量元素、微量元素及稀土元素的研究,了解了坦桑尼亚绿岩带构造演化环境和成岩机制。岩石地球化学特征表明:变质镁铁质火山岩属于钙性岩系列,源岩为亏损洋脊玄武岩幔源(DMM)物质和俯冲消减物质(SDC)的混合物；变质长英质火山岩呈高Na2O/K2O比值和高Al2O3含量,强烈的负Nb异常,重稀土元素含量低(Yb为0.24×10-6～0.68×10-6)并有较强的分异作用,这些特征与典型的太古宙TTG岩套相似。该区熔岩具有洋中脊玄武岩和岛弧玄武岩地球化学亲和性特征,具有聚敛边缘构造背景,形成于太古宙弧后盆地。 |
| 英文摘要: |
| The Victoria Lake greenstone belt in NW Archacan craton in Tanzania is an important gold-forming belt. The volcanic rocks mainly consist of metamorphic mafic volcanic rocks and felsic rocks,showing the characteristics of bimodal volcanic rocks.This paper presents a study of the volcanics from the Victoria Lake area on its major and trace elements to further understand the tectonic evolution.Petrogeochemical characteristics show that metamorphic mafic volcanic rocks represent a calcic rock series,which are a result of the interaction between DDM and SDC sources；metamorphic felsic rocks are characteristed by high Na2O/K2O ratios and Al2O3,large negative Nb anomalies and low HREE contents leading to highly fractionated REE patterns.These characteristics are similar to typical of Archaean TGG suits﹒The lavas in this area show the mixture of MORB and arc-like geochemical affinities,presenting a convergent margin tectonic setting,which are formed in an Archaean back arc basin. |
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