南澜沧江结合带火山岩岩浆成因——洋脊洋岛与弧岩浆作用的性质

在对滇西南昌宁—孟连带石炭—二叠纪火山岩和南澜沧江带二叠—三叠纪火山岩的微量元素和稀土元素研究的基础上，划分了岩浆作用类型和岩浆演化系列，探讨了岩浆源区成分特点。昌宁—孟连带玄武质岩浆的演化主要受部分熔融和分离结晶作用控制；这些岩浆可以划分为３个岩浆演化系列：（１）稀土曲线平坦型的洋脊型拉斑玄武岩浆演化系列，其岩浆起源于亏损型地幔；（２）稀土曲线中等富集型的准洋脊型拉斑玄武岩浆演化系列，其岩浆起源于过渡型地幔；（３）稀土曲线强烈富集型的洋岛型碱性玄武岩浆演化系列，其岩浆起源于富集型地幔。南澜沧江带弧火山岩的岩浆成因主要受分离结晶作用控制，也可以划分为３个岩浆演化系列：（１）二叠纪低钾拉斑—中钾钙碱性岩浆演化系列；（２）中南段的晚三叠世低钾拉斑—中钾钙碱性岩浆演化系列；（３）北段的晚三叠世钾玄岩—高钾钙碱性岩浆演化系列

MAGMATIC GENESIS OF VOLCANIC ROCKS OF SOUTHERN LANCANGJIANG CONVERGENT MARGIN MAGMATISM ABOUT OCEAN RIDGE, OCEAN ISLAND AND ISLAND ARC

On the basis of researching of trace element and rare earth element of Carbonic Permian volcanic rocks in Changning Menglian zone and of Permian Triassic volcanic rocks in southern Lancangjiang, magmatism types and magma evolutional series are divided and the feature of component of source region is discussed. The evolution of basaltic magma in Changning Menglian zone is mainly controlled by partial fusion and fractional crystallization, and these magma can be divided into three magma series. The first is tholeiitic magma series which is MORB and is level REE pattern; the second is too tholeiitic magma series which is MORB like and is middle enriching REE pattern; the third is alkali basaltic magma series which is OIB and is strong enriched REE pattern. Correspondingly, above three kinds of magma originated from distinctively depleted mantle, or transitional mantle, or enriched mantle. Magmatic genesis of arc volcanic rocks in southern Lancangjiang zone is mainly controlled by fractional crystallization and this magma can be too divided into three magma series. The magma in Permian is low K tholeiitic to middle K calc alkali series. The magma series in Late Triassic of the southern part of southern Lancangjiang is the same as that in Permian. The magma in Late Triassic of northern part of southern Lancangjiang is high K calc alkali shoshonitic series.