江西相山火山—侵入杂岩及其包体希土元素地球化学

本文综合性地报道了江西相山中生代中、酸性火山－侵入杂岩的稀土元素地球化学研究，以探讨基底变质岩、火山岩、次火山岩及闪长质包体之间的成因联系和差异性。认为此套火山－侵入杂岩具同源演化关系，推测它们均来源于前震旦系结晶基底，成因上属于陆壳重熔型。这与前人对此研究的主流观点是一致的，同时更具有完整性和系统性。

REE-Geochemistry of Mesozoic Volcanic-Intrusive Complex and Dark Inclusions in Xiangshan District,Jiangxi Pronvince

The dark-coloured enclaves were found in subvocanic dike for the first time in the Xiangshan district,Jiangxi Province,which provi des anew information for studying Mesozoic vocanic-intrusiv e complex in this region.This kind of enclaves exs it in small amounts,with chilled margin,back veins,and other obvious quenchi ng characteristics.Petrologically they are mainly dioritoids. 　　We collected 14 samples,including the basemental rocks，vocanic rocks，subvocan ic rocks and dark enclaves,and made detailed REE analyses on them.Combining wit h the previous study,we tried to explain the genetic relationsh ip and difference between them ina more integrated and systematic way.The data and diagrams demonstrate that: 1) as a whole,the magmas which formed various v olcanic rocks with slight to intermediate fractionation degree of REE and stron g europium negative anomalies,were differentiated and evolved in the same magmatic reservoir.The latter was originated f rom the continental crust; 2) products of the bicyclic volcanic act ivity,rhyodacite and porphyroclast lava,represent double emptying of magma res e rvoir; 3) REE data of dioritic enclaves don't show strong europium negative an omalies.Conseguently we concluded that the the magma of these enclaves was d er ived from a deeper level,and could be a mixture of lower crust and enriched mantle with a higher mixing proportion. 　　Furthermore,Pb,Sr,Nd isotope data also provided similar information.εNd(t) of volcanics and subvocanics are -8.8 and -11.2,respectively,which are very c lose to the upper crust value in southeast China,while that for the dioritic enclaves is -6.5,whichindicates involvement of a deeper source component. 　　Mesozoic vocanic-intrusive complex in Xianshan district was generat ed by the pa rtial melting of sialic lithosphere and belongs to the S-type in origin,whi ch is consistent with the popular point of view.However,discovery of diorit ic enclaves implies possible participation of lower crust oreven upper mantle component.