海州群变火山岩稀土地球化学及其大地构造环境  

THE GEOCHEMISTRY OF RARE EARTH ELE- MENTS OF METAVOLCANIC ROCKS AND THEIR BEARING ON GEOTECTONIC IN THE HAIZHOU GRAUP OF NORTHERN JIANGSU

作　　者：樊金涛 

机构地区：[1]江苏省地质矿产局区域地质调查大队

出　　处：《火山地质与矿产》1991年第3期49-61,共13页Volcanology & Mineral Resources

摘　　要：苏北海州群火山岩分A—岩系和C—岩系。A-岩系具有富轻稀土元素和无明显铕异常的分布型式,来自上地幔的部分熔融;C-岩系具有富轻稀土元素和明显铕负异常的分布型式,是东海群部分熔融的产物。两者构成海州群火山岩的双峰式特征,它与蛇绿岩套火山岩及岛弧火山岩的特征不同,形成于苏胶南古小陆块南缘的裂陷槽环境。The metavolcanic rocks in the Haizhou graup is divided into A-series and C-series. The REE chondrite normalied of patterns A-series show that they belong to high REE patterns of C-series show that they belong to high REE content (68.47 to 232.62 × 10-6); enriched in light REE, LREE/ HREE4.24 to 9.84 ; Eu-normal, δEu o.77 to 1.09. Their magma was derived from partial melting of the upper mantle. The REE content (135.99 to 351.24ppm); enriched in light REE LREE/ HREE 4.25 to 10.13; negative Eu-anomaly. δEu 0.16 to 0.36. They were derived from partial remelting of sialic crust. It is characteristiced by 'bimodal pattern' in chemical compostion, and it differs from volcanic rocks of ophiolite complex and island arc-volcanic rocks, whereas it has the chemical property of volcanic rocks in the intracontinental rift, and so it may be inferred that the tectonic unit in this area belongs to the austral margin of ancient small landmass in the Su-Jiaonan, then gradudally froming taphrogeosyncline by the process of intracontinental rift. The blueschist belts in the Haizhou graup beolongs to the collision-type mctamorphic belts of high piezocrystallization.

关 键 词：火山岩 稀土族 地球化学 大地构造 

分 类 号：P588.14[天文地球—岩石学]