无锡地区玄武质岩石特征  

Characteristics of Cenozoic basalt in Wuxi district

作　　者：陶忠耀 

机构地区：[1]江苏省地矿局第四地质大队,苏州215154

出　　处：《江苏地质》1992年第1期23-26,共4页Jiangsu Geology

摘　　要：江苏新生代玄武岩,主要出露于西部(盱眙—镇江—线以西),东部由于大面积第四系覆盖,所知甚少。笔者等在无锡地区1:5万区调工作中,发现在无锡市东部。The Cenozoic basalt in Wuxi district includes alkali—olivine basalt and nepheli- nite.The petrochemical research indicates that the basalt contains poorer SiO(2)than aver- age SiO(2)content of Eastern China Basalt and that its mafic index is between 0.60 and 0.65.The solidification index value of basalt and subbasalt is less than 30 far away from the solidification index of original mantle magma,but the solidification index value of olivine nephelinite and basanite is between 38 and 43 which is very close to the original mantle magma.Therefore,the alkaline basalt and subbasalt in the district are quite similar, which are resulted from the same magmatic origin and formed in the same time.The differ- ences are thermal dynamic condition,structure space and occurrence.But the olivine nephelinite is different in geochemical characteristics and has close relations in origin.The rock—formingmateriai is most probably from mantle.Alkaline basalt and subbasalt is not di- rectly dirived from crystallization of primary basaltic magma,but formed bya mixing of magma and crust.The basalt in Wuxi is all controlled by NW trending faults or the cross of NW and NE trending faults.The paper considersthat its forming environment is intraplate rift.

关 键 词：玄武岩 橄榄玄武岩 霞石岩 无锡 

分 类 号：P588.145[天文地球—岩石学]