赣南遂川地区基性岩脉的性质及构造意义

文章以赣南遂川地区的基性岩脉为研究对象,通过野外地质观察和室内岩石学、地球化学以及锆石LA-ICP-MS U-Pb年龄测定分析,并对其岩石学、地球化学特征、形成时间、岩浆成因及构造环境等有关问题进行探讨。基性岩脉测年结果为446 Ma±6.6 Ma—422.3 Ma±7.3 Ma,属加里东晚期区域性伸展环境的产物。主、微量元素分析显示基性岩墙为拉斑碱性系列,属于富钠基性岩类;稀土配分曲线与地幔岩浆型稀土元素曲线模式相似,说明岩浆来源与地幔岩浆有密切关系。赣南存在加里东期的酸性和基性侵入岩,反映了地壳构造环境由早期挤压环境渐变为后期伸展环境的演化过程。

The nature and tectonic significance of basic dykes in Suichuan area, south Jiangxi province

This paper deals with the basic dykes in Suichuan area of the south Jiangxi province.Petrology,geochemical characteristics,formation time,magma genesis and tectonic environment of the dykes are discussed based on field observation and indoor petrological and zircon U-Pb dating analysis.Four samples are dated at 446 Ma±6.6 Ma,431.9 Ma±5.7 Ma,422.3 Ma±7.3 Ma and 426.6 Ma±6.9 Ma showing that the dykes are products of regional tension during the early Paleozoic Silurian late Caledonian period.Analysis of the trace and major elements shows that the mafic dykes fall into the tholeiite series and alkaline series belonging to the sodium-rich basite.Their REE patterns similar to those of mantle magma indicates that source material of the dykes are closely related to mantle rock.The both acid and basic intrusions of Caledonian period occur in the area reflect the crustal tectonic setting evolved from the early compression to the late extension in the area.