粤西连阳岩体南段LA-ICP-MS锆石U-Pb测年、岩石成因及构造环境

连阳岩体位于扬子板块与华夏板块结合带，岩性为粗中粒斑状角闪黑云二长花岗岩和中细粒斑状黑云二长花岗岩。利用LA-ICP-MS锆石U-Pb法，获得其年龄分别为99.4±0.7 Ma和98.7±0.9 Ma，属晚白垩世侵入岩。岩体具有较高εNd（t）值（-4.22~-7.2和-4.78~-7.52）和较低的T2DM值（1.24~1.49 Ga和1.29~1.51 Ga）。岩石学、地球化学和Sm-Nd同位素研究表明，连阳岩体南段的岩石类型可能为I型和A型的过渡类型。幔源岩浆不仅提供了熔融所需的热，同时也为区内花岗岩的形成提供了物质成分。燕山晚期南岭地区花岗岩的形成构造环境与同期华南花岗岩不同，受印支运动后伸展拉张和古太平洋板块俯冲的双重影响，在拉张剪切环境中形成了东西向花岗岩带。

LA-ICP-MS zircon U-Pb dating,rock genesis and tectonic environment of southern Lianyang intrusive body in western Guangdong

Lianyang pluton, located in the border area between Yangtze plate and Cathaysia plate, consists mainly of coarse-medium-grained hornblende biotite monzogranite and medium-fine -grained biotite monzogranite.Zircon U-Pb pluton ages of 99.4±0.7 Ma and 98.7±0.9 Ma suggest Late Cretaceous granites.The granites have high εNd(t) values (-4.22~-7.2 and -4.78~-7.52) and young Nd model age (1.24~1.49 Ga and 1.29~1.51 Ga).In combination with previous data and mineralogical and geochemical analysis as well as Nd isotopes, the authors have reached the conclusion that the pluton is a transitional type granite between Ⅰ-type and A-type.The mantle provided both the rock material and the heat for the formation of magma.The Nanling granite is different from other granite of Yanshanian period.Influenced by extensional environment after Indosinian and subduction of paleo-Pacific plate, the granite was formed in a tectonic setting of shear-extension.