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 ε_Nd(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.