中文摘要：

宁镇地区安基山岩体最早被厘定为高sr低Y型岩石（Adakite），为深入理解安基山岩体的成因与深部地质作用演化过程，本文利用LA-ICPMS锆石u-Pb定年方法对安基山岩体的花岗闪长斑岩进行了年代学研究，获得其206-Pb／238鹑u加权平均年龄为108．8±1．2Ma，表明岩浆侵位时代为早白垩世。另外，结合本地区高精度年代学数据，构筑了长江中下游地区中生代岩浆岩的精细年代学格架，划分为四个阶段：148～133Ma（第一阶段）、131．127Ma（第二阶段）、126—123Ma（第三阶段）以及109—102Ma（第四阶段）。

英文摘要：

The Anjishan pluton in Ningzhen area（i, e. Nanjing--Zhenjiang area） is the earliest conformed to be adakitic rocks in the Middle and Lower Yangtze Val｜ey. For further understanding its petrogenesis and the deep geological evolution, we did geochronology using zircon LA-ICPMS U-Pb dating for the granodiorite porphyry from Anjishan pluton. A weighted mean 206Pb/235U age of 108.8 ± 1.2 Ma is obtained, which represent magma intrusive age of Early Cretaceous. In addition, the refined geochronological framework of the Mesozoic magmatic rocks in the Middle and Lower Yangtze Valley is established by combining with the expressed high precision data of ages. It can be divided into four stages, namely 148 -133 Ma （the first stage）, 131 -127 Ma （the second stage）, 126 - 123 Ma （the third stage） and 109 - 102 Ma （the fourth stage）.