中文摘要：

江西德兴银山矿床是一个与陆相火山-次火山作用有关的中-浅成热液铜铅锌金银矿床。前人对该矿床岩浆岩的活动时代研究主要集中在中酸性火山岩和次火山岩上,而对矿区内出露的脉状辉绿岩缺乏关注。本文在前人研究的基础上,运用LA-ICP-MS对矿区内脉状辉绿岩进行了锆石U-Pb同位素定年,获得了3组^206Pb/^238U谐和年龄,其年龄值分别为152±10 Ma、346.6±5.3 Ma和426±46 Ma。结合锆石的成因以及野外辉绿岩脉切穿黄铜矿脉的交切关系,将辉绿岩的结晶年龄确定为152±10 Ma,表明其形成于晚侏罗世。而后2个较老的年龄是从围岩捕获的捕虏锆石的结晶年龄,基性岩浆在上升到地表的过程中可能与古生代地壳物质发生混染。辉绿岩的年龄表明银山矿区内不仅存在早、中侏罗世的中酸性岩浆活动,而且有晚侏罗世的基性岩浆活动。该地区在晚侏罗世可能处于局部伸展构造环境。

英文摘要：

Yinshan deposit in Dexing District of Jiangxi Province, China, is a middle-shallow hydrothermal Cu-Pb-Zn-Au-Ag deposit closely related to continental volcanism-subvolcanism. Many studies have been conducted on the ages of felsic-intermediate volcanic-subvolcanic activities, while little attention has been paid to the diabase exposed in this mine. Based on the previous study, zircon LA-ICP-MS U-Pb dating has been conducted on the vein-like diabase in order to get the ages of mafic magmatic activity of the studied area. Results yield three groups of weighted average ^206Pb/^238 U ages, 152±10 Ma, 346.6±5.3 Ma and 426±46 Ma. Consistent with the origin of zircons and the intercalated relationship between ore veins and the diabase, 157.4±1.7 Ma is considered to be the formation age of the diabase, which demonstrates that Late Jurassic mafic magmatism presented beside the felsic-intermediate magmatism in the Early-Middle Jurassic in this area. The other two older ages might be produced by the xenoliths zircons captured from wall rock, and it is possible for the mafic magma to be contaminated by the Paleozoic crust material during ascending. The diabase is likely distributed in stretch environment; therefore, this area might be in a regional stretch tectonic setting in the Late Jurassic.