中文摘要：

内蒙古边家大院银多金属矿床位于大兴安岭成矿带南段,是一个成因类型复杂的银多金属矿床.为了精确厘定该矿床的成岩时代,对区内与成矿关系密切的石英斑岩进行了LA-ICP-MS锆石U-Pb定年.结果表明,该斑岩的形成年龄为140±1.2 Ma,为早白垩世岩浆活动的产物.岩石化学研究表明,边家大院石英斑岩的SiO2含量高（75.62％～75.80％）,Al2O3含量较低（13.32％～13.33％）,Alk质量分数较高（8.60％～8.71％）,K2O/Na2O值为4.51～4.77.稀土配分曲线呈右倾轻稀土富集型,铕亏损强烈,δEu值为0.22.富集高场强元素Zr、Hf、Th和大离子亲石元素Rb、K,而亏损P、Ti、Sr、Ba、La.上述特征显示矿区石英斑岩与A1型非造山花岗岩一致,推断岩浆主要来源于地壳,形成于张性环境.结合矿床地质特征及前人在区域上的研究成果,认为燕山期是大兴安岭南段成矿和成岩高峰期之一,矿区石英斑岩形成的构造背景主要与古太平洋板块向西的大规模俯冲所引起的伸展作用有关.

英文摘要：

The Bianjiadayuan silver poly-metallic deposit is located in the southern section of the Daxing,anling metallogenic belt,which is a genetically complex polymetallic deposit.In order to determine the diagenetic age of the deposit,the U-Pb age study using LA-ICP-MS has been conducted on zircons in the quartz porphyry associated with the mineralization.The results show that the age of the quartz porphyry are ca.140 Ma,indicating that the intrusive rocks are productions of the magmatic activities in the Early Cretaceous.The petrological and geochemical studies show that the Bianjiadayuan quartz porphyry are characterized by high SiO2 content（75.62％-75.80％）,high Alk content （8.60％-8.71 ％） and low Al2O3 content （13.32 ％-13.33％）.The chondrite-nomalized REE pattern show LREE enrichments and strong negative Eu anomalies with δEu value of 0.22.The HFSE （high field strength elements）,such as Zr,Hf,Th,and the LILE （lithophile elements）,such as Rb and Th,are both enriched,whereas elements P,Ti,Sr,Ba and La are significantly depleted.These features are similar to the typical A1 within-plate anorogenic granite,indicating that the magma wes derived from the lithospheric mantle and resided in the tensional tectonic setting.Combined with the geological characteristics and the previous researches,the Yanshanian might be considered as a peak period of mineralization.The tectonic setting of the quartz porphyry might be related to extension after the subduction of the paleo Pacific Plate.