投稿时间：2018-03-29
修订日期：2019-01-25
网络发布日期：2019-07-03
中文摘要:黑龙江省上马场金矿床位于兴安地块东缘白乃庙-多宝山成矿带东部，是区内浅成低温热液型矿床的典型代表，龙江组粗面岩为主要容矿围岩，矿化以石英-碳酸盐脉形式产出。文章通过对矿区龙江组火山岩岩石地球化学分析和LA-ICP-MS锆石U-Pb测年，讨论了火山岩形成的构造环境与成岩成矿时代。岩石地球化学分析结果表明火山岩具有相同的微量元素特征，属于高钾钙碱性-钾玄岩系列，富集轻稀土元素和大离子亲石元素（如Rb、Ba、Th、K），Eu弱负异常，亏损高场强元素（Nb、Ta、Ti）。LA-ICP-MS锆石U-Pb测年结果显示，与成矿关系密切的粗面岩和流纹岩的锆石加权平均年龄分别为（123.4±2.1） Ma和（123±3.7） Ma，为早白垩世火山作用的产物。结合东北地区构造演化特征，认为上马场火山岩属于同源岩浆演化的不同产物，形成于蒙古-鄂霍茨克洋闭合机制下后碰撞伸展背景，正是这种伸展背景为区域大规模岩浆活动提供了足够的能量和空间，以金为代表的金属元素开始大量富集，形成了上马场金矿床。
Abstract:Located in the east part of Bainaimiao-Duobaoshan metallogenic belt on the east margin of Xing'an massif, the Shangmachang gold deposit is a typical representative of epithermal deposits in the metallogenic province. The andesite in the Longjiang Formation is the main host rock. The mineralization is closely related to the quartzcarbonate vein. In this paper, representative samples of volcanic rocks from the deposit in the Longjiang Formation were analyzed for major, trace elements and zircon U-Pb dating to validate its tectonic setting and formation ages. Geochemical data indicate that the volcanic rocks vary from high-K calc-alkaline to shoshonitic series in composition with enrichment of large ion lithophile elements such as Rb, Ba, Th and K, moderate negative Eu anomaly and depletion of high field strength elements such as Nb, Ta and Ti. LA-ICP-MS zircon U-Pb dating shows that ore-related andesite and rhyolite from the Shangmachang gold deposit have weighted average ages of (123.4±2.1)Ma and (123±3.7)Ma, respectively. Combined with the tectonic evolution in Northeast China, it is considered that Shangmachang volcanic rocks belong to different products of the evolution of homologous magma and were formed in a post-collision extension environment, which was related to closure of MongoliaOkhotsk Ocean. It is this extension background that provided enough energy and space for large-scale magmatic activities in this region. Metal elements represented by gold began to be concentrated in large quantities and formed Shangmachang gold deposit.
keywords:geochemistry volcanic rocks zircon U-Pb age Shangmachang gold deposit Heilongjiang Province
文章编号：
中图分类号：P618.31
文献标志码：
基金项目:本文得到中国地质调查局项目（中蒙俄铜镍铀资源潜力评价示范）资助
引用文本：
王凤博,杨言辰.2019.大兴安岭北段上马场金矿床火山岩地球化学特征、锆石U-Pb年龄及地质意义[J].矿床地质,38(3):571~585WANG FengBo,YANG YanChen.2019.Geochemistry, zircon U-Pb ages and geological significance of volcanic rocks from Shangmachang gold deposit, Northern Da Hinggan Mountains[J].Mineral Deposits38(3):571~585
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