北山公婆泉斑岩型铜矿床地球化学特征研究

公婆泉铜矿是北山地区最大的铜矿床 ,也是我国西北地区一个非常重要的斑岩型铜矿床。矿体主要产在花岗闪长斑岩和英安斑岩体内。本文对含矿斑岩体、蚀变岩和铜矿石的主元素、稀土元素、微量元素、铅同位素和Sm Nd同位素地球化学特征进行了较为系统的综合分析研究 ,旨在查清含矿斑岩体的形成背景和成岩物质来源 ,以及含矿斑岩体与成矿之间的内在联系。研究结果表明 ,英安斑岩和花岗闪长斑岩体形成于岛弧环境 ,他们具有相同的成岩物质来源 ,是上地幔和下地壳物质混熔产物。花岗闪长斑岩和英安斑岩均具有较高的Cu背景值 ,可为后期Cu的富集提供充足的物质基础。铅和钕同位素数据表明 ,成矿物质以幔源为主 ,主要来自于含矿的斑岩体。

GEOCHEMICAL FEATURES OF THE GONGPOQUAN PORPHYRY COPPER DEPOSIT IN BEISHAN AREA

The Gongpoquan copper deposit is not only the biggest one in the Beishan area, but also a very important copper deposit in northwestern China. The ore bodies in the Gongpoquan deposit are mainly hosted within granodiorite porphyry and dacite porphyry. Based on detailed studies on the major element, rare earth element, trace element, Pb isotope and Sm Nd isotope geochemical features of ore bearing porphyritic intrusives, altered rocks and ore bodies, it is indicated that the granodiorite porphyry and dacite porphyry were formed in the volcanic arc setting were derived from a mixed source of upper mantle and lower crust. It is suggested that the ore forming materials were mainly derived from these porphyritic intrusives, which are high in Cu content. Therefore, the ore forming process of the Gongpoquan deposit is closely related to these porphyritic intrusives.