基于流体包裹体及稳定同位素的河北平泉下金宝金矿床成矿机理

摘要

下金宝金矿床位于永安—下营房—毛家沟金多金属成矿带.本文作者以河北下金宝金矿床流体包裹体和稳定同位素为研究对象,分析了本区成矿物质来源、成矿流体来源及其演化,进而探讨本矿床的成矿机理.宏观地质特征和S、Pb同位素示踪结果表明,本区成矿物质主要由下金宝花岗质岩浆提供,部分来源于围岩.H、O同位素组成特征显示,本区成矿流体来源于岩浆水.流体包裹体特征表明,本区早阶段的成矿流体在演化过程中发生了沸腾作用,导致金的沉淀,中、晚阶段成矿物质沉淀的主导因素为流体的混合作用,而水/岩反应促使金沉淀的现象贯穿成矿的始终.%The Xiajinbao gold deposit is located in Yong'an—Xiayingfang—Maojiagou polymetallic metallogenic belt, which is an important metallogenic belt in North China block. In this paper, we present a detailed study on fluid inclusions and stable isotopes of the Xiajinbao gold deposit, Hebei Province, China, aiming at discussing the ore source, evolution of ore-forming fluid and ore-forming mechanism of the deposit. The macroscopic geological characteristics, S and Pb isotopic analysis results show that the source of ore-forming materials is mainly from granitic magma, and subordinately from country rocks. H and O isotopic composition features indicate that the ore-forming fluid is mainly derived from magmatic water. Fluid inclusion characteristics show that the ore-forming fluid experienced boiling during the early mineralization stage, which led to the precipitation of gold. Fluid mixing dominated the precipitation of the ore-forming materials during the middle and late stages. The gold precipitation was caused by water/rock reaction throughout the whole ore-forming process.