北山地区花牛山群的重新厘定--来自火山岩地球化学证据

摘要

The geochemical characteristics and tectonic setting of Huaniushan Group volcanic rocks are undefined, it caused directly that the geological background and prospecting direction of Huaniushan lead and zinc deposit are unde-fined. Based on the previous research, detailed field geological survey and the data of major element, trace element and Rare Earth Elements (REE) of the volcanic rocks, we can discuss its tectonic background and redivide the volcanic rocks of the previous Huaniushan group into two stages. The volcanic rocks of the Jixianian Period is exposed as fragments morphology, which is the host rock of Huaniushan lead-zinc deposit. And the volcano rocks of the Huaniushan Group are really without mineralization, which is formed in an extensional environment of limited oceanic basin. Base on rock association characteristics, tectonic setting and age of the Huaniushan group, we redefined Huaniushan group, and fur-ther pointed out that“Huaniushan type”deposit prospecting is the strata of Jixianian Period rather than the strata of the Ordovician Period, which provide new evidences to prospect the“Huaniushan type”deposit in Beishan area.%花牛山群火山岩地球化学特征及形成构造背景不清，导致花牛山铅锌矿床成矿地质背景及找矿方向不明确。在已有研究成果基础上，通过野外路线地质调查，据主量、微量及稀土元素地球化学等资料探讨其形成构造背景，认为原划花牛山群包含两期火山岩：①以残片形态出露的蓟县纪火山岩，为花牛山铅锌矿赋矿围岩；②形成环境为有限洋盆拉张环境的奥陶纪火山岩及不含矿火山岩。通过花牛山群火山岩岩石组合特征、形成构造背景、时代，重新厘定花牛山群，指出“花牛山式”矿床找矿方向为蓟县系并非奥陶系，为北山地区寻找“花牛山式”矿床提供了新依据。