刘芳;宋史刚;丁振举;周宗桂;张振飞;梅燕雄;

• 1:兰州文理学院经济与管理学院
• 2:中国地质大学资源学院
• 3:甘肃省国土资源厅
• 4:中国地质科学院矿产资源研究所

摘要(Abstract)：

对甘肃小柳沟钨钼矿床进行了辉钼矿Re-Os和白云母Ar-Ar同位素定年。2件辉钼矿样品获得的Re-Os模式年龄分别为(427±6)Ma和(428±6)Ma,平均(427.5±6)Ma;3件白云母Ar-Ar定年获得的Ar-Ar坪年龄分别为:(391.98±1.95)、(391.13±1.88)、(392.04±1.98)Ma,平均(391.7±1.9)Ma。上述年龄指示小柳沟钨钼矿化发生在428~392Ma之间。碰撞造山过程中地壳收缩增厚、深部岩石增温加压和变质脱水,特别是在构造体制由挤压向伸展转换阶段的构造减压,将进一步促使部分熔融过程及花岗岩浆的形成。含矿岩体从岩浆源区通过部分熔融作用获取成矿物质,在岩浆后续分异演化过程中,作为不相容元素的W、Mo将倾向于在残余的熔体中进一步富集。随着岩浆上侵到浅部,因温度、压力的下降而使含水流体或挥发分饱和而发生出溶,成矿元素将优先进入溶液,并随溶液迁移到赋矿的断裂或裂隙中沉淀成矿。因此,碰撞造山过程为祁连造山带同期含矿岩体的形成和钨钼成矿提供了有利的动力学环境,而花岗岩浆上侵、结晶分异和流体析出,为W、Mo元素的最终迁移、富集成矿提供了热动力学条件。因为造山后伸展阶段更利于花岗岩浆上侵和流体的分异,所以此阶段形成的花岗岩与成矿关系更为密切。因此,祁连地区钨钼的进一步找矿工作,应对造山阶段尤其是造山作用后伸展阶段花岗岩给予高度重视。

关键词(KeyWords)： Re-Os;Ar-Ar;同位素定年;钨钼矿床;花岗岩;小柳沟;北祁连

Abstract:

Keywords:

基金项目(Foundation): 甘肃省矿产资源专项“祁连西段多金属矿床预测研究”(2008026095);; 中国地质调查局项目“区域成矿图件编制与相关找矿问题研究”(12120113079400)

作者(Author): 刘芳;宋史刚;丁振举;周宗桂;张振飞;梅燕雄;

Email:

DOI:

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