云南省勐腊县曼洒菱铁矿床Fe同位素特征及其地质意义

摘要

首次研究了云南省勐腊县曼洒菱铁矿床碳酸盐岩层中菱铁矿的Fe同位素组成特征,并利用菱铁矿Fe同位素对矿床成因及成矿环境进行了制约.曼洒矿区菱铁矿δ56 Fe值变化范围为-0.337‰～-0.201‰,平均值为-0.261‰;δ57Fe范围为-0.518‰～-0.289‰,平均值为-0.380‰.菱铁矿样品Fe同位素组成非常均一,富集铁的轻同位素.通过大量对比分析,提出曼洒铁矿床的成矿作用与海底热液活动有关,为含矿热水溶液喷溢出海底后快速堆积成矿,矿床形成于局限深水洼地的还原性环境.%Iron isotopic compositions of siderite minerals from the carbonate rocks in the Mansa siderite deposit of Mengla County in Yunnan Province were studied for the first time in order to discuss the genesis and ore-forming environment of the deposit.Fe isotopes of siderite from the Mansa deposit show a relatively small negative range:~6Fe values of siderite range from-0.337‰ to-0.201‰ (averagely-0.261‰),whereas δ57Fe val ues from-0.518‰ to-0.289‰ (averagely-0.380‰),implying that the Fe isotopic compositions are rather homogeneous and enriched in light iron isotope.Detailed Fe isotope studies of the Mansa siderite deposit show a close relationship between metallogenesis and hydrothermal process,and hence the deposit was formed in a partial submarine environment with rapid accumulation after the effusion of the ore-bearing hydrothermal solution.