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报道了粤西大降坪黄铁矿矿床的Mo同位素组成,其Ⅲ号矿体的δ97/95Mo变化范围较小,为-0.02‰～0.29‰,平均为0.18‰(n=3);Ⅳ号矿体的δ97/95Mo变化范围大,为-0.70‰～0.62‰(n=8),尤其是主矿层处的5个样品均以富集轻同位素为特征.Ⅲ号矿体与Ⅳ号矿体明显不同的Mo同位素组成可能反映了两个矿体形成于不同的成矿环境,并可能具有不同程度的后期热液改造和叠加作用.Ⅲ号矿体可能形成于一种开放的生物作用较强烈的缺氧环境,而Ⅳ号矿体形成于一种封闭或半封闭的弱氧化的局限环境.Ⅳ号矿体主成矿层位的δ97/95Mo整体偏负且具有随成矿层位的升高而增大的特点,反映了在局限环境条件下Mo同位素的分馏不同于海洋开放环境,可能存在Mo的动力学分馏效应.Ⅳ号矿体Mo同位素组成变化范围大于Ⅲ号矿体,还可能反映该矿体海底喷流沉积形成后,受到了较强的后期热液改造和叠加作用.因此,Mo同位素可以作为一种指示成矿流体以及成矿环境的有效示踪剂.
The Mo isotopic composition of the Dajianping pyrite deposit in western Guangdong was reported. The δ97 / 95Mo range of No.3 ore body is relatively small, ranging from -0.02 ‰ to 0.29 ‰ with an average of 0.18 ‰ (n = 3) The δ97 / 95Mo range of the ore body ranges from -0.70 ‰ to 0.62 ‰ (n = 8), especially the five samples at the main ore bed are all characterized by enrichment of light isotopes. Significantly different Mo isotopic composition may reflect the formation of two ore bodies in different metallogenic environments, and may have varying degrees of late hydrothermal transformation and superimposition.Ⅲ ore body may be formed in an open biological role is more intense While the orebody of No.4 formed in a confined or semi-closed, weakly oxidized confined environment.The δ97 / 95Mo of main orebody of No.4 orebody is generally negative and has the tendency to increase with the increase of ore-forming beds The results show that the Mo isotope fractionation may be different from the marine open environment under limited environmental conditions and there may be a kinetic fractionation effect of Mo. The variation of Mo isotope composition of orebody Ⅳ is larger than that of orebody Ⅲ and may also reflect the After the formation of the submarine jet deposits, the ore body was subjected to strong hydrothermal reformation and stacking Effect. Thus, Mo isotopes can serve as an effective tracer indicate ore fluid environment and mineralization.