Molybdenum isotopic composition of molybdenite and the fertility potential of the Ekomédion U–Mo prospect, SW Cameroon

IF 1.1 4区 地球科学 Q3 GEOCHEMISTRY & GEOPHYSICS
V. F. Embui, Cheo Emmanuel, Suh, Bernd Lehmann, Lukáš Ackerman
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引用次数: 0

Abstract

We present Mo isotope data for molybdenite from the Ekomédion U–Mo prospect, SW Cameroon, a Late Neoproterozoic granite–pegmatite–quartz vein system. Disseminated and veinlet-controlled molybdenite in granite and pegmatitic pods yields a narrow range of δ 98 Mo values from – 0.06 to + 0.24 ‰, with two overlapping populations of + 0.03 ± 0.07 ‰ (n = 4) in granite, and slightly heavier of + 0.11 ± 0.10 ‰ (n = 5) in pegmatite. By contrast, molybdenite from a quartz– muscovite vein has an isotopically heavy δ 98 Mo value of + 1.61 ‰. We interpret this trend from granite through pegmatite to vein system towards isotopically heavy Mo to reflect the fractionation of an evolving magmatic–hydrothermal system. Furthermore, the LREE-enriched bulk-rock patterns with largely negative Eu anomalies and the overall enrichment of HREE in zircon indicate plagioclase fractionation as the dominant petrogenetic process during melt evolution. Furthermore, the presence of accessory ilmenite indicates relatively reducing conditions of the melt system, unfavorable for significant Mo accumulation. Therefore, the Ekomédion granite system seems to have limited economic potential for molybdenum despite the advanced degree of magmatic evolution.
喀麦隆西南部Ekomédion U–Mo矿床辉钼矿的钼同位素组成和肥力潜力
我们提供了喀麦隆西南部Ekomédion U–Mo矿床辉钼矿的Mo同位素数据,该矿床为新元古代晚期花岗岩-伟晶岩-石英脉系统。花岗岩和伟晶岩荚中的浸染状和细脉控制的辉钼矿产生的δ98 Mo值范围很窄,从–0.06‰到+0.24‰,花岗岩中有两个重叠种群,为+0.03±0.07‰(n=4),伟晶岩中稍重,为+0.11±0.10‰(n=5)。相比之下,石英-白云母脉的辉钼矿具有+1.61‰的同位素重δ98Mo值。我们解释了从花岗岩到伟晶岩再到矿脉系统向同位素重Mo的趋势,以反映不断演化的岩浆-热液系统的分馏。此外,LREE富集的块状岩石模式具有很大程度的负Eu异常,锆石中HREE的总体富集表明斜长石分馏是熔体演化过程中的主要岩石成因过程。此外,副钛铁矿的存在表明熔体系统的相对还原条件,不利于Mo的显著积累。因此,尽管岩浆演化程度较高,但Ekomédion花岗岩系统对钼的经济潜力似乎有限。
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来源期刊
Journal of Geosciences
Journal of Geosciences GEOSCIENCES, MULTIDISCIPLINARY-MINERALOGY
CiteScore
2.30
自引率
7.10%
发文量
15
审稿时长
>12 weeks
期刊介绍: The Journal of Geosciences is an international peer-reviewed journal published by the Czech Geological Society with support from the Czech Geological Survey. It accepts high-quality original research or review papers dealing with all aspects of the nature and origin of igneous and metamorphic rocks. The Journal focuses, mainly but not exclusively, on: -Process-oriented regional studies of igneous and metamorphic complexes- Research in structural geology and tectonics- Igneous and metamorphic petrology- Mineral chemistry and mineralogy- Major- and trace-element geochemistry, isotope geochemistry- Dating igneous activity and metamorphic events- Experimental petrology and mineralogy- Theoretical models of igneous and metamorphic processes- Mineralizing processes and mineral deposits. All the papers are written in English, even though they may be accompanied by an additional Czech abstract. Each contribution is a subject to peer review by at least two independent reviewers, typically at least one from abroad. The Journal appears 2 to 4 times a year. Formally it is divided in annual volumes, each of them including 4 issues.
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