V. F. Embui, Cheo Emmanuel, Suh, Bernd Lehmann, Lukáš Ackerman
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Molybdenum isotopic composition of molybdenite and the fertility potential of the Ekomédion U–Mo prospect, SW Cameroon
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.
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.