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Stratigraphy, petrography and major element mineral chemistry of the Wadi Qutabah Layered Mafic Complex, Yemen

University of British Columbia

Little is known about the recently discovered Wadi Qutabah Layered Mafic Intrusion in Yemen. It possesses significant potential for the discovery of economic platinum-group element (PGE) and Ni-Cu-Co mineralization, and is believed to be part of the larger Suwar-Wadi Qutabah Layered Mafic Complex. The intrusion was recently dated as being Neoproterozoic in age (~638.5Ma). The current estimated size of the complex is ~250km². Mineralization has been identified in the Suwar area which lies ~30km to the southeast of Wadi Qutabah. Anomalous platinum mineralization was identified in stream sediment samples that run off of the Wadi Qutabah intrusion. Little is known about the stratigraphy, mineralization, layering and geochemistry of the rocks from Wadi Qutabah. Drill cores from 14 drill holes were used to study the stratigraphy, petrography and mineral chemistry of the Wadi Qutabah intrusion. Methods employed were drill core logging, petrographic analysis and mineral grain analyses using the Scanning Electron Microscope (SEM/EDS). Rocks from the Wadi Qutabah intrusion are medium to coarse-grained cumulate norites and gabbros with minor anorthosite, pyroxenite, and localized massive sulphide layers. Correlation of the layering was accomplished in a broad scale as a result of modal and phase layering, stratigraphic position and textural variations. Lithological unit codes were created for the purposes of correlation and identification for this study. Each of the units/layers is host to unique textures, mineralogy and stratigraphic position. They correlate across stratigraphy from drill hole to drill hole, but lateral changes in alteration and thickness are common. Significant changes in chemistry occur at the top of unit 5a (augite norite) which occurs in the middle of the section. The reversal in chemistry towards more primitive compositions up stratigraphy, are the result of injection of new hot primitive magma. Comparison of the mineralogy and chemistry of the Wadi Qutabah intrusion with other layered intrusions indicates that the complex is >2km in thickness and that there are prospective areas for PGE mineral exploration. Discriminant analysis of augite composition suggests that the magmas are derived from within plate tholeiites. A composite stratigraphic column yields a section ~500m thick in the area.

Text

2013-03-23

Attribution-NonCommercial-NoDerivatives 4.0 International

http://hdl.handle.net/2429/44059

Environmental Sciences

University of British Columbia

UBCO

http://creativecommons.org/licenses/by-nc-nd/4.0/