Age and depositional environment of the Draa Sfar massive sulfide deposit, Morocco |
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| Authors: | C Moreno R Sáez F González G Almodóvar M Toscano G Playford A Alansari S Rziki A Bajddi |
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| Institution: | (1) Departamento de Geología, Universidad de Huelva, Huelva, Spain;(2) Earth Sciences, School of Physical Sciences, University of Queensland, Brisbane, Australia;(3) Département de Géologie, Université Cadi Ayyad, Marrakech, Morocco;(4) Compagnie minière des Guemmassa (CMG)/Managem/ONA, Marrakech, Morocco |
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| Abstract: | The Draa Sfar mineralization consists of two main stratabound orebodies, Sidi M’Barek and Tazacourt, located north and south
of the Tensift River (“Oued Tessift”), respectively. Each orebody is comprised by at least two massive sulfide lenses. The
hosting rocks are predominantly black shales, although minor rhyolitic rocks are also present in the footwall to the southern
orebody. Shales, rhyolitic volcanic rocks, and massive sulfides are all included into the Sarhlef Series, which is recognized
as one of the main stratigraphic units of the Moroccan Variscan Meseta. Hydrothermal activity related with an anomalous thermal
gradient, together with a high sedimentation rate in a tectonically driven pull-apart marine basin, favored the accumulation
of organic-rich mud in the deepest parts of the basin and the sedimentary environment suitable for massive sulfide deposition
and preservation. This took place by replacement of the hosting unlithified wet mud below the sediment–water interface. Geochemical
data suggest a sedimentary environment characterized by oxic water column and anoxic sediment pile with the redox boundary
below the sediment–water interface. The low oxygen availability within the sediment pile inhibited oxidation and pyritization
of pyrrhotite. Biostratigraphic analysis, based on the palynological content of the hosting black shales, restricts the age
of the sulfides to the Asbian substage (mid-Mississippian). This age is consistent with earlier geochronological constraints. |
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| Keywords: | Draa Sfar Massive sulfide deposits Black shales Biostratigraphy Morocco |
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