Mineralogy and Genesis of the Polymetallic and Polyphased Low Grade Fe-Mn-Cu Ore of Jbel Rhals Deposit (Eastern High Atlas, Morocco)

Abstract

The Jbel Rhals deposit, located in the Oriental High Atlas of Morocco, hosts a polymetallic Fe-Mn-Cu ore. Large metric veins of goethite and pyrolusite cut through Paleozoic schists that are overlaid by Permian-Triassic basalts and Triassic conglomerates. The genesis of this deposit is clearly polyphased, resulting from supergene processes superimposed over hydrothermal phases. The flow of Permian-Triassic basalts probably generated the circulation of hydrothermal fluids through the sedimentary series, the alteration of basalts and schists, and the formation of hydrothermal primary ore composed of carbonates (siderite) and Cu-Fe sulfides. Several episodes of uplift triggered the exhumation of ores and host rocks, generating their weathering and the precipitation of a supergene ore assemblage (goethite, pyrolusite, malachite and calcite). In the Paleozoic basement, Fe-Mn oxihydroxides are mostly observed as rhombohedral crystals that correspond to the pseudomorphose of a primary mineral thought to be siderite; goethite precipitated first, rapidly followed by pyrolusite and other Mn oxides. Malachite formed later, with calcite, in fine millimetric veins cutting through host-rock schists, conglomerates and Fe-Mn ores.

Origin of the Moroccan Touissit-Bou Beker and Jbel Bou Dahar Supergene Non-Sulfide Biomineralization and Its Relevance to Microbiological Activity, Late Miocene Uplift and Climate Changes

“…In this respect, it should be emphasized that large-scale, vertical, positive movements were able to produce uncapping and weathering of the primary hypogene sulfides by creating a gradient for the percolation of meteoric fluids. In Morocco, weathering episodes have been related to four main Atlasic geodynamic events referred to as D 0 (Late Cretaceous), D 1 (Late Eocene), D 2 (Early Miocene), and Late Miocene to Recent, consistent with the conclusions of [30,42,73,[110][111][112].…”

Agates from Western Atlas (Morocco)—Constraints from Mineralogical and Microtextural Characteristics

“…All gems contain assemblages of similar solid inclusions, which are mainly represented by hematite, goethite, rutile, as well as barite, copper sulfides, and carbonates, which were probably formed during the post-magmatic processes of the hydrothermal stage and/or the tectonic processes which affected the area of High Atlas during the Alpine orogen system. Asni and Agouim are located close to the main Atlas mountain ridge as well as to the main tectonic lines, so the hydrothermal solution had a greater opportunity to alter agates in that area, compared to Kerrouchen or Sidi Rahal regions, which are located outside the main tectonic zones [18,22,23].…”

Multistage genesis of the late Cretaceous manganese karst-hosted Tasdremt deposit (High Atlas, Morocco)

“…They could therefore have enabled the Tasdremt metal association (Mn, Ba and Pb). Similarly, MVT and other base-metal deposits are widespread in Jurassic rocks in the Atlas belt (i.e., Choulet et al 2014;Bouabdellah and Sangster 2016;Buatier et al 2016;Verhaert et al 2017Verhaert et al , 2018 and could act as a potential source of metals, leading to the enrichment, up to several percents in Pb, in Tasdremt (Tables 1 and 2). The enrichment in other metals (Cu, Mo, As, V, and Zn; Fig.…”