The Jbel Saghro Au(–Ag, Cu) and Ag–Hg Metallogenetic Province: Product of a Long-Lived Ediacaran Tectono-Magmatic Evolution in the Moroccan Anti-Atlas

Abstract

The Jbel Saghro is interpreted as part of a long-lived silicic large igneous province. The area comprises two lithostructural complexes. The Lower Complex consists of folded metagreywackes and N070–090°E dextral shear zones, which roughly results from a NW–SE to NNW–SSE shortening direction related to a D1 transpressive tectonic stage. D1 is also combined with syntectonic plutons emplaced between ca. 615 and 575 Ma. The Upper Complex is defined by ash-flow caldera emplacements, thick and widespread ignimbrites, lavas and volcaniclastic sedimentary rocks with related intrusives that were emplaced in three main magmatic flare ups at ca. 575, 565 and 555 Ma. It lies unconformably on the Lower Complex units and was affected by a D2 trantensive tectonic stage. Between 550 and 540 Ma, the magmatic activity became slightly alkaline and of lower extent. Ore deposits show specific features, but remain controlled by the same structural setting: a NNW–SSE shortening direction related to both D1 and D2 stages. Porphyry Au(–Cu–Mo) and intrusion-related gold deposits were emplaced in an earlier stage between 580 and 565 Ma. Intermediate sulfidation epithermal deposits may have been emplaced during lull periods after the second and (or) the third flare-ups (560–550 Ma). Low sulfidation epithermal deposits were emplaced late during the felsic alkaline magmatic stage (550–520 Ma). The D2 stage, therefore, provided extensional structures that enabled fluid circulations and magmatic-hydrothermal ore forming processes.

The Cu–Pb–Zn-bearing veins of the Bou Skour deposit (Eastern Anti-Atlas, Morocco): structural control and tectonic evolution

“…760-740 Ma and 660-640 Ma occur in the Bou Azzer-Siroua Pan-African suture zone [Blein et al, 2014a, El Hadi et al, 2010, Inglis et al, 2005, Triantafyllou et al, 2016. To the northeast of the AAMF, the Pan-African units correspond to the Early Hindermeyer et al [1977], Tuduri et al [2018], Hejja et al [2020], Aabi et al [2020], and this work.…”

A 571 million‐year‐old alkaline volcanic lake photosynthesizing microbial community, the Anti‐atlas, Morocco

“…The microbialitic successions are encased in a volcanic complex exhibiting evidence of subaqueous explosive and effusive volcanic activities. Additionally, the sedimentary and volcanosedimentary features indicate deposition in an alluvial and colluvial environment (Álvaro et al., 2010; Tuduri et al., 2018; Walsh et al., 2012). The microbialitic and non‐microbialitic features, together with the vertical arrangement of the facies, indicate low‐energy lacustrine conditions punctuated by high‐energy events.…”

“…Most rocks in the Saghro inlier and the northernmost reaches of the Bou Azzer inlier are comprised of Ediacaran volcanic rocks and clasts belonging to the Ouarzazate Supergroup associated with sub‐volcanic plutons and dikes (Walsh et al., 2012). The Ouarzazate Supergroup was previously subdivided into lower volcaniclastic, volcanic, and granitic lithologies labeled "XIIIm," and an upper "XIIIs" unit dominated by volcaniclastic and volcanic rocks isolated by an unconformity (Thomas et al., 2004; Tuduri et al., 2018; Walsh et al., 2012). Most of the volcanic rocks are peraluminous to metaluminous and range from andesitic basalts to rhyolitic lithologies with high‐K calc‐alkaline to shoshonitic affinities (Walsh et al., 2012).…”

“…The structural, sedimentological, and volcanic features indicate subaerial effusive volcanic activity from several active centers containing calderas, and subaerial sedimentary sequences of alluvial, fluvial, and colluvial origin. The main known Caldera complexes in the central and eastern Anti‐atlas are Achkoukchi in Sirwa, Oued Dar'a, and Qal'at Mgouna in Jbel Saghro (Thomas et al., 2002; Tuduri et al., 2018; Walsh et al., 2012).…”

Editorial for Special Issue “Structural Control of Mineral Deposits: Theory and Reality”

“…Song et al [23] examine the consequences of the telescoping of two mineralized systems (a subsequent epithermal system affects a primary porphyric one within the Tiegelongnan Porphyry and the epithermal overprinting Cu (Au) deposit, Central Tibet, China) with a focus on the role of the dislocation effects on ore reserve calculations and future deposits discoveries. Tuduri et al [24] suggest an original way to demonstrate the genetic link between mineralization and magmatism by establishing that both are developed in the same regional tectonic context, in the highly mineralised Moroccan Anti-Atlas. This contribution represents an indirect but efficient way to relatively date the emplacement of magmatism and mineralization formations, and their relationships.…”