Basinal Brines at the Origin of the Imiter Ag-Hg Deposit (Anti-Atlas, Morocco): Evidence from LA-ICP-MS Data on Fluid Inclusions, Halogen Signatures, and Stable Isotopes (H, C, O)

Abstract

International audienc

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

“…The strong association of mineral deposits with fluids of moderate to high salinities, suggests interpretations favouring the influence of basinal brines in the ore-forming processes [40,41]. Indeed, processes involving basin-related and(or) surface-related brines resulting from evaporation of seawater in Triassic basins in the formation of ore deposits, up to now interpreted as, deposits related to the late Neoproterozoic felsic magmatic event [42][43][44][45][46][47][48] have been defended by several recent works [40,41,49] although the debate is still open [50]. This controversy mainly concerns the Bou Azzer (Co-Ni-), Imiter (Ag-Hg) and Zgounder (Ag-Hg) mines that represent the main three world-class ore deposits of the Moroccan Anti-Atlas after the Akka gold mine was closed few years ago.…”

“…This controversy mainly concerns the Bou Azzer (Co-Ni-), Imiter (Ag-Hg) and Zgounder (Ag-Hg) mines that represent the main three world-class ore deposits of the Moroccan Anti-Atlas after the Akka gold mine was closed few years ago. The Imiter concentration has been proposed to be associated with the 550 ± 3 Ma rhyolitic magmatism [51], a hypothesis recently controverted by Ar-Ar geochronology [38] and palaeo-fluid geochemistry investigations [41]. The Zgounder deposit is supposed to be emplaced around 564 ± 5 Ma at the same time as rhyolitic intrusions [46,52] although fluid geochemistry would suggest a Triassic fluid contribution [41,49] sedimentary.…”

Medieval Silver Production Around Sijilmâsa, Morocco

“…Due to geodynamic events affecting the Anti‐Atlas, a second fluid input, around 300–250 Ma, reworked the older Ag deposits by lixiviation producing the implementation of the main rich‐Ag ores (Essarraj et al . ). Calculated Pb–Pb model ages of ores from Imiter (Pasava , Levresse et al , ; Milot et al , and this study) are consistent (323 ± 56 Ma age and a Th/U ratio of 3.78 ± 0.08) whereas the slags from Imiter have a 270 ± 78 Ma age and a Th/U ratio of 3.89 ± 0.03.…”

Genesis of the Huangshaping W–Mo–Cu–Pb–Zn deposit, South China: Role of magmatic water, metasomatized fluids, and basinal brines during intra‐continental extension

“…Lithospheric extension and subcrustal lithospheric thinning may be key drivers of hot, metal‐rich basinal brine migration, responsible for the formation of large‐scale Pb–Zn polymetallic ore deposits (Betts & Lister, ), Mississippi Valley‐type deposits (MVT; Hanilçi & Öztürk, ), and Pb, Zn, Ag, Au, and/or barite sedimentary exhalative (Sedex) deposits (Diehl et al, ; Li & Xi, , ). However, the origin of fluids and the degree of interaction between basinal brines, magmatic‐metasomatized fluid, and meteoric water in a magmatic‐hydrothermal polymetallic mineralization system, generated during intra‐continental extension, are still unclear (Essarraj et al, ; Hofstra et al, ; Li, Watanabe, Xi, & Yonezu, ; Li, Xi, Wu, & Watanabe, ; Rddad & Bouhlel, ; Sun, Li, Danišík, et al, ; Sun, Li, Evans, et al, ; Wang, Yang, et al, ; Wang, Wei, et al, ).…”

“…However, the origin of fluids and the degree of interaction between basinal brines, magmatic-metasomatized fluid, and meteoric water in a magmatic-hydrothermal polymetallic mineralization system, generated during intra-continental extension, are still unclear (Essarraj et al, 2016;Hofstra et al, 2016;Li, Watanabe, Xi, & Yonezu, 2013;Li, Xi, Wu, & Watanabe, 2013;Rddad & Bouhlel, 2016;Sun, Li, Danišík, et al, 2017;Sun, Li, Evans, et al, 2017;Wang, Yang, et al, 2017;Wang, Wei, et al, 2017).…”