The Bou Dahar Jurassic carbonate-hosted Pb–Zn–Ba deposits (Oriental High Atlas, Morocco): Fluid-inclusion and C–O–S–Pb isotope studies

Abstract

The Bou Dahar Pb-Zn-Ba (±Sr) is hosted in the Lower and Middle Liassic carbonate platform in the oriental High Atlas of Morocco. The paragenetic sequence includes quartz-pyrite-melnicovite-sphalerite-galenacalcite-barite ± fluorite-± celestite. Fluid-inclusion studies were conducted on sphalerite (early mineralizing stage) and barite, and celestite (late mineralizing stage). These studies reveal two end-member fluids, a hot (~143°C) and saline fluid (~23 wt.% NaCl eq.) and a cooler (b 50°C) and diluted fluid (~5 wt.% NaCl eq.). Based on fluid-inclusion and CO -S isotope studies, a conclusion is reached that the Bou Dahar ore deposits were formed by the mixing of two fluid-a diluted, SO 2− 4-rich fluid, and an 18 O-enriched basinal brine that carried Pb, Zn, and Ba. The sulfur required for the precipitation of sulfides was generated by the thermochemical sulfate reduction of dissolved sulfate (SO 4 2−) of the Mesozoic seawaters, and delivered to the site of ore deposition. The sulfur of sulfate minerals was derived directly from these dissolved SO 4 2. The Pb isotope compositions are homogenous with 206 Pb/ 204 Pb, 207 Pb/ 204 Pb, and 208 Pb/ 204 Pb ratios ranging from 18.124 to 18.183, 15.630 to 15.634, and 38.325 to 38.440 respectively. This Pb isotope composition is indicative of an upper crust and orogene reservoirs as the source of lead and other metals. The emplacement of mineralization occurred during the Eocene-Miocene Alpine orogeny, and tectonic burial and compression were the driving forces behind the circulation of the orogenic-brines. These ore-forming fluids migrated, along thrusting regional E-W and NE-SW deep-seated faults, to the confined carbonate-Liassic reservoir.

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

“…Supergene mineral assemblages are extensively developed, with the oxidized ore zones extending as deep as 120 m and accounting for nearly 60% of the extracted ore [5]. The geometry of the orebodies that parallel the Atlasic ENE-WSWand E-W-trending faults [45][46][47] coupled with Pb-Pb geochronological data [5] suggest that the MVT mineralizing event occurred during the Late Miocene at <15 Ma [5,26,28], consistent with the time span determined for most of the north African MVTs [29,48].…”

“…Earlier studies indicate that the primary sulfide mineralization is of Mississippi Valley-type (MVT) affiliation [5,[26][27][28]. Major advances in understanding the genesis of MVT mineralization have been accomplished over the last two decades, principally as a result of field observations, mineralogical assemblages, and textural characterization, along with fluid inclusions and stable and radiogenic isotope geochemistry [5,[26][27][28][29].…”

The role of the structures on the fluorite mineralization: Insight to fluid inclusion and alteration map of the Laal-kan fluorite deposit, NW Iran

“…The micro thermometric results revealed that the first ice melting temperature, known as eutectic temperature (Te), in the study district vary between -52/-17.8 ºC, respectively. All of these data indicated that the eutectic temperature of the studied fluorite samples was far below the eutectic temperature of NaCl-H 2 O system (Bakker and Doppler, 2016), which can be due to the existence of some other salts such as CaCl 2 (-52 ºC) and perhaps MgCl 2 (-35 ºC) as well as NaCl-H 2 O in hydrothermal fluids responsible for the formation of fluorite in these districts (Rddad and Bouhlel, 2016;Rezaei Azizi et al, 2018a;Rezaei Azizi et al, 2018b) (Fig. 6a).…”

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).…”