Arrens Zn (Pb), Ba Devonian deposit, Pyrénées, France: an exhalative-sedimentary-type deposit similar to Meggen

Abstract

Abstract. The Perrefitte anticlinorium district in the Paleozo[c province of the Pyrenees contains abundant mineral occurrences, prospects, and old mines in the upper volcano-sedimentary layer of the Ordovician and Devonian sediments which have been metamorphosed in the greenschist to amphibolite facies. Although of different lithologic environments, the mineralization shows, as everywhere in the Pyrenees, many common characteristics. However, the Arrens deposit outcropping over 5 km on both limbs of a syncline displays specific characteristics: abundant barite with lateral Zn (Pb) Ba zoning, exceptionally thick subreef (?) footwall limestone overlain by black siltstone, abundant Ba silicate, in particular celsianite, locally cymrite, and siliceous, sedimentary-hydrothermal gangue.Due to deformation, such as tight folds and flow cleavage, the paleogeography of the Arrens geological environment could not be precisely reconstructed. However, the deposit is very likely located in an unstable shelf zone. Lithology underwent many changes close to the synsedimentary faults including at Arrens a limestone shelf facies and some small basins of black siltstone, at the bottom of which mineralization occurs. As all the mineralization of the Pyrenees Paleozoic, the deposit is of the exhalative or hydrothermal sedimentary type and bears some analogies with other exhalative deposits throughout the world. (The word "exhalative" is etymologically related to gases. Although "hydrothermal" is a more exact word as it pertains to hot water, "exhalative" will be used in this paper, being of most current usage.)

Structural Control on the Formation of Pb-Zn Deposits: An Example from the Pyrenean Axial Zone

“…SEDEX deposits are sedimentary controlled and syn-to diagenetic, and sulfides in them are laminated and included into the bedding [2]. In our study area, Pyrenean Pb-Zn mineralizations have been previously described as SEDEX by many authors [24,[28][29][30]75,76]. The origin of several world-class Pb-Zn deposits is debated as well.…”

Relationships between the occurrence of accessory Ge-minerals and sphalerite in Variscan Pb-Zn deposits of the Bossost anticlinorium, French Pyrenean Axial Zone: Chemistry, microstructures and ore-deposit setting

“…More usually, whenever Ge is present, it is enriched in the sphalerite (ZnS) lattice rather than as independent Ge-minerals (Reyx, 1973;Johan et al, 1983;Laforet et al, 1981;Bernstein, 1985;Cook et al, 2009Cook et al, , 2015. These Geminerals may be brunogeierite (GeFe 2 O 4 ), argutite (GeO 2 ), Ge-chloritoid (carboirite, FeA1 2 GeO 5 (OH) 2 ), rare briartite (Cu 2 (Fe, Zn)GeS 4 ), as well as Ge-bearing lepidomelane, titanite, garnet, zoisite, chlorite, quartz, allanite, and magnetite (Laforet et al, 1981;Johan et al, 1983;Bernstein, 1985;Pouit and Bois, 1986;Johan and Oudin, 1986). The formation of Ge-minerals in the Pyrenean deposits is poorly documented until now except for Aye et al (1978) and Johan and Oudin (1986) who suggested a possible link with regional metamorphism, based on paragenetic analysis.…”

Geochemical evidences of sedimentary-exhalative origin of the shale-hosted PGE–Ag–Au–Zn–Cu occurrences of the Prades Mountains (Catalonia, Spain): trace-element abundances and Sm–Nd isotopes

“…Ba-feldspar rocks appear to be more common in exhalative ores; celsian forms thick monomineralic lenses, as in Aberfeldy, Scotland (Fortey and Beddoe-Stephens, 1982;Willan and Coleman, 1983). Celsian has been also reported in Arrens, Pyrenees (Pouit and Bois, 1986), and in Broken Hill, Australia (Lottemoster, 1989;Parr, 1992). In Zamora, Spain, Moro et al (2001) reported celsian lenses with hyalophane and cymrite, interlayered in apatite and massive sulfide layers.…”