Native antimony emplaced by methane‐rich hydrothermal fluid in an orogenic fault‐zone

Abstract

Antimony‐rich gold deposits represent a subclass of orogenic hydrothermal systems. The study of the Lapa gold deposit in the Abitibi greenstone belt shows that antimony occurs during two different stages: (1) as early prograde Sb–Ni disseminated sulphides in talc schists, associated with CO2‐bearing fluids, and (2) as a late native antimony association, associated with methane‐bearing fluids indicating a reducing environment. Methane could be related to the serpentinization of the ultramafic rocks of the Piché Group hosting the Lapa deposit. Several deposits display the same methane antimony association along fault zones.

Methane in sulphides from gold-bearing deposits, Britain and Ireland

“…These observations add weight to previous suggestions that methane plays a role in orogenic gold mineralisation (Naden and Shepherd 1989; Gaboury 2013; Goldfarb and Groves 2015; Jébrak et al 2017). The data could be viewed as showing that the most methanic of the sample set are a guide to gold-bearing deposits.…”

“…One model for orogenic gold deposits involves the role of methane for complexing and precipitating gold (Naden and Shepherd 1989; Gaboury 2013; Goldfarb and Groves 2015; Jébrak et al 2017). This was tested using deposits from Britain and Ireland (Figure 1) by assessing if the compositions of gases in gold deposits are distinct among samples in three distinct settings.…”

Modelling Seismically Induced Mesothermal Goldfields along the Deep-Rooted Cadillac-Larder Lake Fault, Abitibi, Canada

“…These fluids are associated either with late orogenic midcrust reheating or with subduction-related processes and subsequent fluid entrapment in the mantle wedge [5]. In the region of the CLLF, it is likely that the abundant CO 2 inflow, reflected by ubiquitous carbonate alterations (e.g., [40,98,106,107]), is supplied by vertical fluid transfers from subamphibolite devolatilized Pontiac sediments enrooted at the CLLF's footwall (Figure 9), as suggested by the LITHOPROBE profiles [108]. It is worth noting, however, that both midcrust and mantle fluid source models are remarkably well supported by present-day observations of crustal fluid transfers following major earthquakes in active convergent zones.…”

Gold and aurostibite from the metaturbidite-hosted Au–Zn–Pb–Ag Hera deposit, southern Cobar Basin, central NSW, Australia: geochemical and textural evidence for gold remobilisation

“…Of relevance to this present study is the mineral aurostibite (AuSb 2 ), a member of the pyrite group where gold is alloyed with antimony and was first described by Graham and Kaiman (1952) from the Giant mine at Yellowknife, Northwest Territories and the Chesterville mine of Ontario, Canada, both being quartz-vein hosted orogenic gold deposits (Shelton et al , 2004; Ispolatov et al , 2008). Since then, it has been described from many deposits including, but not restricted to, the quartz-vein hosted orogenic Mobale gold mine, Kivu, Democratic Republic of Congo (Jedwab et al 1992; Milesi et al , 2006), metamorphosed Sulitjelma VMS deposit of northern Norway (Cook, 1992, 1996), quartz-vein hosted orogenic Kharma Sb deposit of Bolivia (Dill et al , 1995), quartz-vein hosted orogenic West Gore Sb-Au deposit of Nova Scotia, Canada (Kontak et al , 1996), hydrothermal quartz-vein hosted Hillgrove gold-antimony deposit of northeastern NSW, Australia (Ashley et al , 2000), intrusion-related Au–Sb A deposit of New Brunswick, Canada (Cabri et al , 2007; Deschenes et al , 2009; Ravenelle et al , 2008; Watters et al , 2008), intrusion-related Darasun deposit of Eastern Transbaikal, Russia (Bryzgalov et al , 2007; Spiridonov et al , 2010), quartz-vein hosted orogenic Passagem de Mariana gold mine, Brazil (Oberthur and Weiser, 2008), carbonaceous clastic sediment-hosted Suzdal gold deposit of eastern Kazakhstan (Kovalev et al , 2009), metamorphosed mafic-ultramafic hosted orogenic Lapa deposit, Abitibi Belt, Canada (Simard et al , 2013; Jebrak et al , 2016), intrusion-related Mokrsko-West gold deposit of the Bohemian Massif, Czech Republic (Zacharias et al , 2014), metavolcanic hosted Pirunkoukku gold occurrence of northern Finland (Novoselov et al , 2015), the Krasna Hora deposit of the Czech Republic (Zacharias and Nemec, 2017), and most recently, the intrusion-related Oleninskoe Au–Ag deposit of the Kola Peninsula, Russia (Kalinin et al , 2019).…”