Igneous Rock Associations 14. The Volcanic Setting of VMS and SMS Deposits: A Review

Abstract

SUMMARYVolcanogenic massive sulphide (VMS) deposits and seafloor massive sulphide (SMS) deposits have a spatial and genetic connection with contemporaneous volcanism. The control exerted by the volcanic succession (e.g. rock type, architecture and facies) on the nature and style of the ore and alteration (e.g. subsea-floor replacement vs. exhalative, or discordant vs. conformable) is significant, making it imperative to understand the local volcanology in developing better genetic and exploration models. Three VMS deposit groupings collectively represent a high proportion of cases: (1) deposits associated with complexes of submarine felsic domes, cryptodomes, lobe-hyaloclastite flows and/or blocky lavas, and their reworked equivalents; (2) deposits associated with thick piles of pumiceous felsic pyroclastic rocks, suggesting a caldera context; and (3) deposits associated with mafic volcanic footwalls and/or with sedimentary hosts, including significant deposits such as Windy Craggy (~300 Mt) in British Columbia. With regard to number (2) above, demonstrating the presence of a caldera in ancient successions can be difficult because silicic calderas tend to be large and exceed the limits of deposit-scale investigations. Furthermore, there is no consensus regarding what a large submarine caldera should look like, i.e., no accepted facies model exists showing the distribution of rock types. But without thick piles of pumiceous felsic pyroclastic deposits, arguing for a large submarine caldera is a challenge.

Microplate Evolution in the Queen Charlotte Triple Junction & Explorer Region: New Insights From Microseismicity

“…A weak lithosphere is implied by high heat flow values (average of 220 mWm −2 around the TWVF (Hyndman et al., 1978)), extensive volcanism and shear faulting, along with a balancing component of compression arising from Pacific plate obliquity as indicated by comparatively high shape ratios (northern RDFE, R = 0.68; TWVF, R = 0.86). The thermal regime may reflect a mantle plume influence (Chase, 1977; Cousens et al., 1985) which is supported by a basalt composition in the TWVF that falls at the enriched end of the mid‐ocean ridge basalt (MORB) spectrum and overlaps isotopically with the Kodiak‐Bowie seamount chain (Allan et al., 1993; Cousens, 2010; Cousens et al., 1985).…”

“…More recent geochemical (Allan et al., 1993) and geomorphological analyses (Rohr & Furlong, 1995; Rohr & Tryon, 2010) support the hypothesis that the TWVF is the manifestation of leaky transform tectonics along the ∼40 km wide transtensional stepover between the QCF and RDFE. Nonetheless, basalts of the TWVF are isotopically consistent with Kodiak‐Bowie seamount chain, and its location at the southern extrapolation of the chain may indicate that the southeast outskirts of the hotspot may just barely extend to reach the lithosphere beneath the TWVF (Cousens, 2010).…”

Resolving the Relative Timing of Au Enrichment in Volcanogenic Massive Sulfide Deposits Using Scanning Electron Microscopy-Mineral Liberation Analyzer: Empirical Evidence from the Ming Deposit, Newfoundland, Canada

“…9; McPhie et al, 1993). It is difficult to determine the specific cause of this flow but considering (1) the formation of nearby intermediate to rhyolitic dome(s) and synchronous mafic volcanic rocks based on the current understanding of the regional geologic setting (Castonguay et al, 2009;Skulski et al, 2010), (2) volcanic architectural reconstruction of the deposit (Pilote et al, 2015), and (3) the chaotic paleoseafloor topography in this type of environment (Ross and Mercier-Langevin, 2014), collapse of at least part of the marginal domal edifice may have triggered mass flow of volcanic debris. During this process, the sulfide clasts were derived from the underlying (semi-)massive sulfides along its flow path and incorporated into the volcaniclastic unit (Fig.…”

Magmatic evolution and metal systematics of back-arc volcanic rocks of north–east Japan and implications for deposition of massive sulphide Kuroko ores

“…The Hokuroku region of north-eastern Japan is the type locality for "Kuroko" (black ore) type VHMS Zn-Pb-Cu deposits, and has been one of the major mining districts of Japan since its discovery in 1861 (Horikoshi 1990;Ohashi 1920;Tanimura et al 1983), with a total production estimated at 90 Mt of ore (Ross and Mercier-Langevin 2014). Kuroko deposits, with their distinctive association with tuff and lava domes, are the archetype of bimodal-felsic-associated VHMS worldwide and have attracted substantial scientific attention (Ohmoto 1983;Sato 1977).…”