Contrasting arc and MORB-like assemblages in the Paleoproterozoic Flin Flon Belt, Manitoba, and the role of intra-arc extension in localizing volcanic-hosted massive sulphide deposits

Abstract

The Flin Flon Belt (Trans-Hudson Orogen, Manitoba and Saskatchewan) is the largest Paleoproterozoic volcanic-hosted massive sulphide (VMS) district in the world, with 118.7 million tonnes (Mt) of Zn-Cu-(Au-Ag) sulphide ore in 25 past or presently producing mines and 64.3 Mt in subeconomic deposits. The orebodies are restricted to isotopically juvenile volcanic-arc sequences, dated at 1.903-1.881 Ga at Flin Flon. Sequences of ca. 1.904-1.901 Ga back-arc and ocean-plateau basalts and related plutonic rocks, structurally juxtaposed with the arc assemblages at 1.880-1.870 Ga, are not known to contain economic base metal deposits. The juvenile arc tectonostratigraphic assemblages are generally marked by older and stratigraphically lower tholeiitic submarine volcanic packages (ca. 1.903-1.886 Ga) that are observed or interpreted to be overlain by extensive and lithologically varied sequences of calc-alkaline and alkaline (shoshonitic) arc rocks and arc rift deposits (ca. 1.888-1.881 Ga). VMS deposits occur in both the tholeiitic and calc-alkaline arc sequences, but the 62 Mt Flin Flon deposit occurs in a 1.903 Ga tholeiitic primitive arc package. It can be demonstrated that for the Flin Flon -Callinan -Triple 7, Cuprus, and White Lake VMS deposits, whose stratigraphic context is preserved, deposition of the massive sulphides was temporally associated with inferred arc rifting processes. Critical observations for arc rifting include evidence for extensional faulting, erosion, and development of unconformities; extrusion of MORB-like basalts and associated rhyolites; and development of depositional basins with thick sequences of shoshonitic turbidites. As has been proposed for other major VMS camps (e.g., Kuroko, Kidd Creek, Bathurst), arc rifting can generate the loci of sustained high heat flow and fluid pathways required for the development of long-lived hydrothermal convection systems.Résumé : La Zone de Flin Flon (de l'orogène trans-hudsonien, au Manitoba et en Saskatchewan) représente le plus grand district de sulfures massifs associés à des roches volcaniques dans le monde, avec 118,7 millions de tonnes (Mt) de minerai sulfuré de Zn-Cu-(Au-Ag) dans les 25 gisements actuellement ou antérieurement en production, auxquels on doit ajouter 64,3 MT dans des gîtes à teneur subéconomique. Les corps minéralisés sont restreints aux séquences d'arc volcanique isotopiquement juvéniles qui sont datées de 1,903-1,881 Ga à Flin Flon. On n'a pas réussi à trouver des gîtes de métaux communs à teneur économique dans les séquences d'arrière-arc âgées approximativement de 1,904-1,901 Ga, et ni dans les basaltes de plateau océaniques ou dans les roches plutoniques associées qui sont structuralement juxtaposées aux assemblages d'arc âgés de 1,880-1,870 Ga. Dans les assemblages tectonostratigraphiques d'arc juvénile, apparaissent généralement des lots de roches volcaniques tholéiitiques plus anciennes (environ 1,903-1,886 Ga) d'origine sous-marine à un niveau stratigraphique inférieur; ces lots sont observés ou interprétés comme étant r...

Geochemistry, petrogenesis and tectonic setting of Neoproterozoic mafic–ultramafic rocks from the western Jiangnan orogen, South China

“…8) to MORB-BABB (Fig. 15), which is commensurate with the consequences of intra-arc extension (Syme et al, 1999). In addition, the coeval rhyodacite (765 ± 14 Ma, cf., Zhou et al, 2007a) is interbedded with the DZG basaltic rocks, constituting a bimodal volcanic assemblage, which is consistent with those in the intra-arc basin of the Flin Flon Belt of the Superior Craton (Syme et al, 1999).…”

“…The basaltic rocks of the Danzhou Group show the dual features of MORB-and arc-like chemistry, which are commonly inferred to be formed in a fore-arc (Reagan et al, 2010;Morishita et al, 2011), or back-arc (Gribble et al, 1998;Shuto et al, 2006;Teklay, 2006;Thanh et al, 2014), or intra-arc basin (Syme et al, 1999), or some other extensional environment. What is more, the sedimentary facies features reflect that the Danzhou Group and its equivalents are representative of extension-related sedimentary sequences Zhang et al, 2009b;Zhao et al, 2011;Wang and Zhou, 2012).…”

Accretionary orogens through Earth history

“…Styles of Archaean and Proterozoic mineralization resemble Phanerozoic deposits related to subduction environments (Sawkins 1990;Kerrich et al 2005), including a Palaeoarchaean porphyry Cu deposit (Barley 1992) and Archaean and Palaeoproterozoic volcanogenic massive sulphide Cu -Zn deposits (Barley 1992;Allen et al 1996;Syme et al 1999;Wyman et al 1999a, b). Condie & Kröner (2008) listed several distinctive petrotectonic assemblages such as accretionary prisms as well as arc-back-arc-forearc associations that argue for the existence of accretionary orogens since the early Archaean.…”

Integrated 3D Geological Modeling to Gain Insight in the Effects of Hydrothermal Alteration on Post-Ore Deformation Style and Strain Localization in the Flin Flon Volcanogenic Massive Sulfide Ore System

“…The 2D map pattern of NE-SW and N-S trending faults splays was previously interpreted to result from a single event of thrust faulting [23,[53][54][55]. The tightly-constrained 3D models of these faults, however, show that two distinct intersecting sets of relatively planar thrust faults are required to accommodate, in addition to the 500 m displacement of the ore horizon in westerly direction, 165-400 m of displacement of the Millrock member and the ore lenses hosted within it in a northerly direction, consistent with kinematic analysis of the D 4 faults in underground mine workings [15].…”