Unraveling the Western Churchill Province Paleoproterozoic Gold Metallotect: Constraints from Re-Os Arsenopyrite and U-Pb Xenotime Geochronology and LA-ICP-MS Arsenopyrite Trace Element Chemistry at the BIF-Hosted Meliadine Gold District, Nunavut, Canada

摘要: The gold endowment of the western Churchill Province is conventionally attributed to reworking and attendant metamorphism during Trans-Hudson Orogeny (1.9–1.8 Ga). Meliadine district regarded as a type example this inferred Paleoproterozoic metallotect also represents one Canada’s largest emerging orogenic greenstone- banded iron formation (BIF)-hosted districts (2.8 Moz contained Au in reserves total resource 5.8 Au). deposits are cospatial with Pyke fault associated quartz (± ankerite) veining, which cuts Neoarchean (ca. 2.66 Ga) plutonic supracrustal rocks comprising Rankin Inlet greenstone belt. Meliadine occurs inclusions within idioblastic arsenopyrite crystals, at sulfide crystal boundaries, and/or fracture fills hydrothermally altered, sulfidized, veined BIF. Clusters gold, Bi-Mo telluride, chalcopyrite, galena characterize high-grade ore zones spatially sieve-textured domains. These microtextural relationships suggest that incipient recrystallization liberated which, along other precious base metals, was redistributed late, fluid-assisted deformation/metamorphic-driven remobilization. Late metal enrichment demonstrated by situ laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) mapping. Hydrothermal xenotime crystals occur low-strain sites yield U-Pb ages ca. 1.86 Ga, suggesting remobilization concomitant Trans Hudson orogenesis. New Re-Os model range from 2.3 1.8 Ga document hitherto unrecognized, pre-1.86 hydrothermal activity. tends support partial open-system behavior mixing disparate generations evident observations LA-ICP-MS element Replicate analyses two most rhenium rich samples reproducible 2.27 1.90 Ga. rhenium-rich poor likely predate subsequent boundaries fractures. We activity critical district, but obscured later stages If correct, these new imply metallotect, recorded across Province, fact comprises multiple, temporally distinct events. Differentiating between events step for effective mineral exploration reworked Archean terranes.