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Title3-D visualization of multi-phase hydrothermal flow, silicification, and hydration: Architecture of the Horne hydrothermal system, Rouyn-Noranda
AuthorTaylor, B; de Kemp, E; Grunsky, E; Martin, L; Goutier, J; Lauzière, K; Dubé, B; Rigg, D
SourceGeological Association of Canada-Mineralogical Association of Canada, Joint Annual Meeting, Programs with Abstracts vol. 34, 2011 p. 214-215
LinksOnline - En ligne
Alt SeriesEarth Sciences Sector, Contribution Series 20130575
Mediapaper; on-line; digital
File formatpdf
NTS32D/02; 32D/03; 32D/06; 32D/07
Lat/Long WENS-79.2500 -78.7500 48.3333 48.1667
Subjectseconomic geology; igneous rocks; volcanic rocks; plutonic rocks; mineral occurrences; volcanogenic deposits; mineral deposits; gold; copper; mineralization; sulphides; sulphide deposits; hydrothermal alteration; Horne Deposit; Noranda Volcanic Complex; Precambrian; Proterozoic
ProgramTargeted Geoscience Initiative (TGI-4), Gold Ore Systems
AbstractInterpolated whole-rock oxygen isotope compositions, Si/Al ratios, and H2O (wt. %) of outcrop and drill core samples yield 2D and 3D patterns that describe the architecture of the hydrothermal system responsible for the world-class Horne VMS deposit. Estimations respected the Horne Creek and Andesite faults bounding the 'Horne block', and other regional faults in adjacent areas. d18OWR values of 132 outcrop samples within ca. 5km of the Horne mine vary systematically 2.8 to 12.4perthousand with alteration mineral assemblage; fresh rocks have d18OWR d 6.0 (andesite) to 8.0perthousand (rhyolite). 182 samples of drill core in the Horne block and Horne mine yielded d18OWR from 3.8 to 11.0perthousand. Si/Al ratios from 4845 screened samples vary from 1.2 to 19.7 in both mafic and felsic rocks; wt.% H2O varies from 0.02 to 4.03 in mafic rocks, and from 0.02 to 2.14 in felsic rocks. Values of d18OWR <6 and >9perthousand were chosen to denote high- and low-temperature alteration, respectively; values of Si/Al <3.2 and >4.8 (mafic rocks), and <4.0 and >7.0 (felsic rocks), denote de-silicified and silicified rocks, respectively. Values of wt.% H2O were kriged to yield gradient maps. High- to low-temperature, eastward directed flow paths, including a discordant, low d18O (high-temperature) zone emanating from the Powell Pluton associated with elevated Cu/(Cu+Zn) ratios, mark several, successive hydrothermal episodes. Where not overprinted by younger alteration, silicified rocks (especially andesites) occur downstream, associated with zones of higher d18OWR. Within the Horne block, isotopic data indicate at least two periods of hydrothermal activity. High-temperature upflow in the Horne footwall occurred between the Upper H and Lower H orebodies, and near the termination of the Lower H, possibly along previously identified synvolcanic faults. Silicification of a broad, concordant zone beneath the Upper and Lower H orebodies, down to ca. 4000', is coincident with discordant and concordant zones of high d18O rocks, and suggests fluid mixing during protracted cooling led to silicification and mineralization. High-temperature alteration in the hanging wall records subsequent hydrothermal activity. Whereas, zones of silicification may be associated with isotopically mapped thermal gradients and hydrothermal flow paths, maps of hydration are less clear, although, some high-temperature (chloritization) and low-temperature (sericitization) reaction zones do correspond with analogous, oxygen-isotope mapped zones. The nature and architecture of the hydrothermal system may have played a key role in the size of the deposit. Higher resolution structural models may further enhance the potential for depth predictability of new resources.