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dc.contributor.authorMontgomery, Allan Trevoren
dc.date2012-03-30 13:15:08.424
dc.date2012-04-05 11:09:14.751
dc.date.accessioned2012-04-05T15:15:38Z
dc.date.available2012-04-05T15:15:38Z
dc.date.issued2012-04-05
dc.identifier.urihttp://hdl.handle.net/1974/7047
dc.descriptionThesis (Ph.D, Geological Sciences & Geological Engineering) -- Queen's University, 2012-04-05 11:09:14.751en
dc.description.abstractThe Alto Chicama district, Central Andean Cordillera Occidental, La Libertad, northern Perú, hosts the 14 M oz, Miocene Lagunas Norte high-sulphidation epithermal Au-(Ag) deposit (Latitude 7° 56ʹ30ʺ S; Longitude 78°14ʹ50ʺ W), in addition to several important, epithermal and mesothermal precious ± base-metal vein systems and porphyry Cu-Au-(Mo) deposits and prospects. The district is underlain by lower Oligocene-to-Middle Miocene, subaerial, Calipuy Supergroup volcanic rocks, unconformably overlying Upper Jurassic – Lower Cretaceous marine sedimentary strata affected by late Eocene-early Oligocene thin-skinned fold and thrust deformation. Mineralization at Lagunas Norte is largely hosted by intensely-folded Valanginian Chimú Formation quartz arenite, but extends into overlying, weakly-deformed, Lower Miocene dacitic volcaniclastic deposits. Fold- and thrust-related deformation at the deposit, and subsequent magmatic and hydrothermal activity, were localized along a long-lived, crustal-scale cross-strike discontinuity. Hydrothermal activity at Lagunas Norte was associated with local extension within an overall regional compressive regime. Ore formation occurred during the terminal stages of andesitic-to-dacitic magmatism in the deposit area, immediately following the sector collapse of an adjacent volcanic centre, and during eruption of late-stage peripheral dacitic domes. Intense advanced-argillic alteration occurred in at least two major pulses over a ~ 0.9 m.y. period, implying repeated magma influx in a shallow subjacent chamber. The ensuing Au-(Ag)-pyrite-enargite deposition resulted from mixing of magmatic vapour with oxidized groundwaters, a process stimulated by the contiguous incision of a steep-walled valley-pediment. The local volcanic rocks record a transition from “normal arc” to higher-pressure “adakitic” magmatism, initiated during ore deposition at Lagunas Norte, but exhibited by the entire Calipuy arc in northern Perú, and interpreted to reflect the destabilization of plagioclase and stabilization of garnet in inferred lower-crustal magmas. The progressive depletion of 18O and D in meteoric water recorded in late Oligocene-to-Late Miocene hypogene and supergene minerals is in permissive agreement with major uplift from ~ 1000 m to over 3000 m a.s.l. during hydrothermal activity. Hydrothermal activity and related ore deposition at Lagunas Norte unambiguously predated, by at least 2 m.y., the impingement of the aseismic Nazca Ridge at the Perú Trench and the ensuing flattening of the subducting slaben
dc.language.isoengen
dc.relation.ispartofseriesCanadian thesesen
dc.rightsThis publication is made available by the authority of the copyright owner solely for the purpose of private study and research and may not be copied or reproduced except as permitted by the copyright laws without written authority from the copyright owner.en
dc.subjectEpithermalen
dc.subjectGolden
dc.subjectHigh-Sulphidationen
dc.subjectPeruen
dc.subjectMioceneen
dc.subjectMetallogenyen
dc.subjectGeochronologyen
dc.subjectPetrogenesisen
dc.subjectPaleoaltimetryen
dc.titleMetallogenetic Controls on Miocene High-Sulphidation Epithermal Gold Mineralization, Alto Chicama District, La Libertad, Northern Perúen
dc.typethesisen
dc.description.degreePhDen
dc.contributor.supervisorClark, Alan H.en
dc.contributor.supervisorKyser, T. Kurtisen
dc.contributor.supervisorLee, Jamesen
dc.contributor.departmentGeological Sciences and Geological Engineeringen
dc.degree.grantorQueen's University at Kingstonen


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