ORCID Profile
0000-0001-6179-4973
Current Organisation
Université Laval
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Publisher: Geological Society of America
Date: 15-03-2017
DOI: 10.1130/G38853.1
Publisher: Society of Economic Geologists, Inc.
Date: 09-2022
DOI: 10.5382/ECONGEO.4923
Abstract: In orogenic gold deposits, the mechanism by which a hydrothermal fluid precipitates gold in laminated quartz veins remains elusive. The Kanowna Belle deposit hosts gold mineralization in structurally controlled quartz-pyrite laminated veins that cut volcano-sedimentary and granitic rocks of the Kalgoorlie terrane, Australia. Veins show microtextural evidence for multiphased emplacement, corresponding to three distinct pyrite growth zones in which Au enrichment in the pyrite is attributed to high fluid influx. To monitor the chemical and isotopic evolution of the auriferous fluid leading to gold precipitation, we combine in situ multiple sulfur isotope analyses with trace element composition of gold-bearing pyrite growth zones: cores (Au ≤149 ppm δ34S –3.3 to +4.2‰ As ≤2.5 wt % Ni ≤4,022 ppm Te ≤416 ppm), Au-rich oscillatory zoned mantles (Au ≤2,251 ppm δ34S –8.4 to +0.1‰ As ≤4.5 wt % Ni ≤1,111 ppm Te ≤829 ppm), and rims (Au ≤264 ppm δ34S –6.0 to +2.8‰ As ≤1.4 wt % Ni ≤2,113 ppm Te ≤229 ppm). The positive and consistent Δ33S of each zone (Δ33S = +0.3 ± 0.2‰ n = 160) indicates that one single reservoir was tapped during the evolution of the mineralizing system. The gold-rich pyrite mantle zones precipitated from a fluid undergoing SO42−/H2S fluctuations associated with phase separation due to rapid and repeated releases in fluid pressure. This study demonstrates that the “fault-valve” process applies a first-order control on the precipitation of gold from a single auriferous fluid reservoir.
Publisher: Elsevier BV
Date: 07-2016
Publisher: Springer Science and Business Media LLC
Date: 28-02-2020
Publisher: Springer Science and Business Media LLC
Date: 22-10-2018
DOI: 10.1038/S41467-018-06691-3
Abstract: The sulfur cycle across the lithosphere and the role of this volatile element in the metasomatism of the mantle at ancient cratonic boundaries are poorly constrained. We address these knowledge gaps by tracking the journey of sulfur in the assembly of a Proterozoic supercontinent using mass independent isotope fractionation (MIF-S) as an indelible tracer. MIF-S is a signature that was imparted to supracrustal sulfur reservoirs before the ~2.4 Ga Great Oxidation Event. The spatial representation of multiple sulfur isotope data indicates that successive Proterozoic granitoid suites preserve Δ 33 S up to +0.8‰ in areas adjacent to Archean cratons. These results indicate that suturing of cratons began with devolatilisation of slab-derived sediments deep in the lithosphere. This process transferred atmospheric sulfur to a mantle source reservoir, which was tapped intermittently for over 300 million years of magmatism. Our work tracks pathways and storage of sulfur in the lithosphere at craton margins.
Publisher: Elsevier BV
Date: 06-2018
Publisher: University of New Brunswick Libraries - UNB
Date: 29-07-2015
DOI: 10.12789/GEOCANJ.2015.42.065
Abstract: SUMMARYThe Repulse Bay block (RBb) of the southern Melville Peninsula, Nunavut, lies within the Rae craton and exposes a large (50,000 km2) area of middle to lower crust. The block is composed of ca. 2.86 Ga and 2.73–2.71 Ga tonalite-trondhjemite-granodiorite (TTG) and granitic gneiss that was derived from an older 3.25 and 3.10 Ga crustal substrate. This period of crustal generation was followed by the emplacement of ca. 2.69–2.66 Ga enderbite, charnockite, and granitoid intrusions with entrained websterite xenoliths. These voluminous batholith-scale bodies (dehydrated and hydrated intrusions), and the associated websterite xenoliths, have similar whole rock geochemical properties, including fractionated light rare earth element (LREE)–heavy (H)REE whole rock patterns and negative Nb, Ti, and Ta anomalies. Dehydrated intrusions and websterite xenoliths also contain similar mineralogy (two pyroxene, biotite, interstitial hibole) and similar pyroxene trace element compositions. Based on geochemical and mineralogical properties, the two lithologies are interpreted to be related by fractional crystallization, and to be the product of a magmatic cumulate processes. Reworking of the crust in a ca. 2.72 Ga subduction zone setting was followed by ca. 2.69 Ga upwelling of the asthenospheric mantle and the intrusion of massif-type granitoid plutons. Based on a dramatic increase in FeO, Zr, Hf, and LREE content of the most evolved granitoid components from the 2.69–2.66 Ga cumulate intrusion, we propose that those granitoid plutons were in part derived from a metasomatized mantle source enriched by fluids from the subducting oceanic slab that underwent further hybridization (via assimilation) with the crust. Large-scale, mantle-derived Neoarchean sanukitoid-type magmatism played a role in the development of a depleted lower crust and residual sub-continental lithospheric mantle, a crucial element in the preservation of the RBb.RÉSUMÉLe bloc de Repulse Bay (RBb) dans le sud de la péninsule de Melville, au Nunavut, est situé dans le craton de Rae et expose une large zone (50 000 km2) de croûte moyenne à inférieur. Ce bloc est composé de tonalite-trondhjémite-granodiorite (TTG) daté à ca. 2,86 Ga et 2,73–2,71 Ga, et de gneiss granitique dérivé d’un substrat crustal plus ancien daté à 3,25 Ga et 3,10 Ga. Cette période de croissance crustale a été suivie par la mise en place entre ca. 2,69 et 2,66 Ga d’intrusions d’enderbite, charnockite et de granitoïde incluant des xénolites d’entraînement de websterite. Ces intrusions de taille batholitique (intrusions déshydratées et hydratées) ainsi que les xénolites d’entraînement de websterite associés, ont des propriétés géochimiques sur roche totale semblables notamment leurs profils de fractionnement des terres rares légers (LREE) et des terres rares lourds (HREE) ainsi que leurs anomalies négatives en Nb, Ti et Ta. Les intrusions déshydratées et les xénolites de websterite ont aussi des minéralogies similaires (deux pyroxènes, biotite, hibole interstitielle) ainsi que des compositions semblables en éléments traces de leurs pyroxènes. Étant donné leurs propriétés géochimiques et minéralogiques, ces deux lithologies sont interprétées comme provenant d’une cristallisation fractionnée, et comme étant le produit de processus d'accumulations magmatiques. Le remaniement de la croûte dans un contexte de subduction vers ca. 2,72 Ga, a été suivi vers ca. 2,69 Ga d’une remontée du manteau asthénosphérique et de l’intrusion de granitoïdes de type massif. D'après l’importante augmentation en FeO, Zr, Hf et LREE dans les granitoïdes les plus évolués du magmatisme ayant pris place entre ca. 2,69 Ga et 2,66 Ga, nous proposons que ces plutons aient été en partie dérivés d’une source mantélique métasomatisée enrichies par des fluides d’une plaque océanique en subduction et qui a subi une hybridation supplémentaire (par assimilation) avec la croûte. Le magmatisme néo-archéen de type sanukitoïde, dérivé du manteau et de grande échelle, a joué un rôle dans le développement d’une croûte inférieure et d’un manteau lithosphérique continental résiduel appauvri, un élément déterminant pour la préservation du RBb.
Publisher: Elsevier BV
Date: 06-2018
Publisher: Elsevier BV
Date: 07-2020
Publisher: Springer Science and Business Media LLC
Date: 30-05-2019
Publisher: Elsevier BV
Date: 02-2021
Publisher: Geological Society of America
Date: 19-05-2017
DOI: 10.1130/G39018.1
Publisher: Elsevier BV
Date: 02-2018
Publisher: Springer Science and Business Media LLC
Date: 10-06-2020
Publisher: Elsevier BV
Date: 02-2020
Publisher: Springer Science and Business Media LLC
Date: 18-09-2018
Publisher: Elsevier BV
Date: 02-2018
Publisher: Elsevier BV
Date: 10-2017
Publisher: Springer Science and Business Media LLC
Date: 11-02-2017
Publisher: Springer Science and Business Media LLC
Date: 05-01-2021
Publisher: Elsevier BV
Date: 04-2017
Publisher: Copernicus GmbH
Date: 24-06-2020
Abstract: Abstract. Gravity and 3D modelling combined with geochemical analysis examine the subsurface within and below the poorly exposed Palaeoproterozoic Yerrida Basin in central Western Australia. Understanding the structure of a region is important as key features indicating past geodynamic processes and tectonic activity can be revealed. However, in stable, post-depositional tectonic settings only the younger sedimentary units tend to be widely exposed, rendering direct observation of basement and intrusive rocks impossible. Geophysical imaging and modelling can reveal the structure of a region undercover. High-magnitude density anomalies around the basin cannot be reconciled with current geological knowledge in the case presented here. The gravity anomalies infer an abundance of buried and high-density material not indicated by the surface geology. A hypothetical causative source for the high-magnitude gravity anomalies is mafic rocks that were intruded and extruded during basin rifting. The simplest and plausible stratigraphic attribution of these interpreted mafic rocks is to the Killara Formation within the Mooloogool Group. However, geochemistry reveals that the Killara Formation is not the only host to mafic rocks within the region. The mafic rocks present in the Juderina Formation are largely ignored in descriptions of Yerrida Basin magmatism, and results indicate that they may be far more substantial than once thought. Sulfur isotopic data indicate no Archean signature to these mafic rocks, a somewhat surprising result given the basement to the basin is the Archean Yilgarn Craton. We propose the source of mafic rocks is vents located to the north along the Goodin Fault or under the Bryah sub-basin and Padbury Basin. The conclusion is that the formation of the Yerrida Basin involves a geodynamic history more complex than previously thought. This result highlights the value in geophysics and geochemistry in revealing the complexity of the earlier geodynamic evolution of the basin that may be indiscernible from surface geology but may have high importance for the tectonic development of the region and its mineral resources.
Publisher: Springer Science and Business Media LLC
Date: 02-2018
Publisher: Elsevier BV
Date: 12-2016
Publisher: Elsevier BV
Date: 03-2018
Publisher: American Geophysical Union (AGU)
Date: 08-2018
DOI: 10.1029/2018GC007499
Publisher: Elsevier BV
Date: 11-2021
Publisher: Elsevier BV
Date: 10-2018
No related grants have been discovered for Crystal LaFlamme.