ORCID Profile
0000-0002-9886-8793
Current Organisations
Lakehead University
,
University of Saskatchewan
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Publisher: Elsevier BV
Date: 2017
Publisher: Elsevier BV
Date: 09-2016
Publisher: Elsevier BV
Date: 04-2016
Publisher: Society of Economic Geologists
Date: 2012
Publisher: Oxford University Press (OUP)
Date: 06-1994
Publisher: Society of Economic Geologists
Date: 03-04-2017
Publisher: Society of Economic Geologists
Date: 17-11-2011
Publisher: Elsevier BV
Date: 10-2016
Publisher: Elsevier BV
Date: 2017
Publisher: Springer Science and Business Media LLC
Date: 16-04-2020
Publisher: Society of Economic Geologists
Date: 17-11-2011
Publisher: Elsevier BV
Date: 11-2016
Publisher: Springer Science and Business Media LLC
Date: 28-05-2019
Publisher: Elsevier BV
Date: 06-2017
Publisher: Mineralogical Society of America
Date: 06-2020
DOI: 10.2138/AM-2020-7194
Abstract: Scheelite from the Tongshankou porphyry-skarn Cu-Mo(-W) deposit occurs mainly as disseminated grains in the altered granodiorite porphyries at depth (Sch A), in the skarn coeval with retrograde alteration (Sch B) and in distal quartz veins crosscutting marbles (Sch C). Cathodoluminescence (CL) responses within a single Sch A grain reveal two subtypes: CL-clear Sch A-I and CL-turbid, densely veined Sch A-II. The CL contrast, coupled with geochemical data, suggest Sch A-I was metasomatized to form Sch A-II. CL images reveal that Sch A-I, Sch B and Sch C are all homogenous, with blue luminescence and are depleted in heavy rare earth elements (HREE), indicating a primary origin. However, Sch A-II is characterized by higher contents of light REE and heavy REE as well as higher Sr isotopes (0.7080–0.7100) than the primary scheelite (& .7080). These differences indicate that Sch A-II formed through dissolution-reprecipitation. The Sr isotopes of the primary scheelite (0.7073–0.7078) are generally consistent with those of the mineralized granodiorite porphyries (0.7061–0.7063) and mafic enclaves (0.7058–0.7073). The granodiorite porphyries contain low tungsten contents (3–11 ppm), whereas high tungsten contents were detected in mafic enclaves (48–75 ppm). The coexistence of mafic enclaves and tungsten mineralization at depth, and their consistent Sr isotopes, indicates that the interaction of mafic enclaves and exsolved magmatic fluids from the granodiorite porphyries may have played an important role in the extraction of tungsten from the mafic enclaves and formation of scheelite mineralization. Our work shows that scheelite geochemistry can be used to trace the mineralizing conditions but the compositions may be significantly modified during the ore-forming process. Thus, detailed textural relationships should be investigated before using scheelite geochemistry to constrain the hydrothermal fluids and ore genesis.
Publisher: Society of Economic Geologists
Date: 17-11-2011
Publisher: Oxford University Press (OUP)
Date: 05-2018
Publisher: Elsevier BV
Date: 03-2016
Publisher: Geological Society of London
Date: 12-02-2020
Publisher: Society of Economic Geologists
Date: 2018
Publisher: Elsevier BV
Date: 02-2020
Publisher: Society of Economic Geologists
Date: 06-2020
DOI: 10.5382/ECONGEO.4735
Abstract: The giant, high-grade Resolution porphyry Cu-Mo deposit in the Superior district of Arizona is hosted in Proterozoic and Paleozoic basement and in an overlying Cretaceous volcaniclastic breccia and sandstone package. Resolution has a central domain of potassic alteration that extends more than 1 km outboard of the ore zone, overlapping with a propylitic halo characterized by epidote, chlorite, and pyrite that is particularly well developed in the Laramide volcaniclastic rocks and Proterozoic dolerite sills. The potassic and propylitic assemblages were overprinted in the upper parts of the deposit by intense phyllic and advanced argillic alteration. The district was disrupted by Tertiary Basin and Range extension, and the fault block containing Resolution and its Cretaceous host succession was buried under thick mid-Miocene dacitic volcanic cover, obscuring the geologic, geophysical, and geochemical footprint of the deposit. To test the potential of propylitic mineral chemistry analyses to aid in the detection of concealed porphyry deposits, a blind test was conducted using a suite of epidote-chlorite ± pyrite-altered Laramide volcaniclastic rocks and Proterozoic dolerites collected from the propylitic halo, with s les taken from two domains located to the north and south and above the Resolution ore zone. Laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) data of epidote provided indications of deposit fertility and proximity. Competition for chalcophile elements (As, Sb, Pb) between coexisting pyrite and epidote grains led to a subdued As-Sb fertility response in epidote, consistent with epidote collected between 0.7 and 1.5 km from the center of a large porphyry deposit. Temperature-sensitive trace elements in chlorite provided coherent spatial zonation patterns, implying a heat source centered at depth between the two s le clusters, and application of chlorite proximitor calculations based on LA-ICP-MS analyses provided a precisely defined drill target in this location in three dimensions. Drilling of this target would have resulted in the discovery of Resolution, confirming that epidote and chlorite mineral chemistry can potentially add value to porphyry exploration under cover.
Publisher: Elsevier BV
Date: 05-2016
Publisher: Society of Economic Geologists
Date: 2018
Publisher: Society of Economic Geologists
Date: 08-2005
Publisher: Society of Economic Geologists, Inc.
Date: 08-2013
DOI: 10.2113/ECONGEO.108.5.1147
Abstract: Halloysite, a phyllosilicate clay mineral chemically similar to but structurally different from kaolinite, occurs in a variety of mineral deposit types. It is, however, difficult to identify and dehydrates quite readily. When identified in a porphyry or epithermal environment, halloysite is often interpreted to be a low-temperature polymorph of kaolinite and an indication of supergene processes. The occurrence of halloysite in the Cerro la Mina Au (Cu-Mo) prospect, Chiapas, Mexico, was investigated to determine if halloysite in porphyry-epithermal deposits might also be the product of hypogene processes. The prospect consists of Quaternary volcaniclastic breccias intruded by monzodiorites and trachyandesites crosscut by a volcanic-hydrothermal breccia pipe. Gold-copper-molybdenum mineralization at Cerro la Mina is structurally and lithologically controlled by matrix-rich breccia pipes hosting all of the significant alteration and mineralization drilled to date. Average grades within the prospect are 0.4 ppm Au, 0.16% Cu, and 131 ppm Mo. A total of 100 s les were obtained from 22 diamond drill holes over a range of stratigraphic levels. X-ray diffraction (XRD) and SWIR techniques were employed to identify the different clay minerals found within these s les, including halloysite, kaolinite, dickite, and illite. Identification of halloysite and kaolinite were facilitated by the use of formamide intercalation to produce distinctive peaks for the two minerals in X-ray diffractograms. Halloysite and kaolinite were found to occur from the current erosional surface to depths of over 800 m. Halloysite occurs as both the hydrated 10Å and dehydrated 7Å forms within the deposit. The morphology of the halloysite present is that of well-developed tubes and spheroids. Results of the study show that halloysite associated with gypsum and jarosite is of supergene origin, whereas halloysite occurring with quartz, alunite, dickite, kaolinite, and pyrite is of hypogene origin.
Publisher: Society of Economic Geologists
Date: 08-2005
Publisher: Elsevier BV
Date: 2016
Publisher: Society of Economic Geologists
Date: 08-2005
Publisher: Mineralogical Society of America
Date: 03-2019
DOI: 10.2138/AM-2019-6609
Publisher: Springer Science and Business Media LLC
Date: 09-2003
Publisher: Elsevier
Date: 2014
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Pete Hollings.