ORCID Profile
0000-0002-9432-9880
Current Organisation
University of Tasmania
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Publisher: Public Library of Science (PLoS)
Date: 07-2020
Publisher: Society of Economic Geologists
Date: 22-05-2015
Publisher: Elsevier BV
Date: 07-2013
Publisher: Elsevier BV
Date: 2020
Publisher: Elsevier BV
Date: 09-09-2005
Publisher: Society of Economic Geologists
Date: 02-05-2013
Publisher: Elsevier BV
Date: 10-2020
Publisher: Society of Economic Geologists
Date: 08-2020
DOI: 10.5382/ECONGEO.4723
Abstract: The use of hyperspectral reflectance in mineral exploration has been steadily increasing in recent decades. This study presents a novel approach that integrates geochemical and spectral proxies to delineate ore formation and alteration processes, which provide new spectral-based exploration parameters that can be used in real time. The precious metal-bearing, bimodal-felsic Northwest zone of the Lemarchant volcanogenic massive sulfide (VMS) deposits, Newfoundland, Canada, is used as a case study. Alteration associated with the Northwest zone includes intense and localized sulfide (pyrite, chalcopyrite, sphalerite, and galena) and barite enrichment, as well as quartz, white mica, and chlorite alteration. Zones of elevated Zn (& ,000 ppm) are associated with high chlorite carbonate pyrite index (CCPI), Ishikawa alteration index (AI), Ba/Sr, and low Na2O values and elevated SiO2 and K2O, Fe2O3, Na2O, and BaO contents, similar to global alteration signatures in VMS deposits. Mineralized areas contain phengitic white micas with 2,200-nm absorption features longer than 2,215 nm and Mg-rich chlorites with 2,250-nm absorption features shorter than 2,252 nm. Together, these data are consistent with the Northwest zone having undergone intense hydrothermal alteration during the mineralization event. A new lithology-normalized spectral alteration index (SAI) for white mica and chlorite was developed in order to map and characterize the alteration intensity surrounding the deposit. In addition, depth ratio parameters (2200D/2340D vs. 2250D/2340D) were used to characterize mineralogical changes and zonation. Together, these features document a paleofluid pathway with Mg chlorite alteration extending to at least 300 m away from the mineralization, outside the study area, within the andesitic and dacitic units. The use of hyperspectral reflectance coupled with geochemical alteration proxies permitted the identification of areas of intense alteration, the chemical affinities of the minerals, and their relationships to alteration processes (i.e., seawater alteration versus silicification), which would not be possible using geochemistry alone.
Publisher: MDPI AG
Date: 30-04-2021
DOI: 10.3390/MIN11050471
Abstract: Hyperspectral reflectance has the potential to provide rapid and low-cost mineralogical and chemical information that can be used to vector in mineral systems. However, the spectral signature of white mica and chlorite, despite numerous studies, is not fully understood. In this study, we review the mineralogy and chemistry of different white mica and chlorite types and investigate what mineralogical and chemical changes are responsible for the apparent shifts in the shortwave infrared (SWIR) spectroscopic absorption features. We demonstrate that the spectral signature of white mica is more complex than previously documented and is influenced by the Tschermak substitution, as well as the sum of interlayer cations. We show that an increase in the interlayer deficiencies towards illite is associated with a change from steep to shallow slopes between the wavelength position of the 2200 nm feature (2200 W) and Mg, Al(VI) and Si. These changes in slope imply that white micas with different elemental chemistry may be associated with the same 2200 W values and vice versa, contrary to traditional interpretation. We recommend that traditional interpretations should only be used in true white mica with sum interlayer cations (I) 0.95. The spectral signature of trioctahedral chlorite (clinochlore, sheridanite, chamosite and ripidolite) record similar spectral relationships to those observed in previous studies. However, dioctahedral Al-rich chlorite (sudoite, cookeite and donbassite) has a different spectral response with Mg increasing with 2250 W, which is the opposite of traditional trioctahedral chlorite spectral interpretation. In addition, it was shown that dioctahedral chlorite has a 2200 W absorption feature that may introduce erroneous spectral interpretations of white mica and chlorite mixtures. Therefore, care should be used when interpreting the spectral signature of chlorite. We recommend that spectral studies should be complemented with electron microprobe analyses on a subset of at least 30 s les to identify the type of muscovite and chlorite. This will allow the sum I of white mica to be obtained, as well as estimate the slope of 2200 W absorption trends with Mg, Al(vi), and Si. Preliminary probe data will allow more accurate spectral interpretations and allow the user to understand the limitations in their hyperspectral datasets.
Publisher: Elsevier BV
Date: 10-2023
Publisher: Elsevier BV
Date: 04-2017
Publisher: Elsevier BV
Date: 10-2020
Publisher: Society of Economic Geologists
Date: 09-2009
Publisher: Springer Science and Business Media LLC
Date: 30-11-2020
DOI: 10.1186/S12889-020-09906-9
Abstract: This study examined the relationship between male out-migration and family planning (FP) behaviour of women in rural Bihar. Data was collected from 937 currently married women aged 15–34 years from two districts of Bihar, namely Nawada and Gopalganj. Respondents were selected through a multi-stage systematic s ling and were recruited from both low and high male out-migration blocks. Differences in FP outcomes—use of modern contraceptive methods, intention to use contraceptives in next 12 months and access to FP services—were assessed by volume of migration, husband’s migration status, frequency of return, and duration of husband’s stay at home during visits. Women with migrant husbands were about 50% less likely to use modern contraceptive methods. Further, the odds of using modern contraceptives was about half among women with migrant husbands if they resided in high out-migration areas (HMA) than low out-migration areas (LMA) (15% vs 29%, AOR: 0·50, p = 0·017). A higher proportion of women with migrant husbands, specifically from HMA, reported greater intention of using contraceptives in next 12 months than their counterparts (37% vs 23%, AOR: 1·83, p = 0·015). Similarly, access to FP services was negatively associated with the volume of male out-migration, specifically for women with migrant husbands. The migratory environment as well as the migration of husbands affect contraceptive use and access to FP services among women. Given that a significant proportion of married males leave their home states for work, it is imperative that FP programs in migration affected areas plan and implement migration-centric FP implementation strategies.
Publisher: Springer Science and Business Media LLC
Date: 09-2010
Publisher: Society of Economic Geologists
Date: 03-2010
Publisher: Geological Society of London
Date: 11-07-2017
DOI: 10.1144/JGS2017-008
Publisher: Elsevier BV
Date: 09-2020
Publisher: Geological Society of America
Date: 03-12-2021
DOI: 10.1130/G49471.1
Abstract: Alkaline igneous rocks host many global high-field-strength element (HFSE) and rare-earth element (REE) deposits. While HFSEs are commonly assumed to be immobile in hydrothermal systems, transport by late-stage hydrothermal fluids associated with alkaline magmas is reported. However, the magnitude of the flux and the conditions are poorly constrained and yet essential to understanding the formation of REE-HFSE ores. We examined the alteration of country rocks (“fenitization”) accompanying the emplacement of a syenite magma at Illerfissalik in Greenland, through analysis of changes in rock chemistry, mineralogy, and texture. Our novel geochemical maps show a 400-m-wide intrusion aureole, within which we observed typically tenfold increases in the concentrations of many elements, including HFSEs. Textures suggest both pervasive and structurally hosted fluid flow, with initial reaction occurring with the protolith's quartz cement, leading to increased permeability and enhancing chemical interaction with a mixed Ca-K-Na fenitizing fluid. We estimated the HFSE masses transferred from the syenite to the fenite by this fluid and found ~43 Mt of REEs were mobilized (~12% of the syenite-fenite system total rare-earth-oxide [TREO] budget), a mass comparable to the tonnages of some of the world's largest HFSE resources. We argue that fenite can yield crucial information about the tipping points in magma evolution because retention and/or loss of volatile-bonded alkali and HFSEs are key factors in the development of magmatic zirconosilicate-hosted HFSE ores (e.g., Kringlerne, at Ilímaussaq), or the formation of the syenite-hosted Nb-Ta-REE (Motzfeldt-type) roof-zone deposits.
Publisher: Springer Science and Business Media LLC
Date: 12-04-2016
Location: United Kingdom of Great Britain and Northern Ireland
No related grants have been discovered for Jonathan Cloutier.