Publications
157 results found
Parnel J, Earls G, Wilkinson JJ, et al., 2000, Regional fluid flow and gold mineralization in the Dalradianof the Sperrin Mountains, Northern Ireland, Economic Geology, Vol: 95, Pages: 1389-1416, ISSN: 0361-0128
Gold vein mineralization occurs in the metamorphosed and deformed Dalradian (Neoproterozoic) rocks of the Sperrin Mountains, Northern Ireland. Two structures exerted a control on the location of the mineralization; the north-south Omagh lineament and the west-northwest-east-southeast Curraghinalt lateral ramp in the footwall of the northeast-southwest Omagh thrust. These are Caledonian structures resulting from the thrusting of Dalradian rocks over a possibly still active Ordovician arc. Cathodoluminescence microscopy distinguishes four phases of vein quartz in the Curraghinalt gold prospect. Fluid inclusion studies and stable isotope geochemistry have defined the probable fluids responsible for the precipitation of each quartz phase and associated sulfide and precious metal mineralization. The initial phase (Q1) appears to have been associated with the main Caledonian metamorphic event (ca. 470 Ma) and is nonauriferous. The second phase (Q2) forms an extensive cement to brecciated early quartz and is believed to have involved a fluid (∼115 wt % CO 2, 10 wt % NaCl + KCl equiv) with a significant magmatic component of 470 to 400 Ma, which underwent phase separation and dilution with a cooler water. This process resulted in precipitation of the main phase of gold mineralization characterized by an assemblage of electrum, pyrite, arsenopyrite, chalcopyrite, tennantite-tetrahedrite, and various tellurides. Similar fluids are observed on a regional scale, concentrated within the hanging wall of the Omagh thrust, indicating an extensive fluid-flow event. The relative abundance of gold at the Curraghinalt and Cavanacaw prospects is thought to be due to higher fluid fluxes in favorable zones of dilation and closer proximity to the fluid source. The deposit was subsequently reactivated with the precipitation of later quartz (Q3-Q4) from a formation water believed to be resident in the Dalradian metasediments, which mixed with a low-temperature, high-salinity basinal brin
Wilkinson JJ, Earls G, 2000, A high-temperature hydrothermal origin for black dolomite matrix breccias in the Irish Zn-Pb orefield, MINERALOGICAL MAGAZINE, Vol: 64, Pages: 1017-1036, ISSN: 0026-461X
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- Citations: 27
Parnell J, Earls G, Wilkinson JJ, et al., 2000, Regional fluid flow and gold mineralization in the Dalradian of the Sperrin Mountains, northern Ireland, ECONOMIC GEOLOGY AND THE BULLETIN OF THE SOCIETY OF ECONOMIC GEOLOGISTS, Vol: 95, Pages: 1389-1416, ISSN: 0361-0128
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- Citations: 39
Cole A, Wilkinson JJ, Halls C, et al., 2000, Geological characteristics, tectonic setting and preliminary interpretations of the Jilau gold-quartz vein deposit, Tajikistan, MINERALIUM DEPOSITA, Vol: 35, Pages: 600-618, ISSN: 0026-4598
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- Citations: 50
Gleeson SA, Wilkinson JJ, Shaw HF, et al., 2000, Post-magmatic hydrothermal circulation and the origin of base metal mineralization, Cornwall, UK, JOURNAL OF THE GEOLOGICAL SOCIETY, Vol: 157, Pages: 589-600, ISSN: 0016-7649
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- Citations: 30
Wilkinson JJ, Boyce AJ, Earls G, et al., 1999, Gold remobilization by low-temperature brines: Evidence from the Curraghinalt gold deposit, Northern Ireland, ECONOMIC GEOLOGY AND THE BULLETIN OF THE SOCIETY OF ECONOMIC GEOLOGISTS, Vol: 94, Pages: 289-296, ISSN: 0361-0128
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- Citations: 54
Everett C, Wilkinson JJ, Rye DM, 1999, Fracture-controlled fluid flow in the Lower Palaeozoic basement rocks of Ireland: Implications for the formation of Irish-type Zn-Pb deposits, Fractures, fluid flow and mineralization, Editors: McCaffrey, Lonergan, Wilkinson, Pages: 247-276
Cole A, Wilkinson JJ, Halls C, 1999, Geology and mineralisation of the Jilau gold deposit, Tajikistan, Rotterdam, 5th biennial meeting of the society-for-geology-applied-to-mineral-deposits / 10th quadrennial symposium of the international-association-on-the-genesis-of-ore-deposits, AUG 22-25, 1999, LONDON, ENGLAND, Publisher: A A Balkema, Pages: 333-336
Lonergan L, Wilkinson JJ, McCaffrey KJW, 1999, Fractures, Fluid Flow and Mineralisation: An Introduction, Fractures, Fluid Flow and Mineralisation, Editors: McCaffrey, Lonergan, Wilkinson, McCaffrey, Lonergan, Wilkinson, Pages: 1-6
Gleeson SA, Wilkinson JJ, Boyce AJ, et al., 1999, On the occurrence and wider implications of anomalously low deltaD fluids in quartz veins, South Cornwall, England, Chemical Geology (Isotope Geoscience), Vol: 160, Pages: 161-173
McCaffrey KJW, Lonergan L, Wilkinson JJ, 1999, Fractures, Fluid Flow and Mineralisation, Publisher: Geological Society of London Special Publication no. 155, ISBN: 1-86239-034-7
Rowland MG, Wilkinson JJ, 1999, Significance of intermediate stage veins at Quebrada Blanca, Chile, Rotterdam, 5th Biennial SGA and 10th Quadrennial IAGOD Meeting, London, Publisher: A.A. Balkema, Pages: 99-102
Boyce AJ, Fallick AE, Little CTS, et al., 1999, A hydrothermal vent tube worm in the Ballynoe baryte deposit, Silvermines, Ireland: implications for timing and ore genesis, Rotterdam, 5th Biennial SGA and 10th Quadrennial IAGOD Meeting, London, Publisher: A.A. Balkema, Pages: 825-827
Gleeson SA, Banks DA, Everett C, et al., 1999, Origin of mineralising fluids in Irish type deposits: constraints from halogens, Rotterdam, 5th Biennial SGA and 10th Quadrennial IAGOD Meeting, London, Publisher: A.A. Balkema, Pages: 857-860
Everett C, Wilkinson JJ, Boyce AJ, et al., 1999, The genesis of Irish-type Zn-Pb deposits: Characterisation and origin of the principal ore fluid, Rotterdam, 5th Biennial SGA and 10th Quadrennial IAGOD Meeting, London, Publisher: A.A. Balkema, Pages: 845-848
Hopkinson L, Roberts S, Herrington RJ, et al., 1999, The nature of crystalline silica from the TAG submarine hydrothermal mound, 26N Mid Atlantic Ridge, Contributions to Mineralogy and Petrology, Vol: 137, Pages: 342-350
Hopkinson L, Roberts S, Herrington RJ, et al., 1998, Self-organisation of submarine hydrothermal siliceous deposits: Evidence from the TAG hydrothermal mound, 26N Mid-Atlantic Ridge, Geology, Vol: 26, Pages: 347-350
Wilkinson JJ, Lonergan L, Fairs T, et al., 1998, Fluid inclusion constraints on conditions and timing of hydrocarbon migration and quartz cementation in Brent Group reservoir sandstones, northern North Sea, Dating and duration of fluid flow and fluid-rock interaction, Editors: Parnell, Publisher: Geological Society of London, Pages: 69-89, ISBN: 9781862390195
Rowland MR, Wilkinson JJ, 1998, A hybrid origin for porphyritic magmas sourcing mineralising fluids, Rotterdam, 9th Int. Conference on Water-rock interaction, Publisher: A.A. Balkema, Pages: 569-573
Williamson BJ, Stanley CJ, Wilkinson JJ, 1997, Implications from inclusions in topaz for greisenisation and mineralisation in the Hensbarrow topaz granite, Cornwall, England, CONTRIBUTIONS TO MINERALOGY AND PETROLOGY, Vol: 127, Pages: 119-128, ISSN: 0010-7999
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- Citations: 31
Boyce AJ, Wilkinson J, Earls G, et al., 1997, The identification and role of three fluids in the genesis of a mesozonal gold deposit at Curraghinalt, Northern Ireland, Rotterdam, Mineral Deposits: Research and Exploration - Where do they meet?, Publisher: A.A. Balkema, Pages: 161-163
Wilkinson JJ, Lonergan L, Fairs T, et al., 1997, Fluid inclusion constraints on brine-hydrocarbon migration into Brent Group reservoir sandstones, northern North Sea, Chippenham, Geofluids II, Publisher: Antony Rowe Ltd., Pages: 170-173
Wilkinson JJ, Johnston JD, 1996, Pressure fluctuations, phase separation, and gold precipitation during seismic fracture propagation, Geology, Vol: 24, Pages: 395-398, ISSN: 0091-7613
Gold mineralization at Croagh Patrick, western Ireland, occurs in quartz veins associated with three synchronous oblique tensile shear systems. The veins evolved by progressive thickening of isolated, en echelon, lensoid tensile fractures that show a power-law relation between their length and thickness. A change in power-law exponent marks the linking of the en echelon arrays by large, oblique-tensile veins. Fluid-inclusion data show that gold was deposited due to unmixing of an H2O-CO2-NaCl fluid at 320-240°C and 160-30 MPa primarily due to decreases in fluid pressure. Evidence for phase separation is only observed in the large linking veins and is abundant close to intersections of the vein arrays. These sites are where high gold grades occur. The distribution of gold is believed to reflect both spatial and temporal variations in fluid pressure fluctuation during seismic fracture propagation, controlled by the vein growth mechanism and zones of maximum dilation.
Wilkinson JJ, Nolan J, Rankin AH, 1996, Silicothermal fluid: A novel medium for mass transport in the lithosphere, Geology, Vol: 24, Pages: 1059-1062, ISSN: 0091-7613
New experimental data from synthetic fluid-inclusion studies in the system K2O-CO2-SiO2-H2O (KCSH) show that a potassic, silica-rich (≈90 wt% SiO2) fluid can coexist immiscibly with a supercritical, alkaline, aqueo-carbonic fluid and quartz from temperatures as low as 300°C to more than 750°C at relatively low geologic pressures (<200 MPa). This type of fluid phase may form in a range of geologic environments, including carbonatite complexes, alkaline subvolcanic-plutonic systems, and subduction zones. With a probable polymerized (silica-rich, melt-like) structure, such SiO2-rich fluids, if they form in the lithosphere, are likely to be important in the mobilization and transport of silica and large ion lithophile elements (e.g., K, Cs, Ba) and metals of economic significance (e.g., Au, Ag, U).
Wilkinson JJ, Rankin AH, Nolan J, 1996, Silicothermal fluid: A novel medium for mass transport in the lithosphere, Geology, Vol: 24, Pages: 1059-1062
Earls G, Hutton DHW, Wilkinson JJ, et al., 1996, The gold metallogeny of northwest Northern Ireland, Belfast, Northern Ireland, Publisher: Geological Survey of Northern Ireland
WILKINSON JJ, JENKIN GRT, FALLICK AE, et al., 1995, OXYGEN AND HYDROGEN ISOTOPIC EVOLUTION OF VARISCAN CRUSTAL FLUIDS, SOUTH CORNWALL, UK, CHEMICAL GEOLOGY, Vol: 123, Pages: 239-254, ISSN: 0009-2541
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- Citations: 47
COLES BJ, GLEESON SA, WILKINSON JJ, et al., 1995, IMPROVED DETECTION LIMITS FOR TRANSIENT SIGNAL ANALYSIS OF FLUID INCLUSIONS BY INDUCTIVELY-COUPLED PLASMA-ATOMIC EMISSION-SPECTROMETRY USING CORRELATED BACKGROUND CORRECTION, International Symposium on the Analysis of Geological and Environmental Materials (Geoanalysis 94), Publisher: ROYAL SOC CHEMISTRY, Pages: 1421-1425, ISSN: 0003-2654
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- Citations: 6
WILKINSON JJ, 1994, A NEW SYSTEM FOR HIGH-MAGNIFICATION THERMOMETRIC STUDIES OF FLUID INCLUSIONS IN DAIGENETIC MINERALS, JOURNAL OF SEDIMENTARY RESEARCH SECTION A-SEDIMENTARY PETROLOGY AND PROCESSES, Vol: 64, Pages: 701-703, ISSN: 1073-130X
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- Citations: 1
WILKINSON JJ, RANKIN AH, MULSHAW SC, et al., 1994, LASER ABLATION-ICP-AES FOR THE DETERMINATION OF METALS IN FLUID INCLUSIONS - AN APPLICATION TO THE STUDY OF MAGMATIC ORE FLUIDS, 4th Biennial Pan-American Conference on Research on Fluid Inclusions (Pacrofi IV), Publisher: PERGAMON-ELSEVIER SCIENCE LTD, Pages: 1133-1146, ISSN: 0016-7037
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- Citations: 24
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