5 results on '"McInnes, Paul"'
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2. The community garden hack.
- Author
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Karimi, Arafeh, Worthy, Peter, McInnes, Paul, Bodén, Marie, Matthews, Ben, and Viller, Stephen
- Published
- 2017
- Full Text
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3. Swept away, the two towns where 20,000 are missing
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Sawer, Patrick, Mendick, Robert, Foster, Peter, Gilligan, Andrew, McInnes, Paul, Alexander, Harriet, Goddard, Jacqui, Howie, Michael, Koike, Kazuko, Leach, Ben, Lusher, Adam, Luttman, Hisano, Nikkhah, Roya, Rayment, Sean, Solloway, Akemi, Suzuki, Eriko, and Yamada, Chieko
- Subjects
General interest ,News, opinion and commentary ,Twitter (Online social network) - Abstract
Byline: PATRICK SAWER and ROBERT MENDICK, Peter Foster, Andrew Gilligan and Paul McInnes in Tokyo, Harriet Alexander, Jacqui Goddard, Michael Howie, Kazuko Koike, Ben Leach, Adam Lusher, Hisano Luttman, Roya [...]
- Published
- 2011
4. Genesis and Exploration Implications of Epithermal Gold Mineralization and Porphyry-Style Alteration at the Endeavour 41 Prospect, Cowal District, New South Wales, Australia.
- Author
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ZUKOWSKI, WOJCIECH, COOKE, DAVID R., DEYELL, CARI L., MCINNES, PAUL, and SIMPSON, KIRSTIE
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MINERALIZATION ,PYRITES ,ISOTOPES ,ROCK-forming minerals ,MAGNETITE - Abstract
Endeavour 41 is a deep-level, structurally controlled epithermal gold deposit hosted by Early Ordovician subaqueous volcanosedimentary rocks. Calc-alkalic to shoshonitic, mafic to intermediate sills, dikes, and stocks intruded the volcanosedimentary units in the Middle Ordovician. The most felsic intrusions, together with pyroxene-bearing dikes, are temporally related to gold mineralization. Postmineralization intrusions are exclusively of mafic character. Endeavour 41 evolved from early, high-temperature porphyry-style veins and alteration to lower-temperature epithermal-style gold mineralization. Early magnetite and garnet-bearing veins (stage 1 and 2, respectively) associated with actinolite, magnetite, and biotite-bearing alteration assemblages have been cut by gold-bearing veins and associated alteration assemblages. There were two main epithermal-style gold mineralizing events: (1) quartz-pyrite ± calcite ± adularia ± chlorite veins (stage 3) and (2) carbonate-base metal sulfide veins (calcite, ankerite, quartz, pyrite, sphalerite, galena, chalcopyrite, Ag tellurides, arsenopyrite, apatite, hematite, illite-muscovite, and chlorite [stage 4]). Gold occurs principally as a refractory phase in pyrite. It also occurs as grains of Au-Ag tellurides and as inclusions of free gold in pyrite, sphalerite, and chalcopyrite. Hydrothermal alteration associated with gold-mineralized veins produced early epidote and K-feldspar-epidote-bearing alteration halos and later-stage illite-muscovite-K-feldspar and calcite-rich alteration halos. The highest gold grades are associated with muscovite and illite alteration. Stable isotope analyses and fluid inclusion data provide evidence of a magmatic-hydrothermal component to the mineralizing fluids. Fluid inclusion data suggest that gold precipitated from boiling saline waters (~9.0 wt % NaC1) at temperatures of about 310°C. Stage 3 veins are estimated to have formed approximately 1 km below the paleosurface at hydrostatic pressure (~90 bars). Stage 4 illite formed at temperatures below ~280°C. Stage 3 calcite has δ
13 Ccalcite and δ18 Ccalcite values that range from ~5.2 to -4.6 and from 11.6 to 12.1%o, respectively. Calculated fluids for these mineral values at 300°C (δ13 Cfluid = -3%; δ18 Cfluid = 6%) are consistent with a magmatic-hydrothermal source of carbon and oxygen during stage 3. A component of meteoric waters is inferred for stage 4, because δ13 Ccarbonate and δ18 Ccarbonate values range from -6.9 to -0.5 and from 10.9 to 30.1%o, respectively, corresponding to δ13 Cfluid and δ18 Cfluid values of-5 and -2%c at 200° to 250°C. The δ34 Csulfide values for early vein stages range between -4.9 and -0.5%o. Stage 3 has δ34 Csulfide values ranging from -5.2 to +0.8% with the most34 S enriched values deposited away from the mineralized center. Stage 4 sulfides have isotopic compositions from -7.5 to +2.5%c. The negative isotopic values are consistent with oxidized (sulfate-predominant) magmatic-hydrothermal fluids. Sulfur isotopic zonation patterns show that the most negative34 S values correlate with gold-enriched domains and also with areas that contain high-temper ature, porphyry-style alteration fades. The negative sulfur isotope values define zones of upflow for the mineralizing magmatic-hydrothermal fluids. The paragenetic history of Endeavour 41 records a transition from deep-level to shallow-level magmatic-hydrothermal activity. This transition implies erosion and unroofing of the system synchronous with mineralization. High-temperature assemblages (e.g., actinolite-magnetite, biotite, and K-feldspar-epidote) indicate that epithermal mineralization occurred proximal to a magmatic-hydrothermal center and that there is potential for the discovery of porphyry copper-gold mineralization below the current level of diamond drilling. [ABSTRACT FROM AUTHOR]- Published
- 2014
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5. Structural Evolution of Auriferous Veins at the Endeavour 42 Gold Deposit, Cowal Mining District, NSW, Australia.
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HENRY, AMBER D., MCINNES, PAUL, and TOSDAL, RICHARD M.
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STRUCTURAL geology ,MINERAL industries ,IGNEOUS intrusions ,ORDOVICIAN Period ,PALEOZOIC Era - Abstract
Polyphase veins at the low-grade, structurally controlled epithermal gold deposit Endeavour 42 in the Junee-Narromine volcanic belt of the Ordovician to Silurian Macquarie Arc, central New South Wales (Australia), record multiple tectonically driven fluid-flow events during the mid-Paleozoic. Ordovician host rocks consist of a volcano-sedimentary succession intruded by traehyandesite and andesitic lavas and intrusions, as well as a volumetric-ally significant Ordovician diorite sill. The entire succession was tilted and faulted prior to the emplacement of multiple mafic to intermediate dike phases, commonly localized along faults. Gold-bearing veins cut all lithologic units at the Endeavour 42 deposit, with the exception of rare late-stage intrusions. Economic gold is restricted to faults, fault-hosted breccias, and veins with two distinct populations: (1) an older, steeply dipping conjugate vein set, cut by (2) two younger, moderately dipping vein sets. Both steep and inclined, moderately dipping vein sets contain a similar mineral assemblage, implying formation during a single epithermal system. Veins are generally 1 to 10 mm thick, commonly straight walled, but locally form overlapping veins with hard linkages. The steep veins reactivated two sets of older faults, fault-parallel fractures, and dike contacts, and accommodated subhorizontal extension. High gold grade, hydrothermally cemented breccias are associated with early gold-bearing veins and localized along deposit-scale faults. Crosscutting the early steep gold-bearing vein sets are inclined gold-bearing veins with moderate dips to the southwest and west. These opened as a new vein set and as veins localized along and at a slight angle to westward-dipping bedding planes, respectively. The geometry of the inclined, moderately dipping veins either represents a sudden change in the far-field stress state to near-vertical minimum compressive stress, thereby suggesting a change from an extensional to a contractional environment, or it may reflect local changes in the differential stress state with subhorizontal northeast-southwest tension. Late veins and thrust faults in the deposit indicate a postmineral contractional environment. The Endeavour 42 deposit underwent tectonic burial until it was exhumed in the early Carboniferous, as indicated by
40 Ar/39 Ar plateau ages of 362.7 ± 2.1, 356.3 ± 1.8, and 344.5 ± 2.1 Ma, toward the end of the Kanimblan Cycle. [ABSTRACT FROM AUTHOR]- Published
- 2014
- Full Text
- View/download PDF
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