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Province-scale commonalities of some world-class gold deposits:Implications for mineral exploration

Geoscience Frontiers 2015年第3期6卷 389-399页

作者： David I.Groves m.Santosh Centre for Exploration Targeting UWA State Key Laboratory of Geological Processes and mineral Resources China University of Geosciences Centre for Tectonics Resources and Exploration Dept.of Earth SciencesUniversity of Adelaide Division of Interdisciplinary Science Faculty of ScienceKochi University

Discovery rates for all metals, including gold, are declining, the cost per significant discovery is increasing sharply, and the economic situation of the industry is one of low base rate. The current hierarchical structure of the exploration and mining industry makes this situation difficult to redress. Economic geologists can do little to influence the required changes to the overall structure and philosophy of an industry driven by business rather than geological principles, However, it should be possible to follow the lead of the oil industry and improve the success rate of greenfield exploration, necessary for the next group of lower-exploration-spend significant mineral deposit discoveries. Here we promote the concept that mineral explorers need to carefully consider the scale at which their exploration targets are viewed. It is necessary to carefully assess the potential of drill targets in terms of terrane to province to district scale, rather than deposit scale, where most current economic geology research and conceptual thinking is concentrated. If orogenic, IRGD, Carlin-style and IOCG gold-rich systems are viewed at the deposit scale, they appear quite different in terms of conventionally adop- ted research parameters. However, recent models for these deposit styles show increasingly similar source-region parameters when viewed at the lithosphere scale, suggesting common tectonic settings. It is only by assessing individual targets in their tectonic context that they can be more reliably ranked in terms of potential to provide a significant drill discovery. Targets adjacent to craton margins, other lithosphere boundaries, and suture zones are clearly favoured for all of these gold deposit styles, and such exploration could lead to incidental discovery of major deposits of other metals sited along the same tectonic boundaries.

关键词： mineral exploration Gold deposits Tectonic settings mining industry Discovery rate

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Petrogenesis of Granites from the Utla Area of Gadoon, North-West Pakistan: Implications from Petrography and Geochemistry

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Journal of Earth Science 2014年第3期25卷 445-459页

作者： muhammad Sajid mohammad Arif m Tahir Shah Department of Geology University of Peshawar National Center of Excellence in Geology University of Peshawar

The granitic rocks around the Utla area（Gadoon）, north western, Pakistan are studied in terms of their petrographic features and geochemical characteristics. Although predominantly mega-porphyritic, some of the Utla granites are massive and display fine-grained equi-granular texture. Some of the mega-porphyritic varieties exhibit foliation and seem to be restricted to shear zones. In addition to being distributed largely as phenocrysts, all the essential minerals（plagioclase, perthitic alkali feldspar and quartz） also constitute the groundmass. The studied samples also contain minor to accessory amounts of tourmaline, muscovite and biotite and accessory to trace amounts of apatite, andalusite, garnet, zircon, monazite, epidote and sphene. A detailed geochemical investigation reveals a calc-alkaline and peraluminous character of the Utla granites. The peraluminous character and total lack of hornblende designate their S-type character while a volcanic arc or syn-collisional tectonic setting for their emplacement is indicated by discrimination diagrams. Further examination shows that the melt parental to the Utla granite was derived from a plagioclase-poor, clay-rich rock, i.e., pelite. The petrogenetically significant petrographic and geochemical features of the Utla granite show greater similarity with the mansehra than the Ambela granites. These include（i） the predominantly megaporphyritic texture,（ii） the presence of andalusite and tourmaline,（iii） the calc-alkaline geochemical signature and（iv） an indication of similar melt source rock character.

关键词： petrography geochemistry granite Utla Pakistan.

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mining diversity of the natural biorefinery housed within Tipula abdominalis larvae for use in an industrial biorefinery for production of lignocellulosic ethanol

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Insect Science 2010年第3期17卷 303-312页

作者： Dana m. Cook Joy Doran-Peterson microbiology Department University of Georgia Athens Georgia USA

Although they are the largest taxonomic group of animals, relatively few insects have been examined for symbiotic relationships with micro-organisms. However, this is rapidly changing because of the potential for examination of the natural insectmicrobe-lignocellulose interactions to provide insights for biofuel technology. micro-organisms associated with lignocellulose-consuming insects often facilitate the digestion of the recalcitrant plant diet; therefore these microbial communities may be mined for novel lignocellulose-degrading microbes, or for robust and inexpensive biocatalysts necessary for economically feasible biofuel production from lignocellulose. These insect-microbe interactions are influenced by the ecosystem and specific lignocellulose diet, and appre- ciating the whole ecosystem-insect-microbiota-lignocellulose as a natural biorefinery provides a rich and diverse framework from which to design novel industrial processes. One such natural biorefinery, the Tipula abdominalis larvae in riparian ecosystems, is reviewed herein with applications for biochemical processes and overcoming challenges involved in conversion of lignocellulosic biomass to fuel ethanol. From the dense and diverse T. abdominalis larval hindgut microbial community, a cellulolytic bacterial isolate, 27C64, demonstrated enzymatic activity toward many model plant polymers and also produced a bacterial antibiotic. 27C64 was co-cultured with yeast in fermentation of pine to ethanol, which allowed for a 20% reduction of commercial enzyme. In this study, a micro-organism from a lignocellulose-consuming insect was successfully applied for improvement of biomass-to-biofuel technology.

关键词： ethanol hydrolytic enzymes insect-associated microorganisms lignocellulose

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mechanistic Investigation into the Role of Aluminum Diffusion in the Oxidation Behavior of Cryomilled NiCrAlY Bond Coat

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Journal of Wuhan University of Technology(materials Science) 2016年第1期31卷 35-43页

作者： Kaka mA Xiaochuan TANG Julie m SCHOENUNG Department of Chemical Engineering and materials Science University of California Davis Genome and Biomedical Science Facility Genome CenterUniversity of California Davis

High temperature oxidation behavior of the bond coat layer is a critical factor that controls the failure mechanism of thermal barrier coatings（TBCs）.Previous work reveald that TBCs with cryomilled NiCrAlY bond coats exhibited an improved oxidation behavior compared to equivalent TBCs with conventional bond *** cryomilled NiCrAlY bond coats contributed to a slower growth rate of thermally grown oxides（TGO） with a final thinner thickness and enhanced homogeneity in TGO *** better understand the improved oxidation behavior,a mechanistic investigation based on diffusion theory and quantum mechanics is performed to elucidate the role of aluminum diffusion in the oxidation behavior and how the microstructural features of the cryomilled NiCrAlY bond coats,i e,the creation of a thermally stable,uniform distribution of ultrafine Al-rich oxide dispersoids,affect the diffusion kinetics of Al and the migration of free *** is revealed that these Al-rich oxide dispersoids result in a uniform diffusion of Al and slow migration of free electrons within the NiCrAlY bond coat,consequently leading to the improved oxidation behavior.

关键词： nickel alloys coatings oxidation diffusion

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Risk reduction in Sechahun iron ore deposit by geological boundary modification using multiple indicator Kriging

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Journal of Central South University 2014年第5期21卷 2011-2017页

作者： S.Kasmaee F.m.Torab Department of mining and metallurgical Engineering Iranian Iron Ore Research Center(IORC)Yazd University Department of mining and metallurgical Engineering Yazd University

Uncertainty on the geological contacts and the block volumes of the models along boundaries is often a major part of the global uncertainty of reserve *** work introduces a geostatistical technique that has been developed and tested in an iron ore deposit at Bafq mining district,in central Iran,and that,based on a probability criterion,helps to objectively model the geometry of this iron ore *** main problem in reserve estimation of this ore body is its geometrical modeling and uncertainty in geological *** work deals with the geostatistical method of multiple indicator kriging,which is used to determine the real boundaries of ore body in different *** approach has potential to improve project performance and decrease operational *** this purpose,the ore body is separated into two categories including rich iron zone(w(Fe)>45%)and poor iron zone(20%multiple indicator kriging as a tool for estimates the position of grade boundaries within the *** of the resultant probability maps with the real ore/waste contacts on the extracted levels shows that the first indicator model could separate the whole ore body(poor plus rich)from the waste zone by probability of more than 0.35,which concludes the total reserve of 53 million *** second indicator model applied to separate the rich and poor domains and the results show that the blocks with the estimated probability of equal to or more than 0.4 lay within the rich ore zone consisting of 15.8 million tons reserve.

关键词： geological boundaries multiple indicator kriging risk assessment block model uncertainty Sechahun deposit

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Point of Zero Salt Effect: Relationships with Clay mineralogy of Representative Soils of the So Paulo State, Brazil

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Pedosphere 2005年第5期15卷 545-553页

作者： m. E. ALVES A. LAVORENTI Departamento de Física e Informática Institute de Física de So Carlos-IFSC/USP So Carlos (SP) 13560-970(Brazil). Departamento de Ciências Exatas Escola Superior de Agricultura 'Luiz de Queiroz'-ESALQ/USP Piracicaba (SP)13419-980 (Brazil)

The point of zero salt effect （PZSE） is the soil pH value at which the magnitude of the variable surface charges is not changed due to variations in the ionic concentration of the soil solution. This property influences not only electrochemical phenomena occurring at the solid-solution interface but also the flocculation degree of the soil particles. In this study we investigated the relationships between the clay mineralogy and the PZSE values of representative soils of the Sāo Paulo State, Brazil. The results confirmed the usefulness of the difference between the soil pH values measured in 1 mol L^-1 KCl （pHKCl） and in water （pHH2O）（2 pHKCl-pHH2O） for estimating the PZSE of tropical soils, except for the ones rich in exchangeable Al; furthermore, the ApH index （pHKC1 - pHH2O） was highly correlated with the difference between the PZSE and pHH2O values, reiterating the △pH utility for estimating both the signal and the magnitude of the net surface charge of tropical soils. Finally, correlation and multiple regression analyses showed that the PZSE value of weathered non-allophanic tropical soils tends to increase and to equal the soil pH due to the weathering-induced kaolinite destabilization and concomitant Fe- and Al-oxide accumulation.

关键词： electrochemical properties iron oxides kaolinite tropical soils weathered soils

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The giant Jiaodong gold province： The key to a unified model for orogenic gold deposits？

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Geoscience Frontiers 2016年第3期7卷 409-417页

作者： David I.Groves m.Santosh Centre for Exploration Targeting UWA Cmwley 6009 WA Australia Centre for Tectonics Resources and Exploration Department of Earth Sciences University of Adelaicle SA 5005 Australia State Key Laboratory of Geological Processes and mineral Resources China University of Geosciences Beijing 100083 China Division of Interdisciplinary Science Faculty of Science Kochi University Kochi 780-8520 Japan

Although the term orogenic gold deposit has been widely accepted for all gold-only lode-gold deposits,with the exception of Carlin-type deposits and rare intrusion-related gold systems,there has been continuing debate on their *** syngenetic models and hydrothermal models dominated by meteoric fluids are now clearly ***-hydrothermal models fail to explain the genesis of orogenic gold deposits because of the lack of consistent spatially- associated granitic intrusions and inconsistent temporal *** most plausible,and widely accepted,models involve metamorphic fluids,but the source of these fluids is hotly *** within deeper segments of the supracrustal successions hosting the deposits,the underlying continental crust,and subducted oceanic lithosphere and its overlying sediment wedge all have their *** orogenic gold deposits of the giant Jiaodong gold province of China,in the delaminated North China Craton,contain ca.120 ma gold deposits in Precambrian crust that was metamorphosed over 2000 million years prior to gold *** only realistic source of fluid and gold is a subducted oceanic slab with its overlying sulfide-rich sedimentary package,or the associated mantle *** could be viewed as an exception to a general metamorphic model where orogenic gold has been derived during greenschist- to amphibolite-facies metamorphism of supracrustal rocks：basaltic rocks in the Precambrian and sedimentary rocks in the ***,if a holistic view is taken,Jiaodong can be considered the key orogenic gold province for a unified model in which gold is derived from late-orogenic metamorphic devolatilization of stalled subduction slabs and oceanic sediments throughout Earth *** latter model satisfies all geological,geochronological,isotopic and geochemical constraints but the precise mechanisms of auriferous fluid release,like many other subduction-related processes,are model-driv

关键词： Jiaodong province Orogenic gold metamorphic fluids Subduction zones Tectonics

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Effect of stirring on preparation of hollow copolymer particles by alkali/cooling method

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Journal of Central South University 2009年第4期16卷 563-568页

作者：李海普 OKUBO m SUZUKI T School of Chemistry and Chemical Engineering Central South University Graduate School of Science and Technology Kobe University

Hollow particles were prepared by the treatment of styrene-metbacrylic acid copolymer particles with alkali/cooling method. The influences of stirring position （in aqueous phase or at the interface of O/W） and stirring speed （90, 110 and 240 r/min） on the formation of hollow particles were investigated. It is found that the soft stirring in aqueous phase at 90 r/min leads to the formation of monohollow particles, while the violent stirring at the interface of O/W and 240 r/min gives non-hollow products. In contrast, the weak stirring in aqueous phase at 110 r/min results in sterically heterogeneous dispersion of methacrylic acid-rich regions within the original particles, and hence the formation of multihollow particles. Further investigation indicates that the change of stirring efficiency provides a way to tune the diffusion behavior of monomer styrene, and therefore influences the distribution of methacrylic acid units in the original particles as well as the morphology of the treated particles.

关键词： hollow polymer particle stirring effect morphology emulsion copolymerization

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Acoustic-electrical properties and rock physics models for shale-oil formations:prediction of reservoir properties of interbedded sandstone and shale layers

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Applied Geophysics 2022年第4期19卷 485-502,603页

作者： Pang meng-Qiang Ba Jing Wu Chun-Fang Carcione José maria müller Tobias School of Earth Science and Engineering Hohai UniversityNanjingu211000China Bochum University of Applied Sciences D-44801 BochumGermany Shanghai Technical Institute of Electronics and Information Shanghai201411China National Institute of Oceanography and Applied Geophysics(OGS) SgonicoTrieste 34010

In recent years,the Yanchang shale-oil formations of the Ordos Basin are rich in reserves with complex lithology and structure characteristics,low porosity and low permeability,and weak anomalies for oil and water discriminations,have been the key targets of unconventional oil/gas resource exploration and development in the relevant *** joint acoustic-electrical(AE)properties can be used to interpret reservoir lithology,mineralogy,pore structure,and fluid *** conduct tests of thin section analysis,X-ray diff raction,and ultrasonic and electrical experiments at diff erent pressures and saturation degrees,cores from the shale-oil formations in the Q area of the basin are *** variations in AE properties with respect to clay content,porosity,pressure(microfracture),and saturation are *** experimental results indicate that the rock physics behaviors of sandstones with diff erent clay contents vary *** AE properties of clean sandstones are basically dependent on the microfractures(pressure),while for muddy sandstones,the clay content is an important factor affecting the *** target reservoir consists of interbedded sandstone and shale *** AE equivalent medium equations and the Gurevich theory are applied to establish the joint models for the diff erent lithologies and simulate the variations in AE properties with respect to fluid type,pore structure,and mineral *** three-dimensional joint templates of clean and muddy sandstones,as well as shale,are developed based on the elastic and electrical attributes and then calibrated using the experimental and well-log *** reservoir properties are estimated with the templates and validated by the log *** results indicate that the joint templates based on lithology characteristics can eff ectively characterize the properties of interbedded sandstone and shale ***,the combined application of AE data provides more beneficial informatio

关键词： shale-oil formations acoustic-electrical(AE)properties interbedded layers clay content pore structure rock physics model

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magnetic Properties of Nd-Fe-B Sintered magnet Powders Recovered by Yb metal Vapor Sorption

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Journal of Rare Earths 2004年第1期22卷 152-156页

作者： Horikawa T Itoh m Suzuki Shunji machida K Collaborative Research Center for Advanced Science and Technology Collaborative Research Center for Advanced Science and TechnologyCollaborative Research Center for Advanced Science and TechnologyCollaborative Research Center for Advanced Science and Technology Osaka University Osaka 565-0871 Japan Osaka University Osaka 565-0871 Japan Osaka University Osaka 565-0871 Japan Osaka University Osaka 565-0871 Japan

Fine ground powders of Nd-Fe-B sintered magnet bulks (particle size=46～125 μm in diameter) were coated and alloyed with Yb metal by sorbing them. A significant recovery of the decreased magnetic properties of the ground powders (remanence B r=～0.95 T, coercivity H cj =～227 kA·m -1 and maximum energy product (BH) max=～48 8 kJ·m -3) was observed in accordance with increasing temperature up to 800 ℃. The sorbing temperature and time for Yb metal vapor were optimized and after heating at 800 ℃ for 90 min and annealing subsequently at 610 ℃ for 60 min, the B r, H cj and (BH) max values were increased to be 0.98 T, 712 kA·m -1 and 173 kJ·m -3, respectively. From the microstructural characterizations of resulting samples by using X-ray diffraction (Xrd), scanning electron microscopy (SEm), and electron probe X-ray microanalyzer (EPmA), it is found that the sorbed Yb metal uniformly covers the surface and diffuses to the Nd-rich grain boundary of fine ground powders of Nd-Fe-B sintered magnet bulks forming a (Nd,Yb)Fe 2 phase.

关键词： metal materials Nd 2Fe 14B sintered magnets metal vapor sorption magnetic properties recovery rare earths

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