Effect of pyrolysis conditions on bone char characterization and its ability for arsenic and fluoride removal
- Authors: Alkurdi, Susan , Al-Juboori, Raed , Bundschuh, Jochen , Bowtell, Les , McKnight, Stafford
- Date: 2020
- Type: Text , Journal article
- Relation: Environmental Pollution Vol. 262, no. (2020), p.
- Full Text: false
- Reviewed:
- Description: This study examined arsenite [As(III)], arsenate [As(V)] and fluoride (F−) removal potential of bone char produced from sheep (Ovis aries) bone waste. Pyrolysis conditions tested were in the 500 °C–900 °C range, for a holding time of 1 or 2 h, with or without N2 gas purging. Previous bone char studies mainly focused on either low or high temperature range with limited information provided on As(III) removal. This study aims to address these gaps and provide insights into the effect of pyrolysis conditions on bone char sorption capacity. A range of advanced chemical analyses were employed to track the change in bone char properties. As pyrolysis temperature and holding time increased, the resulting pH, surface charge, surface roughness, crystallinity, pore size and CEC all increased, accompanied by a decrease in the acidic functional groups and surface area. Pyrolysis temperature was a key parameter, showing improvement in the removal of both As(III) and As(V) as pyrolysis temperature was increased, while As(V) removal was higher than As(III) removal overall. F− removal displayed an inverse relationship with increasing pyrolysis temperature. Bone char prepared at 500 °C released significantly more dissolved organic carbon (DOC) then those prepared at a higher temperature. The bone protein is believed to be a major factor. The predominant removal mechanisms for As were surface complexation, precipitation and interaction with nitrogenous functional groups. Whereas F− removal was mainly influenced by interaction with oxygen functional groups and electrostatic interaction. This study recommends that the bone char pyrolysis temperature used for As and F− removal are 900 °C and 650 °C, respectively. © 2020 Elsevier Ltd
- Description: This research was performed as a part of PhD research which was supported in part by the Iraqi Government and the Australian Research Training Program.
Metamorphic style of the Tabberabbera zone, Lachlan Fold Belt
- Authors: Morand, Vincent J , McKnight, Stafford
- Date: 2006
- Type: Text , Conference paper
- Relation: Australian Earth Sciences Symposium, Melbourne 2/07/2006
- Full Text: false
- Description: 2003004226
Illite crystallinity and the b-spacing values of white micas and their implications for gold mineralisation in the Lachlan Orogen
- Authors: Wilson, C. , McKnight, Stafford , Dugdale, A. , Rawling, T. , Farrar, A. , McKenzie, M. , Melling, W.
- Date: 2009
- Type: Text , Journal article
- Relation: Australian Journal of Earth Sciences Vol. 56, no. 8 (2009), p. 1143-1164
- Full Text: false
- Reviewed:
- Description: Gold mineralisation in the Lachlan Orogen of western Victoria, is generally hosted in turbidites with very low-grade metamorphic assemblages. Metamorphic data from these turbidites are relatively rare because of the fine-grained nature of the pelitic component and lack of suitable assemblages for thermobarometric estimates. In this study, 'illite crystallinity' (Kubler Index) and b-lattice spacing measurements were carried out on white micas in metapelites, collected from near the inferred western margin of the Selwyn Block, as well as three exploration targets, in an attempt to relate thermal and barometric conditions to mineralisation. Higher-grade (epizone) metamorphic conditions are recorded in sequences west of the Whitelaw Fault and lower-grade (anchizone) metamorphic conditions to the east of the fault. The change from epizonal to anchizonal grade is abrupt, resolved to a distance of a few hundred metres. The b-spacing values change adjacent to the Muckleford Fault. This is due to rocks to the east being exhumed as the edge of the Selwyn Block moved westward during the Middle Devonian Tabberabberan Orogeny at 380Ma. We propose that the juxtaposition of rocks with contrasting thermal and barometric histories represents expression of the upper crustal location of the western margin of the Selwyn Block at the time of peak deformation, at about 440Ma, and this crustal structure controlled the distribution of the major quartz-vein-type gold deposits. The Middle Devonian orogenic activity (380Ma) was accompanied by the formation of disseminated gold deposits such as Fosterville. This represents a mineralising event that overprints the earlier gold deposits in a corridor at least 50km wide and to the west of the Whitelaw Fault, that parallels the margin of the Selwyn Block. The correlation between gold assays and 'illite crystallinity' results, from X-ray diffraction and from short-wave infrared-reflectance field-spectroscopy data, were ambiguous. Kubler Indices are not found to be effective in targeting of mineralisation as the values obtained from the alteration and the host-rock assemblages were similar and reflected the ambient P-T conditions at the time of mineralisation.
Evolution of the boundary between the western and central Lachlan Orogen : Implications for tasmanide tectonics
- Authors: Spaggiari, Catherine , Gray, David , Foster, David , McKnight, Stafford
- Date: 2003
- Type: Text , Journal article
- Relation: Australian Journal of Earth Sciences Vol. 50, no. 5 (2003), p. 725-749
- Full Text:
- Reviewed:
- Description: Differences in oblique overprinting, along-strike complexity as well as structural, metamorphic and timing constraints suggest that the boundary between the western and central subprovinces of the Lachlan Orogen, currently designated by the Governor Fault, cannot be a single structure. Previously limited data on the nature and kinematics of the fault/shear systems defining the boundary have led to varying scenarios for the tectonic evolution of the Lachlan Orogen. These scenarios either involve large-scale strike-slip displacement along the boundary with subsequent overthrusting or convergence of oppositely vergent thrust-systems with limited strike-slip translation. Geometrical constraints, fabric chronology and kinematic indicators in both the Mt Wellington (Melbourne Zone) and Governor (Tabberabbera Zone) Fault Zones indicate that maximum displacements relate to thrusting and duplex formation, followed by minor strike-slip faulting perhaps in response to slightly oblique collision of the Melbourne and Tabberabbera structural zones. Collision of these zones took place between ca 400 and 390 Ma. At Howqua, structural relationships indicate that collision involved northeast-directed thrusting of the Melbourne Zone (Mt Wellington Fault Zone) over the Tabberabbera Zone (Governor Fault Zone), and was followed by regional, northwest-trending, open folding. These structures overprint the dominant fabrics and metamorphic assemblages that are interpreted to relate to disruption and underthrusting of Cambrian oceanic/arc crust during closure of a marginal basin. Major deformation in the Tabberabbera Zone took place from ca 445 Ma and was associated with mélange formation, underplating and imbrication or duplexing (Governor Fault Zone, East Howqua segmennt). At slightly higher crustal levels, and following deposition of Upper Ordovician black shale and chert sequences (ca 440 Ma), Tabberabbera Zone evolution included offscraping of a serpentinite body (Dolodrook segment) that may have been either a Marianas-style seamount or transform fault zone within the Cambrian oceanic/arc crust. Major thrusting in the Mt Wellington Fault Zone was underway sometime after ca 420 Ma, and in contrast to the Governor Fault Zone, no mélange or broken formation was produced, metamorphism was at slightly higher temperatures and deformation probably occurred under higher strain states.
- Description: C1
- Description: 2003000547
Characterization and recovery of gold associated with fine, activated carbon
- Authors: Rowe, James , McKnight, Stafford
- Date: 2009
- Type: Text , Conference paper
- Relation: Paper presented at World Gold Conference 2009, Johannesburg, South Africa : 26th-30th October 2009
- Full Text:
- Description: The attrition of activated carbon, and the loss of gold associated with it, is of significant economic importance to the operation of a CIP/CIL circuit. The focus of this study was on activated carbon recovered from an elution circuit which was deemed too fine for reuse. Results of cyclosizer and laser particle size analysis identified that most of the carbon was contained in the larger size fraction suggesting formation by abrasion. Digestion and AAS analysis of the individual size fractions identified a disproportionate concentration of gold in the finer size fractions which was identified by scanning electron microscopy to be due to the presence of fine metallic gold formed as a result of the acid washing process. Attempts to strip the remaining gold using sodium hydroxide or sodium sulphide based solutions proved unsuccessful due to poor elution efficiencies and re adsorption of gold. Upgrading of the material by froth flotation was also investigated using various conventional flotation reagents which had some success in concentrating the free metallic gold, however, grade and/or recoveries were considered less than desirable. Greater success was ultimately found in the transfer of gold from the fine carbon material onto coarser virgin activated carbon using a caustic cyanide solution. Sodium sulphide, sodium chloride and ammonium chloride based solutions were also trialled but proved less successful owing to their inability to mobilise metallic gold or gold cyanide species. Repetition of the transfer process proved capable of stripping 97% of the gold contained on the carbon fines for a bed volume ratio of 6:1.
- Description: 2003007482
Application of high voltage transmission electron microscopy to the study of ultra-fine grained ores
- Authors: McKnight, Stafford
- Date: 2004
- Type: Text , Conference paper
- Relation: Paper presented at The Minerals Industry - Future Directions for New Leaders', Ballarat, Victoria : 21st March, 2004
- Full Text: false
- Reviewed:
- Description: E1
- Description: 2003000706
The Fosterville (central Victoria, Australia) and globe-progress (Reefton, South Island, New Zealand) deposits : Examples of shear zone-related disseminated-style systems in low-grade metamorphic terrains
- Authors: Bierlein, Frank , Christie, Anthony B , McKnight, Stafford
- Date: 2002
- Type: Text , Conference paper
- Relation: 114th Annual Meeting of the Geological Society of America , Colorado
- Full Text: false
- Description: Orogenic gold deposits in central Victoria and Reefton formed during the evolution of a Paleozoic accretionary system along the Pacific margin of Gondwana. The majority of deposits in both camps are characterised by coarse-grained gold that is hosted in laminated to massive quartz veins. These ‘lode’ structures are developed in isoclinally folded turbidites that have been metamorphosed to lower greenschist facies. At Fosterville, diffuse zones of mineralization occur along a high-angle reverse fault zone consisting of en-échelon, strike-parallel segments with oblique slip and strike slip movement. The Globe-Progress deposit is associated with an arcuate shear that flattens with depth forming a listric ramp flat. In contrast to ‘classic’ lode-style deposits, mineralization at Fosterville and Globe-Progress is predominantly hosted by massive sandstone beds, in quartz/carbonate vein stockworks, and in clay-rich fault breccias of quartz vein and sulfidic wall rock fragments. The porous sandstones, which are intercalated with carbonaceous slates, have a bleached appearance, are invariably sericitized and carbonatized, and are 'impregnated' with a disseminated arsenopyrite-pyrite(±stibnite) assemblage. Gold occurs as sub-micron inclusions within the sulfides and rarely as free grains with a diameter of 1-10 microns. Highest-grade disseminated mineralization occurs within acicular arsenopyrite crystals. Fluid inclusions from Fosterville range in composition from high salinity and relatively high CO2, to low salinity and H2O-predominance, suggesting precipitation of at least a portion of the veins under epizonal conditions.....
- Description: 2003004220
Tectonic and economic implications of trace element, Ar-40/Ar-39 and Sm-Nd data from mafic dykes associated with orogenic gold minerals in central Victoria, Australia : reply
- Authors: Bierlein, Frank , Hughes, Martin , Dunphy, J. , McKnight, Stafford
- Date: 2002
- Type: Text , Journal article
- Relation: Lithos Vol. 63, no. 1-2 (Jul 2002), p. 119-123
- Full Text: false
- Reviewed:
The development of heavy suspension techniques for high density sink-float separations (replacement of Clerici's solution)
- Authors: Klutke, Cameron , Koroznikova, Larissa , McKnight, Stafford , Hall, Stephen
- Date: 2006
- Type: Text , Conference paper
- Relation: Paper presented at The AusIMM new Leaders Conference 2006, Kalgoorlie : 11th April, 2006
- Full Text: false
- Reviewed:
- Description: Mineral sands represent an important new resource being developed in the Murray Basin, including parts of western Victoria. This paper will outline a simple methodology for mineral sands characterisation, developed as part of the AMIRA-managed project P777 ‘The Development of Heavy Suspension Techniques for High Density Separations (Replacement of Clerici’s Solution)’. This project is currently sponsored by three multinational mining companies (De Beers Consolidated Mines, Iluka Resources Limited and Rio Tinto Limited) and is developing an innovative laboratory mineral characterisation procedure that will allow the replacement of the currently employed highly-toxic chemicals. Mineral sand resources almost always contain more than one valuable (and relatively heavy) mineral. Titanium minerals are found with a large range of titanium contents, giving rise to density variation and often subjective mineralogical descriptions. Companies tend to rely on laboratory heavy liquid separation in the evaluation of samples arising from exploration, mining or metallurgical processes. Unfortunately, there are only a limited number of high density (‘heavy’) liquids and these tend to be more toxic as their density increases. Low-toxicity inorganic solutions, based on tungsten compounds, have been developed that can be utilised at relative densities (RD) up to 3.0. However, beyond this value currently only organic liquids can be used. Diiodomethane (methylene iodide) having a relative density of 3.31 is commonly used; however, this presents significant health and safety hazards. Mixtures of thallium formate and thallium malonate were found in the early 1900s by Clerici to provide liquids having specific gravities between 4.0 and 5.0, hence ‘Clerici’s solution’. For the characterisation of the heavy components of mineral sand deposits (eg anatase sg 3.9, rutile sg 4.2, ilmenite sg 4.4 – 4.7 and zircon sg 4.6 – 4.8) there is currently no heavy liquid alternative to Clerici’s solution. Clerici’s solution is highly toxic and testing is now conducted by very few laboratories worldwide with costs reflecting the chemical costs (though extensive efforts are made to recover and reuse the liquid, plus the requirement of its removal from the mineral samples), the infrastructure costs and health and safety regimes (eg blood testing of exposed staff, inventory management). A simple laboratory technique of density fractionation is being developed, employing suspensions of fine tungsten carbide particles in lithium heteropolytungstate (LST) solutions, that can replace Clerici’s solution in the evaluation of fine mineral sands samples (eg -250+150 microns). The developing methodology that can achieve low-cost, low-toxic separations at relative densities above 5.0 will be outlined and the comparison of results with Clerici’s solution presented.
- Description: E1
- Description: 2003001621
Tectonic and economic implications of trace element, Ar-40/Ar-39 and Sm-Nd data from mafic dykes associated with orogenic gold mineralisation in central Victoria, Australia
- Authors: Bierlein, Frank , Hughes, Martin , Dunphy, J. , McKnight, Stafford , Reynolds, P. , Waldron, H.
- Date: 2001
- Type: Text , Journal article
- Relation: Lithos Vol. 58, no. 1-2 (Aug 2001), p. 1-31
- Full Text: false
- Reviewed:
- Description: Mafic to intermediate dykes are spatially and temporally closely associated with major post-tectonic granitic complexes in the western Lachlan Orogen of SE Australia. These dykes, which range petrographically from basaltic to andesitic, are concentrated within several, north- to northwest-trending zones and were emplaced during two broad intervals of extensive magmatic activity during the Silurian–Devonian period. Geochemical and Sm–Nd isotopic characteristics of these mafic intrusives are consistent with their formation in a complex subduction-related tectonic setting. Interaction between mantle-wedge material, sinking oceanic crust and input from the overlying continental crust resulted in the petrological and geochemical variations displayed by these and more felsic dykes throughout the study region. Field evidence and 40Ar/39Ar data show that in the eastern part of the Stawell Zone and in the northwest portion of the Bendigo Zone, mafic dyke were intruded between 410 and 400 Ma (Late Silurian/Early Devonian). Further emplacement in the Bendigo Zone and the eastern part of the Melbourne Zone took place at between 375 and 365 Ma (Middle to Late Devonian). Episodic mantle-derived magmatism was possibly related to step-wise rollback, slab detachment or changes in the angle and rate of westward subduction in response to periodically occurring accretionary pulses. A close spatial and temporal relationship also exists between the dykes and orogenic gold mineralisation in the central Victorian gold province. Mafic to intermediate dykes both crosscut, and are host to, mineralisation in a number of goldfields. Although there is little evidence for a direct genetic association, the two processes are linked by the common utilisation of translithospheric structures, which facilitated the rapid ascent into shallow crustal levels of both mantle-derived magma and crustal-scale ore-forming fluid systems. Previous studies have suggested that transfer of heat into the crust via ascending mafic mantle magmas can provide a thermal engine which triggers and sustains extensive crustal melting, thus explaining the commonly observed close association of mafic to intermediate and felsic intrusive suites. This study supports the viability of this mechanism and in addition, indicates that a causal link exists between the formation of mantle magmas in collisional zones and the generation of orogenic gold deposits.
- Description: C1
A diverse pleistocene marsupial trackway assemblage from the Victorian Volcanic Plains, Australia
- Authors: Carey, Stephen , Camens, Aaron , Cupper, Matthew , Grun, Rainer , Hellstrom, John , McKnight, Stafford , McLennan, Iain , Pickering, David , Trusler, Peter , Aubert, Maxime
- Date: 2011
- Type: Text , Journal article
- Relation: Quaternary Science Reviews Vol. 30, no. 5-6 (2011), p. 591-610
- Full Text: false
- Reviewed:
- Description: A diverse assemblage of late Pleistocene marsupial trackways on a lake bed in south-western Victoria provides the first information relating to the gaits and morphology of several megafaunal species, and represents the most speciose and best preserved megafaunal footprint site in Australia. The 60-110 ka volcaniclastic lacustrine sedimentary rocks preserve trackways of the diprotodontid Diprotodon optatum, a macropodid (probably Protemnodon sp.) and a large vombatid (perhaps Ramsayia magna or '. Phascolomys' medius) and possible prints of the marsupial lion, Thylacoleo carnifex. The footprints were imprinted within a short time period, demonstrating the association of the taxa present, rather than the time-averaged accumulations usually observed in skeletal fossil deposits. Individual manus and pes prints are distinguishable in some trackways, and in many cases some digital pad morphology is also present. Several parameters traditionally used to differentiate ichnotaxa, including trackway gauge and the degree of print in-turning relative to the midline, are shown to be subject to significant intraspecific variation in marsupials. Sexual dimorphism in the trackway proportions of Diprotodon, and its potential for occurrence in all large bodied, quadrupedal marsupials, is identified here for the first time. © 2010 Elsevier Ltd.
Hydrothermal insights into the deposition of invisible and visible gold within aresenopyrite
- Authors: Morey, A. , Tomkins, A. , Weinberg, R. , Bierlein, Frank , McKnight, Stafford , Davidson, G.
- Date: 2007
- Type: Text , Conference paper
- Relation: Proceedings of the Ninth Biennial SGA Meeting, Dublin 2007, 20th August, 2007 p. 781-784
- Full Text: false
- Description: By studying backscatter electron (BSE) micrographs, and the major- and trace-element geochemistry of gold bearing arsenopyrite from the late-Archaian Bardoc Tectonic Zone, Western Australia, this study helps constrain the hydrothermal conditions of gold deposition associated with this common ore mineral.
- Description: E1
- Description: 2003005489
Nature of gold mineralisation in the Walhalla Goldfield, southeast Australia
- Authors: Hough, M. A. , Bierlein, Frank , Ailleres, L. , McKnight, Stafford
- Date: 2010
- Type: Text , Journal article
- Relation: Australian Journal of Earth Sciences Vol. 57, no. 7 (2010), p. 969-992
- Full Text: false
- Reviewed:
- Description: The Walhalla-Woods Point Goldfield in southeast Australia is characterised by large gold deposits associated with a Late Devonian dyke swarm. The setting of this goldfield is unique because unlike the major gold deposits in Victoria, it occurs close to the eastern margin of the Western Lachlan Orogen, and highlights the disparities between the evolving phases of orogenic gold mineralisation in the Western Lachlan Orogen, and the contrasts between sediment hosted, dyke-associated and dyke-hosted gold mineralisation. This study integrates existing and new data from renewed mapping of the geology and geochemistry of three gold deposits near the township of Walhalla, in the historically important yet under-explored and under-researched Walhalla-Woods Point Goldfield. The ten highest yielding deposits within the goldfield are either hosted within, or adjacent to, intrusions of the Woods Point Dyke Swarm. This is due to the greater chemical reactivity of the calc-alkaline dykes, and the greater rheological contrast between the dykes and surrounding low-grade metasedimentary units, which allowed for the formation of dyke-hosted quartz breccia veins that are consistently favourable sites for gold mineralisation in the Walhalla Goldfield. This is in contrast to historical production, which concentrated on visible gold within the shear zone-hosted laminated quartz veins. Gold and As assay results have highlighted the increased levels of invisible gold disseminated along dyke margins in proximity to shear zones and quartz reefs. The high-yielding gold deposits hosted wholly by the dyke intrusions of the Woods Point Dyke Swarm are orogenic gold deposits, as they are not associated with elevated levels of Bi, W, As, Mb, Te and Sb, typical of intrusion-related gold deposits.
- Description: 2003008285
The role of carbonaceous "indicator" slates in the genesis of lode gold mineralization in the western Lachlan orogen, Victoria, southeastern Australia
- Authors: Bierlein, Frank , Cartwright, I. , McKnight, Stafford
- Date: 2001
- Type: Text , Journal article
- Relation: Economic Geology and the Bulletin of the Society of Economic Geologists Vol. 96, no. 3 (May-Jun 2001), p. 431-451
- Full Text: false
- Reviewed:
- Description: "Indicator" slates have long been considered to represent a useful exploration guide for turbidite-hosted mesothermal lode gold mineralization in central Victoria. This assumption has been based on an apparent close spatial relationship between high gold grades and the proximity of thin, commonly pyritic and carbon-rich marker units, Detailed studies in a number of gold deposits throughout central Victoria, however, reveal that highest gold grades do not necessarily coincide with the presence of carbonaceous units. In many places where gold mineralization is associated with carbon-rich matter, the high C accumulations are the result of epigenetic remobilization during hydrothermal alteration and ore genesis. Petrographic, geochemical, and stable isotope IC. O, Si investigations into the origin and nature of the carbonaceous matter-mainly amorphous bitumens and pyrobitumen of organic origin, with biological fragments and rare graphite of both detrital and metamorphic origin-demonstrate that black shales within the Cambro-Ordovician succession ill central Victoria lacked the vital constituents to provide (1) a primary sink for precious metals, and (2) whereas the presence of carbonaceous matter was likely to affect the evolution of epigenetic hydrothermal fluids and, locally, may have facilitated gold enrichment, carbon-rich sedimentary rocks were not crucial for ore genesis on the deposit scale. Instead, the size of the hydrothermal cell, physicochemical conditions of the ascending fluids, and dynamic fault-valve behavior played far more significant roles in controlling gold precipitation. The importance of these processes has implications for exploration targeting sediment-hosted, lode- and disseminated-style gold mineralization in the western Lachlan orogen and in slate belt provinces elsewhere.
- Description: C1
- Description: 2003002954
Recent research on black shale hosted base-metal deposit of the Mount Isa region, northern Australia
- Authors: Andy, Wilde , McKnight, Stafford
- Date: 2007
- Type: Text , Conference paper
- Relation: Ninth Biennial SGA Meeting, Dublin 2007, Dublin: Ireland p. 307-309
- Full Text: false
- Reviewed:
- Description: Recent research as part of the Co-operative Research Centre in Predictive Mineral Discovery has addressed a number of issues pertaining to the giant base-metal deposits of the Mount Isa Region of northern Australia.
- Description: E1
- Description: 2003005459
Leven Star deposit: An example of Middle to Late Devonian intrusion-related gold systems in the western Lachlan Orogen, Victoria
- Authors: Whittam, R. R. , Bierlein, Frank , McKnight, Stafford
- Date: 2006
- Type: Text , Journal article
- Relation: Australian Journal of Earth Sciences Vol. 53, no. 2 (2006), p. 343-362
- Full Text:
- Reviewed:
- Description: This study documents an example of atypical gold mineralisation in the central Victorian gold province of the western Lachlan Orogen, Australia. Unlike the vast majority of orogenic gold deposits in this region, the Leven Star deposit at Malmsbury is characterised by a disseminated-stockwork style of mineralisation, a close spatial and temporal association with post-tectonic felsic intrusions, complex alteration characteristics and a Au-As-Sb (±Bi-Te-Cu-Zn-Pb-Sn-W) ore assemblage. In contrast to orogenic-style, metamorphism-related gold mineralisation (ca 440 Ma), which pre-dated magmatism in the western Lachlan Orogen by tens of millions of years, ore formation in the Leven Star deposit was synchronous with, and is paragenetically younger than, Middle to Late Devonian (ca 370 Ma) magmatism. On the basis of these timing relationships, as well as whole-rock geochemistry, and structural, petrographic and fluid-inclusion data, it is suggested that the Leven Star deposit is not orogenic in character and instead should be classified as intrusion-related. © Geological Society of Australia.
- Description: C1
- Description: 2003001628
The biological oxidation of carbonaceous material in the treatment of a refractory gold bearing ore
- Authors: McKnight, Stafford , Hall, Stephen , Rowe, James
- Date: 2004
- Type: Text , Conference paper
- Relation: Paper presented at Refractory Gold Ore Bioxidation 2004, Bendigo, Victoria : 8th November, 2004
- Full Text: false
- Reviewed:
- Description: E1
- Description: 2003000721
Significance of monazite EPMA ages from the Quamby Conglomerate, Queensland
- Authors: Evins, P. M. , Wilde, A. R. , Foster, David , McKnight, Stafford , Blenkinsop, T. G.
- Date: 2007
- Type: Text , Journal article
- Relation: Australian Journal of Earth Sciences Vol. 54, no. 1 (2007), p. 19-26
- Full Text:
- Reviewed:
- Description: Th-U-Pb electron microprobe (EPMA) dating of mainly detrital monazite from the Quamby Conglomerate in the Eastern Succession of the Mt Isa inlier reveals three distinct monazite growth/recrystallisation events at around 1640, 1580 and 1490 Ma. These ages are particularly significant with respect to the timing of deposition, iron and gold mineralisation, and deformation in the Mt Isa inlier. The oldest age probably represents provenance from igneous rocks. In the sample, the majority of monazite growth occurred at 1580 Ma, coeval with peak metamorphism in the Eastern Succession. The low metamorphic grade of the conglomerate and wide compositional range of monazite bearing this age indicates that the monazite grew elsewhere and was later deposited in the conglomerate. Purple bands in the rock are composed mainly of coarse specular hematite with recrystallised margins that contribute to high (up to 20%) Fe2O3 contents in the conglomerate. Gold is also present in some of the samples. Some of the monazite grains contain small, younger (ca 1490 Ma) domains that may have grown/ recrystallised in situ during a lower grade syn- or post-diagenetic metamorphic/hydrothermal event that may have been related to hematite (re)crystallisation. Together, these ages bracket deposition of the Quamby Conglomerate to between ca 1580 and 1490 Ma, the latter age most likely representing diagenesis. This depositional age also represents a maximum age for north-south-striking, upright folds of the Quamby Conglomerate and implies that significant ductile deformation has affected parts of the Mt Isa inlier after 1580 Ma and probably after 1490 Ma.
- Description: C1
- Description: Creative work
- Description: 2003004832
Possible intrusion-related gold systems in the western Lachlan orogen, southeast Australia
- Authors: Bierlein, Frank , McKnight, Stafford
- Date: 2005
- Type: Text , Journal article
- Relation: Economic Geology Vol. 100, no. 2 (2005), p. 385-398
- Full Text:
- Reviewed:
- Description: Several gold deposits occurring in the western Lachlan orogen have geological, geochemical, and geochronological characteristics that distinguish them from typical vein-hosted orogenic gold deposits of the central Victorian gold province. The later are responsible for more than 90 percent, of primary (hard-rock) gold production from this region and are generally considered to represent the only economically significant type of gold deposit in the western Lach an orogen. Atypical gold occurrences at Malmsbury, Myrtle Creek, Mount Piper, and the Wonga deposit in the Stawell goldfield are characterized by a close spatial and temporal association with posttectonic felsic intrusions, disseminated to stockwork-style mineralization, alteration dominated by sericitization, sulfidation, silicification, carbonatization and tourmalinization, and associated complex An ± Mo-W-Bi-Te-Cu. The deposits have a number of features in common with intrusion-related gold deposits elsewhere in Phanerozoic orogenic belts. Although production from this type of gold mineralization in the western Lachlan orogen has been small compared to orogenic gold deposits, the possible existence of intrusion-related gold deposits has potentially important implications for exploration in this region and also provides significant clues to the tectonic framework and Paleozoic metallogeny of eastern Australia. © 2005 Society of Economic Geologists, Inc.
- Description: C1
- Description: 2003001065
Exploration tools for linked porphyry and epithermal deposits : Example from the mankayan intrusion-centered Cu-Au district, Luzon, Philippines
- Authors: Chang, Zhaoshan , Hedenquist, Jeffrey , White, Noel , Cooke, David , Roach, Michael , Deyell, Cari , Garcia Jr, Joey , Gemmell, J. Bruce , McKnight, Stafford , Cuison, Ana Liza
- Date: 2011
- Type: Text , Journal article
- Relation: Economic Geology Vol. 106, no. 8 (2011), p. 1365-1398
- Full Text: false
- Reviewed:
- Description: The Mankayan mineral district of northern Luzon, Philippines, hosts several significant ore deposits and prospects of various types within an area of ~25 km2, including the Far Southeast porphyry Cu-Au deposit, the Lepanto high sulfidation epithermal Cu-Au deposit, the Victoria intermediate sulfidation epithermal Au-Ag vein deposit, the Teresa epithermal Au-Ag vein deposit, the Guinaoang porphyry Cu-Au deposit, and the Buaki and Palidan porphyry Cu-Au prospects, all having formed in a period of about 2 m.y., from ~3 Ma. The geologic units include (1) a basement composed of Late Cretaceous to middle Miocene metavolcanic rocks and volcaniclastic rocks; (2) the Miocene 12 to 13 Ma tonalitic Bagon intrusive complex; (3) the Pliocene, ~2.2 to 1.8 Ma, Imbanguila dacite porphyry and pyroclastic rocks; and (4) postmineralization cover rocks, including the ~1.2 to 1.0 Ma Bato dacite porphyry and pyroclastic rocks and the ~0.02 Ma Lapangan tuff. Extensive advanced argillic alteration crops out for ~7 km along the unconformity between the basement rocks and the Imbanguila dacite formation and consists of quartz-alunite ± pyrophyllite or diaspore, with local zones of silicic alteration and a halo of dickite ± kaolinite. The alteration and its subhorizontal geometry indicate that it is a lithocap or coalesced lithocaps. The northwest-striking portion is ~4 km long and hosts the Lepanto enargite Au ore deposit, also controlled by the Lepanto fault. The Lepanto epithermal deposit is related to the underlying Far Southeast porphyry; the quartz-alunite alteration halo of Lepanto is contemporaneous with the ~1.4 Ma potassic alteration of the porphyry. There are also silicic-advanced argillic alteration patches ~600 m above the Far Southeast orebody at the present surface; these are interpreted to be perched alteration. There is no systematic mineralogical or textural zoning in the Lepanto lithocap that indicates direction to the intrusive source. Most surface samples of the lithocap contain less than 50 ppb Au, despite many being less than a few hundred meters from underground Cu-Au ore. This study found that several characteristics of the Lepanto lithocap change systematically with distance from the causative intrusion: The alunite absorption peak at ~1,480 nm in the short wavelength infrared (SWIR) spectrum shifts to higher wavelengths where the sample is closer to the intrusive center, due to higher Na and lower K content in the alunite; published experimental studies indicate that high Na/(Na + K) is related to higher formation temperature. High Ca alunite, including huangite, also occurs at locations proximal to the intrusive center. Alunite mineral composition analyzed by laser ablation-inductively coupled plasma-mass spectrometry (LA-ICP-MS) indicates that the Pb content decreases toward the intrusive center, whereas Sr, La, Sr/Pb, and La/Pb increase markedly. Whole-rock compositions, using only nonmineralized (taken as Cu <0.1wt % and Au <0.1 ppm) and alunite-bearing samples, show that Pb and Ag/Au, plus Hg and Ag, decrease toward the intrusive center, and Sr/Pb and La/Pb ratios increase. Normalizing whole-rock Pb to the (Na + K) molal content produces a proxy for the alunite mineral composition, and this ratio provides the same indications as the LA-ICP-MS analyses of alunite. The concealed Victoria epithermal veins consist of intermediate sulfidation mineralization on the southwest flank of the porphyry. The veins are not exposed, but their presence at depth is indicated by subtle alteration (illite or interstratified illite and/or smectite or smectite + pyrite) and geochemical (As, Se) anomalies at the surface. The anomalies are strongly dependent on erosion level; no anomalies were found where the surface is >~350 m above the upper extent of the veins. An airborne geophysics survey indicates that the Far Southeast orebody is associated with a wide zone of demagnetization due to extensive magnetite-destructive phyllic alteration. Such low magnetic anomalies on the margin of a large lithocap elsewhere may deserve att ntion. The directional indicators and mineralization signatures found in this study have the potential to indicate direction to the intrusive center during exploration of similar porphyryepithermal districts. ©2011 Society of Economic Geologists, Inc. Economic Geology.