Hydrothermal alteration in metasedimentary rock-hosted orogenic gold deposits, Reefton goldfield, South Island, New Zealand

Christie, Anthony B.; Brathwaite, Robert L.

doi:10.1007/s00126-002-0280-9

Cited by 74 publications

(40 citation statements)

References 25 publications

(30 reference statements)

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“…1) had ore with high arsenopyrite content and little pyrite (Christie & Brathwaite 2003). The historic Prohibition Roasting Plant site, at Waiuta mine, has high levels of As in mine waste, including solids with As up to 40 wt% and high dissolved As (up to 70 mg/L) in associated waters (Haffert & Craw 2008b).…”

Section: Geological Backgroundmentioning

confidence: 99%

Adsorption of arsenic by iron rich precipitates from two coal mine drainage sites on the West Coast of New Zealand

Rait¹,

Trumm²,

Pope³

et al. 2010

New Zealand Journal of Geology and Geophysics

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Dissolved As can be strongly adsorbed to fine grained Fe(III) minerals such as hydroxides, oxyhydroxides and hydroxysulphates. Therefore precipitates that form during neutralisation or treatment of acid mine drainage have potential to be useful for treatment of As-contaminated water because acid mine drainage is often Fe rich. We tested the adsorption properties of Fe(III) rich precipitates from two West Coast coal mines with As-contaminated water from an historic gold ore processing site near Reefton. Precipitates were collected from distinctly different settings, an active acid mine drainage treatment plant at Stockton mine and the neutralisation/oxidation zone of acid mine drainage discharge at the abandoned Blackball Coal Mine. The two mine sites produce precipitates with different compositions and mineralogy. Arsenic adsorption onto precipitates from each site was determined in batch and column tests under laboratory conditions. Batch experiments indicate As adsorption occurs rapidly during the first 5 h and reaches equilibrium after 24 h. At equilibrium, and for a dosing ratio of 50 g of precipitate per litre of water, As concentrations decreased from 99 mg/L to 0.0080 mg/L with precipitates from Stockton and to 0.0017 mg/L with precipitates from Blackball. Arsenic adsorption capacity is up to 12 mg/g on precipitates from Stockton sludge and 74 mg/g on precipitates from Blackball. The Blackball precipitate adsorbs more As than precipitates from Stockton which is probably due to the higher Fe oxide content but pH and surface structure could also play a role. The column experiment confirmed that adsorption of As from a continuous waste stream onto these precipitates is possible, and that passive remediation using this waste product mixed with gravel to enhance permeability could be a viable approach at As-contaminated mine sites.

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Section: Geological Backgroundmentioning

confidence: 99%

Adsorption of arsenic by iron rich precipitates from two coal mine drainage sites on the West Coast of New Zealand

Rait¹,

Trumm²,

Pope³

et al. 2010

New Zealand Journal of Geology and Geophysics

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“…The model can be applied to similar tectonic settings, e.g., East Shandong , Tien Shan (Chen et al, 2000a;Rui et al, 2002;Zhang et al, 2003), Altay Shan ), Hinggan Range , Lachlan Fold Belt (Bierlein and Maher, 2001), European Alpine Belt (Kilais and Konnerup-Madsen, 1997;Boorder et al, 1998;Pettke et al, 1999Pettke et al, , 2000, the South Island of New Zealand (Brathwaite and Pirajno, 1993;Christie and Brathwaite, 2003) and Nova Scotia of Canada (Christie et al, 2001). …”

Section: Tectonic-metallogenic Model: Ore Genesismentioning

confidence: 99%

Ore Geology, Fluid Geochemistry and Genesis of the Shanggong Gold Deposit, Eastern Qinling Orogen, China

Chen

Pirajno

et al. 2006

Resource Geology

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. The Shanggong Au deposit in the Xiong'er Terrane, East Qinling, has reserves of about 30 t Au, making it one of the largest orogenic‐type Au deposits hosted in volcanic rocks in China. The deposit is hosted in the andesitic assemblage of the Xiong'er Group of 1.85˜1.4 Ga. Three stages of hydrothermal ore‐forming processes are recognized, Early (E), Middle (M) and Late (L), characterised by quartz‐pyrite, polymetallic sulfides and carbonate‐quartz, respectively. Homogenization temperatures of fluid inclusions are between 380‐320d̀C for the E‐stage, 300‐220d̀C for the M‐stage and 200‐120d̀C for the L‐stage. The composition of fluid inclusions changed from CO2‐rich in the E‐stage to CO2‐poor L‐stage. The M‐stage fluid has the highest contents of cations and anions (e.g., SO42‐, Cl1, K+), the highest (K+Na)/(Mg+Ca) and lowest CO2/H2O ratios, which probably resulted from CO2 phase separation. This, together with the alkaline and reducing conditions, as indicated by highest pH and lowest Eh values, is most conducive to the deposition of polymetallic sulfides and native elements such as Au, Ag and Te. H‐O isotope systematics indicate that ore fluids evolved from deep‐sourced through to shallow‐sourced, with the M‐stage being a mixing phase of these two fluid‐systems. Nineteen δ18OW values, from 4.2 to 13.4 %o, averaging 8.1 %o, suggest that the E‐stage fluids derived from metamorphic devolatilization of sedimentary rocks at depth. Comparison of the H‐O isotope systematics between the Shanggong deposit and the main lithologies in the Xiong'er Terrane, shows that neither these nor the underlying lower crust and mantle, or combinations thereof, could be considered as the source of ore fluids and metals for the Shanggong Au deposit. Instead, a source which meets the isotopic constraints, is a carbonaceous carbonate‐sandstone‐shale‐chert (CSC) sequence, which is present in the Guandaokou and Luanchuan Groups in the south of the Xiong'er Terrane. This conclusion is supported by thirteen high δ18O values of the Meso‐Neoproterozoic strata south of the Machaoying fault, and the high δ18OW values calculated for their possibly metamorphic fluids. It can be also supported by previous observation that the Guandaokou and Luanchuan Groups were underthrust beneath the Xiong'er Terrane, during the Mesozoic collision between the Yangtze and Sinokorean continents. Available isotope ages, together with geological field data, constrain the timing of the Au metallogenesis between 250˜110 Ma. This metallogenesis and associated granitic magmatism, can be related to the Yangtze‐Sinokorean continental collision that resulted in the formation of the Qinling Orogen. This collision event progressed from early compression (Triassic to Early Jurassic), through middle compression‐to‐extension transition (Late Jurassic to Early Cretaceous), to late extension (Cretaceous). These three stages in the evolution of the Qinling Orogen form the basis of an ore genesis model that combines collisional orogeny, metallogeny and fluid flow (CMF model). ...

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“…West of the mountains, the rocks are predominantly Paleozoic, and include a suite of Ordovician metasedimentary rocks, the Greenland Group, that host gold-bearing fault systems (Christie & Brathwaite 2003). Mesozoic metasedimentary rocks dominate to the east of the mountains, and these are locally mineralised with gold-bearing fault systems as well.…”

Section: Introductionmentioning

confidence: 99%

Climatic and compositional controls on secondary arsenic mineral formation in high-arsenic mine wastes, South Island, New Zealand

Haffert

Craw

Pope

2010

New Zealand Journal of Geology and Geophysics

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Recent and historic gold mines and mine wastes in the South Island of New Zealand have been exposed under a wide range of climatic conditions for up to 100 yr. The studied sites are in rain shadow areas east of the Southern Alps, and in wet areas west of the mountains. Arsenic concentrations in mine wastes are up to 20 wt% locally. The arsenic is primarily derived from arsenopyrite in gold-bearing ore, although roasting and oxidation of ore occurred at some mines. Arsenolite was a byproduct of roasting at two sites, and this was also discharged into mine wastes. Five secondary As minerals, scorodite, kankite, pharmacosiderite, zykaite, and bukovskyite, have formed in different mines and mine wastes during surficial oxidation and remobilisation. The minerals formed under different chemical and climatic conditions. Ferrihydrite with combined arsenate (up to 20 wt% As) occurs at all localities. Scorodite is the most common secondary As mineral, replacing arsenopyrite and/or arsenolite, and forming cement in mine wastes. Dissolution and precipitation of scorodite, which is strongly pH dependent, controls maximum dissolved As concentrations on a regional scale. Kankite has formed instead of scorodite in a persistently moist microclimate east of the mountains. Pharmacosiderite formed instead of scorodite on the 50 yr time-scale in mine tunnels at pH 7Á8. Pharmacosiderite is distinctly less soluble than scorodite in this groundwater setting at pH 7Á8, and apparently restricts dissolved As to B25 mg/L locally. Bukovskyite and zykaite form where dissolved sulfate concentrations are elevated and the host mine wastes are perennially damp.

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Hydrothermal alteration in metasedimentary rock-hosted orogenic gold deposits, Reefton goldfield, South Island, New Zealand

Cited by 74 publications

References 25 publications

Adsorption of arsenic by iron rich precipitates from two coal mine drainage sites on the West Coast of New Zealand

Adsorption of arsenic by iron rich precipitates from two coal mine drainage sites on the West Coast of New Zealand

Ore Geology, Fluid Geochemistry and Genesis of the Shanggong Gold Deposit, Eastern Qinling Orogen, China

Climatic and compositional controls on secondary arsenic mineral formation in high-arsenic mine wastes, South Island, New Zealand

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