Relationship of hydrothermal alteration to structure and stratigraphy at the Coniaurum gold mine, northern Ontario

Darwin W. Piroshco; C. Jay Hodgson

doi:10.1139/e88-189

Relationship of hydrothermal alteration to structure and stratigraphy at the Coniaurum gold mine, northern Ontario

Canadian Journal of Earth Sciences ◽

10.1139/e88-189 ◽

1988 ◽

Vol 25 (12) ◽

pp. 2028-2040

Author(s):

Darwin W. Piroshco ◽

C. Jay Hodgson

Keyword(s):

Hydrothermal Alteration ◽

Volcanic Rocks ◽

Shear Zones ◽

Wall Rock ◽

Gold Mine ◽

Northern Ontario ◽

Quartz Veins ◽

Mineral Assemblages ◽

Relationship Of ◽

Ore Zones

The gold mineralized zones of the Coniaurum mine, Porcupine camp, northeastern Ontario, are on the eastern end of the northeast-trending Hollinger–Mclntyre ore system. The ore zones are quartz–ankerite (plus accessories) veins and vein systems and associated pyritic wall rock, hosted by a sequence of mafic volcanic rocks and discordant quartz–feldspar porphyry stocks of Archean age.A least altered facies and three alteration facies can be distinguished within the mafic volcanic rocks: a chlorite facies, an ankerite facies, and a vein envelope facies. The chlorite facies is widespread, overprints the least altered facies (i.e., chlorite replaces actinolite), and hosts barren and locally mineralized quartz veins bordered by vein envelope facies alteration. The ankerite facies is coextensive with subparallel shear zones, which crosscut me axial trace of the Coniaurum anticline, and hosts most of the mineralized vein systems. Addition mineralization occurs within graphitic sediments in the crest area of the Coniaurum anticline.On the basis of the above relationships, the shear zones, hydrothermal alteration, and mineralization are interpreted to be late (i.e., syn- to post-development of the Coniaurum anticline).The mineral assemblages of the chlorite and ankerite alteration facies are interpreted as resulting from lateral gradients in [Formula: see text]. Replacement textures between minerals at the alteration facies boundaries indicate the hydrothermal system first grew outwards but later collapsed inwards and the vein envelope facies is superimposed on the more widespread ankerite and chlorite facies.

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Petrogenesis of amphibole – biotite – calcite – plagioclase alteration and laminated gold – silver quartz veins in four Archean shear zones of the Norseman district, Western Australia

Canadian Journal of Earth Sciences ◽

10.1139/e92-036 ◽

1992 ◽

Vol 29 (3) ◽

pp. 388-417 ◽

Cited By ~ 14

Author(s):

Andreas G. Mueller

Keyword(s):

Western Australia ◽

Shear Zones ◽

Wall Rock ◽

Alteration Zone ◽

Mining District ◽

Low Grade ◽

Fluid Temperature ◽

Quartz Veins ◽

The North ◽

Gold Silver

The Norseman mining district in the Archean Yilgarn Block, Western Australia, has produced 140 t of gold and about 90 t of silver from 11.24 × 106 t of ore. The district is located within a metamorphic terrane of mafic and minor ultramafic greenstones, intruded by granite cupolas and swarms of porphyry dykes. The orebodies consist of laminated quartz veins, controlled by narrow (0.5–5 m) reverse shear zones that, in general, follow the contacts of metapyroxenite or porphyry dykes. Petrological studies of four shear zones, exposed on the Regent shaft 14 level, Ajax shaft 10 level, and in the stope above the North Royal shaft 5 level, show that the host rocks were metamorphosed to hornblende–plagioclase amphibolites and actinolite–chlorite rocks at temperatures of 500–550 °C prior to mineralization.At the localities studied, intense wall-rock replacement and low-grade (0.5 g/t) gold mineralization are confined to ductile or brittle–ductile shear structures. Alteration is similar in both ultramafic and mafic greenstones, and consists of an inner zone of biotite–quartz–calcite–plagioclase rock with minor actinolitic hornblende and quartz–calcite–actinolite veinlets, and an outer zone, locally developed, of chlorite–calcite–quartz rock. At an estimated pressure of 3 kbar (300 MPa), fluid temperatures during wall-rock alteration are constrained by the hydrothermal mineral assemblages to 480 ± 30 °C in two shear zones on the Regent shaft 14 level, and to 450 ± 20 °C in one shear zone in the North Royal shaft 5 level stope. The mole fraction of CO2 of the fluids is estimated at [Formula: see text], and the sulphur fugacity at 10−6 bar (10−1 kPa) (at 450 °C), based on the assemblage pyrrhotite + pyrite ± arsenopyrite. The development of an outer chloritic alteration zone at North Royal is related to the lower fluid temperature at this locality.High-grade (up to 75 g/t Au, 283 g/t Ag) veins formed within three of the shear zones studied at fluid temperatures of 400 °C and less, by the successive accretion of quartz laminae, separated by films of retrograde chlorite and sericite. The assemblage of ore minerals in the veins differs from that in the altered wall rocks, and includes disseminated galena, Pb–Bi–Ag tellurides, and native gold, which coprecipitated with the quartz. The orebodies at Norseman show affinities to Phanerozoic and Archean gold skarn deposits.

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Hydrothermally altered volcanic rocks metamorphosed at granulite-facies conditions: an example from the Grenville Province

Canadian Journal of Earth Sciences ◽

10.1139/cjes-2016-0146 ◽

2017 ◽

Vol 54 (6) ◽

pp. 622-638 ◽

Cited By ~ 4

Author(s):

Marisa Hindemith ◽

Aphrodite Indares ◽

Stephen Piercey

Keyword(s):

Hydrothermal Alteration ◽

Volcanic Rocks ◽

Granulite Facies ◽

Metamorphic Overprint ◽

Grenville Province ◽

Rock Types ◽

Argillic Alteration ◽

New Findings ◽

Mineral Assemblages ◽

Liberation Analysis

A 1.2 Ga association of aluminous gneisses, garnetites, and white felsic gneisses of andesitic composition in the southern Manicouagan area (central Grenville Province) provides evidence consistent with protolith formation and hydrothermal alteration in a submarine volcanic environment. In addition to field relations, potential relics of quartz phenocrysts in the aluminous gneisses, revealed by SEM–MLA (scanning electron microscope with a mineral liberation analysis software) imaging, are consistent with a volcanic precursor. Moreover, in these rocks, aluminous nodules and seams of sillimanite are considered to represent metamorphosed hydrothermal mineral assemblages and to reflect former pathways of hydrothermal fluid. These features are preserved despite the Grenvillian granulite-facies metamorphic overprint and evidence of partial melting. In addition, the garnetites are inferred to represent hydrothermally altered products of the white gneisses, based on the gradational contacts between the two rock types. The compositional ranges of minerals are generally similar to those of granulite-facies metapelites, but moderately elevated contents of Mn in garnet from the garnetites, and Zn in spinel from the aluminous gneisses, are consistent with hydrothermal addition of these elements to the protolith. The most prominent alteration trends are an increase in Fe–Mg–Mn from the white gneisses to the aluminous gneisses and the garnetites, and a trend of increasing alumina index in some white gneisses, suggesting mild argillic alteration. The new findings highlight the preservation of early hydrothermal alteration in high-grade metamorphic belts in the Grenville Province, and these altered rocks are potential targets for exploration.

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Orogenic Gold in Transpression and Transtension Zones: Field and Remote Sensing Studies of the Barramiya–Mueilha Sector, Egypt

Remote Sensing ◽

10.3390/rs11182122 ◽

2019 ◽

Vol 11 (18) ◽

pp. 2122 ◽

Cited By ~ 17

Author(s):

Basem Zoheir ◽

Mohamed Abd El-Wahed ◽

Amin Beiranvand Pour ◽

Amr Abdelnasser

Keyword(s):

Remote Sensing ◽

Hydrothermal Alteration ◽

Gold Mineralization ◽

Shear Zones ◽

Island Arc ◽

Quartz Veins ◽

Vein Formation ◽

Time Space ◽

Band Ratioing ◽

Sentinel 2

Multi-sensor satellite imagery data promote fast, cost-efficient regional geological mapping that constantly forms a criterion for successful gold exploration programs in harsh and inaccessible regions. The Barramiya–Mueilha sector in the Central Eastern Desert of Egypt contains several occurrences of shear/fault-associated gold-bearing quartz veins with consistently simple mineralogy and narrow hydrothermal alteration haloes. Gold-quartz veins and zones of carbonate alteration and listvenitization are widespread along the ENE–WSW Barramiya–Um Salatit and Dungash–Mueilha shear belts. These belts are characterized by heterogeneous shear fabrics and asymmetrical or overturned folds. Sentinel-1, Phased Array type L-band Synthetic Aperture Radar (PALSAR), Advanced Space borne Thermal Emission and Reflection Radiometer (ASTER), and Sentinel-2 are used herein to explicate the regional structural control of gold mineralization in the Barramiya–Mueilha sector. Feature-oriented Principal Components Selection (FPCS) applied to polarized backscatter ratio images of Sentinel-1 and PALSAR datasets show appreciable capability in tracing along the strike of regional structures and identification of potential dilation loci. The principal component analysis (PCA), band combination and band ratioing techniques are applied to the multispectral ASTER and Sentinel-2 datasets for lithological and hydrothermal alteration mapping. Ophiolites, island arc rocks, and Fe-oxides/hydroxides (ferrugination) and carbonate alteration zones are discriminated by using the PCA technique. Results of the band ratioing technique showed gossan, carbonate, and hydroxyl mineral assemblages in ductile shear zones, whereas irregular ferrugination zones are locally identified in the brittle shear zones. Gold occurrences are confined to major zones of fold superimposition and transpression along flexural planes in the foliated ophiolite-island arc belts. In the granitoid-gabbroid terranes, gold-quartz veins are rather controlled by fault and brittle shear zones. The uneven distribution of gold occurrences coupled with the variable recrystallization of the auriferous quartz veins suggests multistage gold mineralization in the area. Analysis of the host structures assessed by the remote sensing results denotes vein formation spanning the time–space from early transpression to late orogen collapse during the protracted tectonic evolution of the belt.

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Kaolinization of the Kimolos Island volcanics, Cyclades, Greece

Clay Minerals ◽

10.1180/claymin.1989.024.1.07 ◽

1989 ◽

Vol 24 (1) ◽

pp. 75-89 ◽

Cited By ~ 1

Author(s):

P. Tsolis-Katagas ◽

M. Mavronichi

Keyword(s):

Hydrothermal Alteration ◽

Triple Point ◽

Volcanic Rocks ◽

Structural Disorder ◽

Intermediate Composition ◽

Mineral Assemblages ◽

Different Types ◽

Parent Rocks

AbstractPrimary kaolins, related to Pliocene-Pleistocene volcanic rocks of acid to intermediate composition from the southern part of Kimolos island contain kaolinite and quartz ± cristobalite. Smectite is rarely present whereas alunite is common and more prevalent than baryte or gypsum. The kaolinites show structural disorder (Hinckley indices ranging from 0·6 to 1·1) and contain faults along the c*-axis. The elements Nb, Th, Ce and Sr, La, V constitute two groups with a strong intercorrelation and the kaolins are enriched in these elements compared to the parent rocks. K, Rb, Y and Ba are positively correlated with feldspar content and decrease with the intensity of kaolinization. The mineral assemblages suggest a zonal pattern which is thought to be related to different types of hydrothermal alteration. Starting from the triple point of the alunite-K-feldspar-K-mica-quartz association encountered in Kimolos, a tentative path is presented showing the approximate ranges in concentrations of K2SO4 and H2SO4 required for the formation of the various mineral assemblages.

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Fluid chemistry and evolution of hydrothermal fluids in an Archaean transcrustal fault zone network: the case of the Cadillac Tectonic Zone, Abitibi greenstone belt, Canada

Canadian Journal of Earth Sciences ◽

10.1139/e06-130 ◽

2007 ◽

Vol 44 (6) ◽

pp. 745-773 ◽

Cited By ~ 12

Author(s):

P Neumayr ◽

S G Hagemann ◽

D A Banks ◽

B WD Yardley ◽

J -F Couture ◽

...

Keyword(s):

Hydrothermal Fluid ◽

Gold Mineralization ◽

Shear Zones ◽

Wall Rock ◽

Higher Order ◽

Hydrothermal Fluids ◽

Tectonic Zone ◽

Quartz Veins ◽

Hydrothermal Quartz ◽

Lower Fluid

Detailed fluid geochemistry studies on hydrothermal quartz veins from the Rouyn-Noranda and Val-d'Or areas along the transcrustal Cadillac Tectonic Zone (CTZ) indicate that unmineralized (with respect to gold) sections of the CTZ contained a distinct CO2-dominated, H2S-poor hydrothermal fluid. In contrast, both gold mineralized sections of the CTZ (e.g., at Orenada #2) and associated higher order shear zones have a H2O–CO2 ± CH4–NaCl hydrothermal fluid. Their CO2/H2S ratios indicate H2S-rich compositions. The Br/Cl compositions in fluid inclusions trapped in these veins indicate that hydrothermal fluids have been equilibrated with the crust. Oxygen isotope ratios from hydrothermal quartz veins in the CTZ are consistently 2 more enriched than those of associated higher order shear zones, which are interpreted to be a function of greater fluid/rock ratios in the CTZ and lower fluid/rock ratios, and more efficient equilibration of the hydrothermal fluid with the wall rock, in higher order shear zones. An implication from this study is that the lower metal endowment of the transcrustal CTZ, when compared with the higher metal endowment in higher order shear zones (ratio of about 1 : 1000), may be the result of the lack of significant amounts of H2O–H2S rich fluids in most of the CTZ. In contrast, gold mineralization in the higher order shear zones appear to be controlled by the high H2S activity of the aqueous fluids, because gold was likely transported in a bisulfide complex and was deposited during sulfidation reactions in the wall rock and phase separation in the quartz veins.

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Origin and Characteristics of the Shwetagun Deposit, Modi Taung-Nankwe Gold District and the Kunzeik and Zibyaung Deposits, Kyaikhto Gold District in Mergui Belt, Myanmar: Implications for Fluid Source and Orogenic Gold Mineralization

Frontiers in Earth Science ◽

10.3389/feart.2021.772083 ◽

2021 ◽

Vol 9 ◽

Author(s):

Myo Kyaw Hlaing ◽

Kotaro Yonezu ◽

Khin Zaw ◽

Aung Zaw Myint ◽

May Thwe Aye ◽

...

Keyword(s):

Native Gold ◽

Gold Mineralization ◽

Shear Zones ◽

Wall Rock ◽

Gold Deposits ◽

Orogenic Gold ◽

Salinity Range ◽

Quartz Veins ◽

Economic Significance ◽

Gold Bearing

The Mergui Belt of Myanmar is endowed with several important orogenic gold deposits, which have economic significance and exploration potential. The present research is focused on two gold districts, Modi Taung-Nankwe and Kyaikhto in the Mergui Belt comparing their geological setting, ore and alteration mineralogy, fluid inclusion characteristics, and ore-forming processes. Both of the gold districts show similarities in nature and characteristics of gold-bearing quartz veins occurring as sheeted veins, massive veins, stockworks to spider veinlets. These gold deposits are mainly hosted by the mudstone, slaty mudstone, greywacke sandstone, slate, and slaty phyllite of Mergui Group (dominantly of Carboniferous age). The gold-bearing quartz veins generally trend from NNE to N-S, whereas some veins strike NW-SE in all deposits. The gold-bearing quartz veins are mainly occurred within the faults and shear zones throughout the two gold districts. Wall-rock alterations at Shwetagun are mainly silicification, chloritization, and sericitization, whereas in Kyaikhto, silicification, carbonation, as well as chloritization, and sericitization are common. At Shwetagun, the gold occurred as electrum grains in fractures within the veins and sulfides. In Kyaikhto, the quartz-carbonate-sulfide and quartz-sulfide veins appeared to have formed from multiple episodes of gold formation categorizing mainly as free native gold grains in fractures within the veins or invisible native gold and electrum within sulfides. At Shwetagun, the ore minerals in the auriferous quartz veins include pyrite, galena, and sphalerite, with a lesser amount of electrum, chalcopyrite, arsenopyrite, chlorite, and sericite. In Kyaikhto, the common mineralogy associated with gold mineralization is pyrite, chalcopyrite, sphalerite, galena, pyrrhotite, arsenopyrite, marcasite, magnetite, hematite, ankerite, calcite, chlorite, epidote, albite, and sericite. At Shwetagun, the mineralization occurred at a varying temperature from 250 to 335°C, with a salinity range from 0.2 to 4.6 wt% NaCl equivalent. The Kyaikhto gold district was formed from aqueous–carbonic ore fluids of temperatures between 242 and 376°C, low to medium salinity (<11.8 wt% NaCl equivalent), and low CO2 content. The ore-forming processes of the Shwetagun deposit in the Modi Taung-Nankwe gold district and the Kyaikhto gold district are remarkably comparable to those of the mesozonal orogenic gold systems.

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Detection of slip surface in earth slide based on mineral assemblages -An example of hydrothermal alteration zone landslide in East Hokkaido Japan-

Journal of the Japan Landslide Society ◽

10.3313/jls.51.26 ◽

2014 ◽

Vol 51 (3) ◽

pp. 106-112

Author(s):

Hiroyuki MAEDA ◽

Masanori KOHNO ◽

Yoshihiko SEKISHITA ◽

Satoshi UEMATSU ◽

Hiroshi NAYA

Keyword(s):

Hydrothermal Alteration ◽

Slip Surface ◽

Alteration Zone ◽

Mineral Assemblages

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Mafic igneous rocks and mineralisation in the Palaeoproterozoic Ketilidian orogen, South-East Greenland: project SUPRASYD 1996

Geological Survey of Denmark and Greenland Bulletin ◽

10.34194/ggub.v176.5064 ◽

1997 ◽

pp. 66-74

Author(s):

Henrik Stendal ◽

Wulf Mueller ◽

Nicolai Birkedal ◽

Esben I. Hansen ◽

Claus Østergaard

Keyword(s):

Mineral Exploration ◽

Volcanic Rocks ◽

Shear Zones ◽

Field Work ◽

Igneous Rocks ◽

Border Zone ◽

The South ◽

East Greenland ◽

North West ◽

Arc Setting

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Stendal, H., Mueller, W., Birkedal, N., Hansen, E. I., & Østergaard, C. (1997). Mafic igneous rocks and mineralisation in the Palaeoproterozoic Ketilidian orogen, South-East Greenland: project SUPRASYD 1996. Geology of Greenland Survey Bulletin, 176, 66-74. https://doi.org/10.34194/ggub.v176.5064 _______________ The multidisciplinary SUPRASYD project (1992–96) focused on a regional investigation of the Palaeoproterozoic Ketilidian orogenic belt which crosses the southern tip of Greenland. Apart from a broad range of geological and structural studies (Nielsen et al., 1993; Garde & Schønwandt, 1994, 1995; Garde et al., 1997), the project included a mineral resource evaluation of the supracrustal sequences associated with the Ketilidian orogen (e.g. Mosher, 1995). The Ketilidian orogen of southern Greenland can be divided from north-west to south-east into: (1) a border zone in which the crystalline rocks of the Archaean craton are unconformably overlain by Ketilidian supracrustal rocks; (2) a major polyphase pluton, referred to as the Julianehåb batholith; and (3) extensive areas of Ketilidian supracrustal rocks, divided into psammitic and pelitic rocks with subordinate interstratified mafic volcanic rocks (Fig. 1). The Julianehåb batholith is viewed as emplaced in a magmatic arc setting; the supracrustal sequences south of the batholith have been interpreted as either (1) deposited in an intra-arc and fore-arc basin (Chadwick & Garde, 1996), or (2) deposited in a back-arc or intra-arc setting (Stendal & Swager, 1995; Swager, 1995). Both possibilities are plausible and infer subduction-related processes. Regional compilations of geological, geochemical and geophysical data for southern Greenland have been presented by Thorning et al. (1994). Mosher (1995) has recently reviewed the mineral exploration potential of the region. The commercial company Nunaoil A/S has been engaged in gold prospecting in South Greenland since 1990 (e.g. Gowen et al., 1993). A principal goal of the SUPRASYD project was to test the mineral potential of the Ketilidian supracrustal sequences and define the gold potential in the shear zones in the Julianehåb batholith. Previous work has substantiated a gold potential in amphibolitic rocks in the south-west coastal areas (Gowen et al., 1993.), and in the amphibolitic rocks of the Kutseq area (Swager et al., 1995). Field work in 1996 was focused on prospective gold-bearing sites in mafic rocks in South-East Greenland. Three M.Sc. students mapped showings under the supervision of the H. S., while an area on the south side of Kangerluluk fjord was mapped by H. S. and W. M. (Fig. 4).

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