Characterization and modeling of illite crystal particles and growth mechanisms in a zoned hydrothermal deposit, Lake City, Colorado

Bove, Dana J.; Eberl, Dennis D.; McCarty, Douglas K.; Meeker, Gregory P.

doi:10.2138/am-2002-11-1204

Cited by 34 publications

(13 citation statements)

References 19 publications

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“…The phengitic composition of the pure illite phase is comparable with a number of low temperature illites formed under a range of diagenetic, low temperature metamorphic and hydrothermal conditions (Hunziker et al 1986;Bove et al 2002;Inoue et al 2004). Yoder and Eugster (1955) and Velde (1965) determined that the 1M d fi 2M 1 white mica transformation occurs experimentally in the temperature range of 125°C (400 MPa) to 350°C, and in natural prograde metamorphic sequences this transition occurs predominantly under anchizonal conditions (200-300°C) and is complete by the beginning of the greenschist facies (Frey 1987).…”

Section: Hydrothermal Illitization Of Feldsparssupporting

confidence: 55%

Fluid focusing and back-reactions in the uplifted shoulder of the Rhine rift system: a clay mineral study along the Schauenburg Fault zone (Heidelberg, Germany)

Schleicher

Warr²,

Pluijm

2005

Int J Earth Sci (Geol Rundsch)

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A retrograde sequence of fluid-controlled, lowtemperature mineral reactions has been preserved along an east-west striking, dextral-oblique-slip fault in the uplifted Rhine Graben shoulder. This fault (the Schauenburg Fault, near Heidelberg), juxtaposes Permian rhyolite against Carboniferous (Variscan) granite and shows syn-or post-rift displacement of the north-south trending, eastern boundary fault of the rift basin. Both mineral texture and rock fabric indicate that the fault forms a site of high rock permeability and fluid flow, and records the exhumation and fluid-rock history of the rift shoulder since the Mesozoic. The reaction sequence and mineral compositions of the clay minerals within the cataclasite, and adjacent granite and rhyolite lithologies, document progressively decreasing fluid temperatures, with back-reactions of pure 2M 1 illite to 1M d (R3) illite-smectite, and eventually smectite and kaolinite assemblages. Compositional variations are attributed to Tertiary to Recent fluid flushing of the fault zone associated with rift flank uplift, and with progressive dilution of the electrolyte-rich, acidic to neutral hydrothermal brines by down-flowing electrolyte-poor, meteoric waters.

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Section: Hydrothermal Illitization Of Feldsparssupporting

confidence: 55%

Fluid focusing and back-reactions in the uplifted shoulder of the Rhine rift system: a clay mineral study along the Schauenburg Fault zone (Heidelberg, Germany)

Schleicher

Warr²,

Pluijm

2005

Int J Earth Sci (Geol Rundsch)

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“…Indeed, it is well documented that in shallow crustal environments like the one inferred here for Bouskour ore deposition, exsolution of hydrothermal fluids from a crystallizing magma can release large volumes of gases, including oxidizing components such as SO 2(g) , acidic components such as HCl (g) , and smaller volumes of dense, saline brines (Bodnar et al 1985). The occurrence of acidic fluid conditions during emplacement of the copper mineralization at Bouskour is supported by the coexistence of illite-chlorite alteration assemblages (see Hedenquist and Browne 1989;Bove et al 2002).…”

Section: Discussionmentioning

confidence: 97%

Re/Os Age Determination, Lead and Sulphur Isotope Constraints on the Origin of the Bouskour Cu–Pb–Zn Vein-Type Deposit (Eastern Anti-Atlas, Morocco) and Its Relationship to Neoproterozoic Granitic Magmatism

Bouabdellah

Maacha²,

Jébrak³

et al. 2016

Mineral Deposits of North Africa

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The newly re-evaluated Bouskour deposit is a large, polymetallic vein-type system in the Precambrian Sidi Flah-Bouskour inlier of the eastern Anti-Atlas orogen. Resources are >53 Mt at 0.8 % Cu, of which 21 Mt has a higher grade of 1.3 % Cu and 9 g/t Ag. Host rocks are assigned to the Ediacaran Ouarzazate Group, and consist of a succession of mafic-ultramafic to felsic igneous rocks, both intrusive and extrusive, with ages ranging from 570 ± 5 to 557 ± 5 Ma, partly intruding Cryogenian basalt and andesite. Among these igneous bodies, intrusive felsic rocks are by far the most abundant lithologies, consisting of three elongate, NW-SE-trending, calc-alkaline intrusions referred to as: (1) Bouskour Granodiorite, (2) Bouskour Granite dated at 570 ± 5 Ma, and (3) system of red to white aphanitic rhyolite locally known as the "Bouskour rhyolitic dike swarm" intruded all older units at 564 ± 7 to 562 ± 5 Ma. Cu-Pb-Zn sulphide mineralization produced an array of five transtensional, N-S and ENE-to NNW-trending vein systems referred to as "Filon Principal," "Filon Ouest," "Filon I," "Filon II," and "Filon Camra." The veins are up to 20 m wide and extend laterally from a few hundred meters to more than 10 km, spaced 50 to >1000 m apart, striking predominantly N160°E with steep dips (70°to *90°). Characteristic are comb, cockade, laminated, breccia, and crack and seal textures, suggesting that episodic mechanisms were important in vein formation. Sulphide minerals consist predominantly of various proportions of chalcopyrite, bornite, galena, sphalerite, pyrite, and arsenopyrite, with subordinate tetrahedritetennantite, magnetite, cassiterite, and rutile. The hydrothermal alteration assemblage comprises sericite, epidote, chlorite, quartz, and carbonates (calcite, dolomite). Three successive stages of ore deposition are recognized. The earliest stage (I) is referred to as "Cu-Zn-(Fe-As-CoBi-Sn) stage" is followed by the main Cu-Pb-Zn sulphide stage (II), which accounts for most of the exploited sulphide ore at Bouskour. The latest stage (III) forms late fillings in calcite or quartz veins or within older stage I and II assemblages, and includes Au-Ag-Cu-(Zn-Pb) mineralization. New 187 Re/ 188 Os age dating of a single molybdenite crystal from stage II yields an age of 574.9 ± 2.4 Ma. This age coincides, within analytical uncertainty, with a SHRIMP U-Pb age on zircon from the Bouskour Granite. The age correspondence suggests a foremost role of granite-derived hydrothermal fluids in the genesis of this polymetallic vein system, consistent with sulphur and lead isotopic data. This timing of mineralization relates to the final, post-collision extensional stage of the Pan-African orogeny.

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“…The than a pressure effect (e.g., Sassi and Scolari, 1974;Guidotti and Sassi, 1986 (Shirozu and Higashi, 1972;Meunier and Velde, 1982;Inoue et al, 1987Inoue et al, , 1988Drits et al, 1993;Inoue and Kitagawa, 1994;Drews-Armitage et al, 1996;Celik et al, 1999;Yan et al, 2001;Bove et al, 2002;Schleicher, 2006).…”

Section: Mineralogymentioning

confidence: 99%

Illite occurrences related to volcanic-hosted hydrothermal mineralization in the Biga Peninsula, NW Turkey: Implications for the age and origin of fluids

Bozkaya

Uysal

et al. 2016

Ore Geology Reviews

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Characterization and modeling of illite crystal particles and growth mechanisms in a zoned hydrothermal deposit, Lake City, Colorado

Cited by 34 publications

References 19 publications

Fluid focusing and back-reactions in the uplifted shoulder of the Rhine rift system: a clay mineral study along the Schauenburg Fault zone (Heidelberg, Germany)

Fluid focusing and back-reactions in the uplifted shoulder of the Rhine rift system: a clay mineral study along the Schauenburg Fault zone (Heidelberg, Germany)

Re/Os Age Determination, Lead and Sulphur Isotope Constraints on the Origin of the Bouskour Cu–Pb–Zn Vein-Type Deposit (Eastern Anti-Atlas, Morocco) and Its Relationship to Neoproterozoic Granitic Magmatism

Illite occurrences related to volcanic-hosted hydrothermal mineralization in the Biga Peninsula, NW Turkey: Implications for the age and origin of fluids

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