Quantifying chemical changes in hydrothermally altered volcanic sequences — silica enrichment as a guide to the crandon massive sulfide deposit, Wisconsin, U.S.A.

Lavery, Norman G.

doi:10.1016/0375-6742(85)90002-0

Cited by 16 publications

(5 citation statements)

References 16 publications

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“…The development of siliceous rock bodies in and on the kaolinite deposit indicates advancing hydrothermal alteration activity. Thus, the silica released during the kaolinization process was concentrated within injecting acidic hydrothermal fluids and mixed with meteoric water, thus resulting in the development of silica veins coprecipitated with blocky kaolinite in fine-grained kaolinized units, and in several irregular silica lenses and a silica cap (consisting of fine-and coarse-grained quartz and cristobalite) within and above the kaolinite deposit, respectively, similar to the situations reported by Lavery (1985) and Inoue (1995). Thin-section determinations reveal that plagioclase is kaolinized, hornblende and biotite are opacitized, and that Fe-oxide/-hydroxide and silica phases have developed.…”

Section: Discussionsupporting

confidence: 74%

“…The line for kaolinite weathering is from Savin & Epstein (1970) and the line S/H for supergene/hypogene is from Sheppard et al (1969). (Figs 1 and 2) (Nagasawa, 1978;Gibson et al, 1983;Lavery, 1985;Inoue, 1995). This suggestion is also supported by the development of reddish-brownish colouration and the precipitation of quartz and Fe-oxide/hydroxide-and S-phases, such as goethite + lepidocrocite + hematite + pyrite + marcasite + jarosite + alunite, in an acidic-reducing open system in microfractures and veins that cross-cut the kaolinite deposit and in microfaults and fractures in the Kozören area outside of the deposit (Schwertmann, 1993;Kämpf et al, 2000;Meunier, 2005).…”

Section: Discussionmentioning

confidence: 99%

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Mineralogy, micromorphology, geochemistry and genesis of a hydrothermal kaolinite deposit and altered Miocene host volcanites in the Hallaçlar area, Uşak, western Turkey

Erkoyun¹,

Kadır²

2011

Clay miner.

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The Hallaçlar kaolinite deposit of the Uşak Province (western Turkey) is hosted by dacite, andesite and siliceous materials of the Miocene Karaboldere volcanites. Mineralogical zonation, such as the prevalence of kaolinite at the centre of the deposit, coexisting with silica polymorphs such as quartz and cristobalite along with feldspar and hornblende, and a relative increase of smectite, illite, chlorite, and Fe-oxide/-hydroxide phases outward and upward, demonstrate that hydrothermal-alteration processes resulted in kaolinization. Micromorphologically, kaolinite occurs as pseudohexagonal blocky kaolinite with coarse-grained quartz in microfractures, and the presence of relatively fine-grained vermiform kaolinite that edges volcanic materials indicates that kaolinite developed in several phases coexisting with goethite, lepidocrocite, hematite, pyrite, jarosite, alunite, and gypsum/anhydrite with smectite in fractures. The highly crystallized Hallaçlar kaolinite is identified by: (1) sharp reflections at 7.23 and 3.57 Å, with triplet and doublet non-basal reflections; (2) sharp infrared spectral bands at 3687, 3651 and 3620 cm-1; (3) well defined, pseudohexagonal and hexagonal kaolinite crystal growth; (4) a chemical index of weathering of 98.6-100; and (5) SiO2/Al2O3 ratios between 1.04 and 1.45. Enrichment of Sr and depletion of Rb+Ba, Ti, and HREE relative to LREE, with a distinct negative Eu anomaly, are responses to the fractionation of feldspar and hornblende by the hydrothermal fluid; these results are also supported by the O- and H-isotopic character and formation temperatures of the Hallaçlar kaolinite and smectite; namely, 134.1-183.4°C and 65.6°C, respectively. The negative δ34S (-20.7‰) value of gypsum/anhydrite reflects its formation from geothermal-water-derived sulphur. Under the influence of a tectonically controlled hydrothermal process, feldspar, hornblende and volcanic glass were altered, resulting in the conservation of Al and depletion of Si, Na, Ca, K, Mg and Fe in an open hydrological system such that formation of kaolinite in the central part of the deposit under acidic conditions and development of smectite and illite upward and outward under basic conditions were favoured.

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Section: Discussionsupporting

confidence: 74%

Section: Discussionmentioning

confidence: 99%

Mineralogy, micromorphology, geochemistry and genesis of a hydrothermal kaolinite deposit and altered Miocene host volcanites in the Hallaçlar area, Uşak, western Turkey

Erkoyun¹,

Kadır²

2011

Clay miner.

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“…Siliceous explosion cones, with silicified angular blocks and silicified zones (siliceous caps), comprise a highly altered outcrop around the kaolinite deposits, and apparently developed due to volcanic blasts and hydrothermal filling ( Fig. 11; Iwao, 1968;Gibson et al, 1983;Lavery, 1985;Morton & Franklin, 1987;Sayın, 2007). Development of silicified cone structures on kaolinized tuff and other aspects mentioned above, suggest strongly acidic hydrothermal activity.…”

Section: Fig 11 Genetic Model For the Tas°oluk Kaolinite Depositsmentioning

confidence: 99%

Mineralogy, geochemistry and genesis of the Taşoluk kaolinite deposits in pre-Early Cambrian metamorphites and Neogene volcanites of Afyonkarahisar, Turkey

Kadır¹,

Akbulut²

2009

Clay miner.

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Editor: John Adams)AB ST R ACT : The Tas°oluk kaolinite deposits of Afyonkarahisar (western Anatolia) are hosted by both pre-Early Cambrian sericitic mica-chlorite schists and Neogene volcanites, the latter comprising tuffs and agglomerates. These units have been affected by hydrothermal alteration controlled by faults resulting in complex, irregular, lateral mineralogical zonation. The occurrence of a siliceous cap on altered schists and in claystone, of quartz veins in schists and tuffs, and the development of explosion cones and pit fillings indicate that alteration in both the schists and the volcanites is due to hydrothermal processes. Altered schists have generally large (locally small) Fe contents, and claystones are generally silicified and have small Fe contents. Kaolinite predominates south and west of Tas°oluk, whereas high (Fe+Ti)-bearing illite + kaolinite predominate in other altered sections. The kaolinite exhibits a stacked micromorphology within altered schists, and the altered volcanites record in situ precipitation, derived from a mechanism of paired dissolution and precipitation. Illite fibres coexist with kaolinite, smectite, chlorite, mica and sericitized feldspar in markedly altered schists, revealing that the illite formed either authigenically or by conversion of smectite to illite. A relative increase in Cr+Ni and decrease in Sr+Ba in the kaolinite deposits and their schistose host rock relative to the upper level of the kaolinite deposits and their volcanic parent rocks came about by the alteration of chlorite, mica and feldspar in the sericitic mica-chlorite schists, and feldspar, glass shards and schist fragments in the volcanites as a result of extensive faulting, fracturing and hydrothermal activity during Late Miocene-Pliocene volcanism, which contributed to the development of kaolinite deposits under acidic environmental conditions. With regard to industrial applications, the low-Fe kaolinized schists are suitable for use in refractories and paper coatings, while the claystone is suitable for use in ceramics and in the white-cement industry.

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“…Ratios of elements that are relatively immobile during hydrothermal alteration can be used geochemically to constrain the origins of felsic volcanic rocks (see Jenner, 1996). These ratios include Zr/Y (Lesher et al, 1986;MacLean and Barrett, 1993), Th/Nb (Gorton and Schandl, 2000;Schandl and Gorton, 2002), and Zr/TiO 2 (Winchester and Floyd, 1977;Petersen, 1983;Lavery, 1985;MacLean and Barrett, 1993). Although the felsic volcanic rocks of the Nepisiguit Falls and Flat Landing Brook formations are quite similar in terms of bulk composition, Zr/ TiO 2 serves as a reliable chemostratigraphic discriminator (Lentz et al, 1997;Lentz, 1999b).…”

Section: Introductionmentioning

confidence: 96%

Chemostratigraphy at the Brunswick No. 6 Volcanic-Sediment-Hosted Massive Sulfide Deposit, New Brunswick: Resolving Geometry from Drill Core in Deformed Felsic Volcanic Rocks

Wills

Lentz

Roy³

2006

Exploration and Mining Geology

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Diamond-drill hole DDH-B357, located 1.5 km north of the Brunswick No. 6 Zn-PbCu-Ag volcanic-sediment-hosted massive sulfide (VSHMS) deposit, intersects three exhalative horizons within variably altered felsic volcanic rocks of the Nepisiguit Falls and Flat Landing Brook formations. These three petrographically indistinguishable iron formation intervals (Fe 2 O 3 T ≥ 21.4 wt.%) likely represent cogenetic hydrothermal sedimentary units because they display a common geochemical signature: Fe 2 O 3 T = 42.9 ± 10.5 wt.%, MnO = 5.4 ± 3.1 wt.%, elevated base metal values (Zn+Pb = 1999 ± 1091 ppm), strong enrichment in additional exhalative components (CaO = 5.3 ± 3.9 wt.%; P 2 O 5 = 1.43 ± 1.00 wt.%), oxidized signature (Fe/Mn = 10 ± 6), as well as a common immobile element signature (Zr/TiO 2 = 0.025 ± 0.007) representative of a pelagic source. The calc-alkaline to transitional host volcanic rocks can be discriminated by Zr/TiO 2 , and to a lesser extent by Th/Nb: Nepisiguit Falls Formation: Zr/TiO 2 = 0.053 ± 0.004, Th/Nb = 1.08 ± 0.37; Flat Landing Brook Formation: Zr/TiO 2 = 0.107 ± 0.043, Th/Nb = 0.86 ± 0.17. A symmetrical repetition of the footwall-iron formation-hanging wall stratigraphic sequence is observed in DDH-B357, with distinct felsic volcanic rock domains separated by the three iron formations. This is best explained by parasitic F 2 folds on the west flank of the south-plunging Brunswick antiform, similar to the fold closures known to host massive sulfide accumulations in the Brunswick No. 6 and No. 12 mines. Iron formation geochemistry and felsic volcanic rock chemostratigraphy from drill core sampling can provide an effective mineral exploration tool for the structurally complex rocks of the Bathurst Mining Camp.Sommaire -Le forage au diamant DDH-B357, situé à 1.5 km au nord du gisement de Sulfures Massifs à Encaissant Volcanique et Sédimentaire (SMEVS) de Zn-Pb-Cu-Ag Brunswick No. 6 recoupe trois horizons exhalatifs au sein des roches volcaniques felsiques diversement altérées des formations de Nepisiguit Falls et de Flat Landing Brook. Ces trois intervalles de formation de fer, impossibles à distinguer pétrographiquement les uns des autres, représentent vraisemblablement des unités sédimentaires hydrothermales cogénétiques sur la base de leur signature géochimique commune: Fe 2 O 3 T = 42.9 ± 10.5 % poids, MnO = 5.4 ± 3.1 % poids, des teneurs élevées en métaux usuels (Zn+Pb = 1999 ± 1091 ppm), un fort enrichissement en composantes exhalatives additionnelles (CaO = 5.3 ± 3.9 % poids; P 2 O 5 = 1.43 ± 1.00 % poids), une signature oxydée (Fe/ Mn = 10 ± 6), ainsi qu'une signature d'éléments immobiles communs (Zr/TiO 2 = 0.025 ± 0.007) indicative d'une source pélagique. Les roches volcaniques encaissantes calco-alcalines à transitionnelles peuvent êtres reconnues par leur rapport Zr/TiO 2 , et à un moindre degré par leur rapport Th/Nb: Formation de Nepisiguit Falls: Zr/TiO 2 = 0.053 ± 0.004, Th/Nb = 1.08 ± 0.37; Formation de Flat Landing Brook: Zr/TiO 2 = 0.107 ± 0.043, Th/Nb = 0.86 ± 0.17. Une répétiti...

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Quantifying chemical changes in hydrothermally altered volcanic sequences — silica enrichment as a guide to the crandon massive sulfide deposit, Wisconsin, U.S.A.

Cited by 16 publications

References 16 publications

Mineralogy, micromorphology, geochemistry and genesis of a hydrothermal kaolinite deposit and altered Miocene host volcanites in the Hallaçlar area, Uşak, western Turkey

Mineralogy, micromorphology, geochemistry and genesis of a hydrothermal kaolinite deposit and altered Miocene host volcanites in the Hallaçlar area, Uşak, western Turkey

Mineralogy, geochemistry and genesis of the Taşoluk kaolinite deposits in pre-Early Cambrian metamorphites and Neogene volcanites of Afyonkarahisar, Turkey

Chemostratigraphy at the Brunswick No. 6 Volcanic-Sediment-Hosted Massive Sulfide Deposit, New Brunswick: Resolving Geometry from Drill Core in Deformed Felsic Volcanic Rocks

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