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

2017 ◽  
Vol 54 (6) ◽  
pp. 622-638 ◽  
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.

Progressive metamorphism of pelitic and quartzofeldspathic rocks in the Grenville Province of western Labrador — tectonic implications of bathozone 6 assemblages

1983 ◽  
Vol 20 (12) ◽  
pp. 1791-1804 ◽  
Author(s):  
T. Rivers
Keyword(s):  
Experimental Data ◽  
Pressure Gradient ◽  
Granulite Facies ◽  
Lithostatic Pressure ◽  
Lower Grade ◽  
High Grade ◽  
Tectonic Zone ◽  
Grenville Province ◽  
Mineral Assemblages ◽  
Grenvillian Orogeny

Aphebian metapelites and quartzofeldspathic rocks from the Grenville Province south of the Labrador Trough display progressive changes in mineral assemblages as a result of Grenvillian metamorphism, consistent with variation in grade from greenschist to upper amphibolite facies. The following metamorphic zones have been delineated: (i) chlorite–muscovite; (ii) chlorite–muscovite–biotite; (iii) chlorite–muscovite–biotite–garnet; (iv) muscovite–staurolite–kyanite; (v) muscovite–garnet–biotite–kyanite; (vi) muscovite–garnet–biotite–kyanite–granitic veins; (vii) K–feldspar–kyanite – granitic veins; (viii) K-feldspar–sillimanite–granitic veins. Reactions linking the lower grade metamorphic zones are interpreted to be dehydration phenomena, whilst anatectic reactions occur at higher grades. At lower metamorphic grades aH2O was high [Formula: see text] but it declined progressively as water entered the melt phase during higher grade anatectic reactions. With the onset of vapour-absent anatexis, the restite assemblage became essentially "dry" [Formula: see text], and biotite breakdown occurred in granulite-facies rocks east of the study area. Consideration of available experimental data suggests that metamorphic temperatures ranged from approximately 450 to 750 °C across the study area. Lithostatic pressure during metamorphism reached about 8 kbar (800 MPa) in the high-grade zones, with estimates at lower grades being poorly constrained; however, a steep pressure gradient across the map area is postulated.This is the first reported occurrence of bathozone 6 assemblages from a progressive metamorphic sequence, and it indicates the presence of an unusually great thickness of supracrustal rocks during the Grenvillian Orogeny. This was achieved by imbricate stacking of thrust slices, perhaps doubling the thickness of the crust in the Grenville Front Tectonic Zone, creating a huge gravity anomaly of which a remnant still persists today.

scholarly journals NEW FIND OF ZUNYITE IN ADVANCED ARGILLIC ALTERATION OF RHYOLITES, KOS ISLAND, SOUTH AEGEAN VOLCANIC ARC , GREECE

2004 ◽  
Vol 36 (1) ◽  
pp. 474 ◽  
Author(s):  
D. Papoulis ◽  
P. Tsolis-Katagas ◽  
C. Katagas
Keyword(s):  
Raman Spectroscopy ◽  
Hydrothermal Alteration ◽  
Volcanic Rocks ◽  
Hydrothermal Fluids ◽  
Accessory Mineral ◽  
Volcanic Arc ◽  
Argillic Alteration ◽  
Edx Analyses ◽  
Advanced Argillic Alteration

Zunyite [Ali3SÌ5C>2o(OH,F)i8CI], an extremely rare mineral, was found as an accessory mineral in highly altered rhyolitic rocks at Kefalos, southwestern Kos, and in a completely kaolinized rhyolitic dyke at Asfendiou, northeastern Kos. It is associated with dickite, kaolinite, quartz and minor pyrophyllite. Kos Island contains both Tertiary and Quaternary volcanic rocks. Zunyite has been identified by XRD and studied by SEM, EDS, Raman spectroscopy and FTIR spectroscopy. The presence of zunyite, in the highly altered samples is significant for the determination of the conditions of the hydrothermal alteration that took place. Zunyite crystals, are up to 90 pm in diameter but usually are less than 10 pm; the crystals are partly covered by kaolinite layers. EDX analyses on the surface of zunyite revealed AI2O3/S1O2 values raging from 2.6 to 2.7. The occurrence of zunyite suggests incorporation of hydrothermal fluids rich in F" and CI", thus indicating contamination by seawater

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

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.

Pinwarian (1.50 Ga) volcanism and hydrothermal activity at the eastern margin of the Wakeham Group, Grenville Province, Quebec

2005 ◽  
Vol 42 (10) ◽  
pp. 1749-1782 ◽  
Author(s):  
Louise Corriveau ◽  
Anne-Laure Bonnet
Keyword(s):  
Granulite Facies ◽  
Hydrothermal Activity ◽  
Grenville Province ◽  
Magmatic Arc ◽  
Argillic Alteration ◽  
Supracrustal Belt ◽  
Hydrothermal Alteration Zones ◽  
Continental Magmatic Arc ◽  
Arc Volcano ◽  
Volcanic Belts

Volcanic belts developed along the southeastern continental margin of Laurentia between 1.70 and 1.30 Ga and subsequently metamorphosed at high grade are today largely concealed among gneiss complexes of the Grenville Province. At the eastern end of the Wakeham Group and in the La Romaine Supracrustal Belt to the east, four 1.50 Ga volcanic centres were found among gneissic synvolcanic intrusions typical of the 1.52–1.46 Ga Pinwarian continental magmatic arc. Upper amphibolite- to granulite-facies rhyolitic to dacitic lavas and coarse lapillistone overlie or are intimately associated with arenites typical of the Wakeham Group. Garnetite, ironstone, carbonate rock, calc-silicate rock, and sillimanite-bearing nodules, veins, and gneiss, locally preserving lapilli, are also present. The distribution, paragenesis, and modes of most of these latter units differ from those of normal metasediments but are diagnostic of metamorphosed exhalites and hydrothermal alteration zones. In the La Romaine Supracrustal Belt, they are associated with pyroclastic horizons and a mineralized composite amphibolite unit. Volcanic textures include flow banding, wispy lapilli moulding fragmented lapilli and rounded lapilli with quartz-feldspar mosaics (filled vesicles), and in situ shattering of lapilli. These textures and the presence of advanced argillic alteration point to vesicular volcanism and hydrothermal activity in a subaerial to shallow submarine environment. Rare mafic lapilli attest to coeval mafic magmatism. The pervasive calc-alkaline signature of the eruptive and intrusive felsic to mafic rocks and their distribution are compatible with the development of 1.50 Ga intra-arc volcano-sedimentary belts stemming from the Wakeham Group basin and extending eastward within the Pinwarian continental magmatic arc.

Proterozoic metamorphism in the Grenville Province: a study in the Double Mer – Lake Melville area, eastern Labrador

1988 ◽  
Vol 25 (11) ◽  
pp. 1895-1905 ◽  
Author(s):  
C. F. Gower ◽  
P. Erdmer
Keyword(s):  
Granulite Facies ◽  
High Grade ◽  
Structural Configuration ◽  
Geochronological Data ◽  
Granitic Gneiss ◽  
Grenville Province ◽  
Accessory Minerals ◽  
Mineral Assemblages ◽  
Host Rocks ◽  
Metamorphic Gradient

A regional metamorphic gradient from upper greenschist to granulite facies is identified south of the Grenville front in the Double Mer – Lake Melville area of eastern Labrador. Mineral assemblages in politic–granitic gneiss, amphibole-bearing quartzo-feldspathic gneiss, and coronitic metagabbro allow three major metamorphic domains to be established. These are collectively divisible into 11 subdomains. Geothermobarometry applied to the higher grade domains suggests that each is characterized by specific P–T conditions, which achieved 1000–1100 MPa and 700–800 °C in the deepest level rocks.The problem of reconciling geochronological data (which record a major orogenic event at 1650 Ma) with the occurrence of high-grade mineral assemblages in 1426 Ma metagabbro (which suggests a pervasive Grenvillian event) is discussed in terms of three models. The preferred model envisages crustal stabilization at 1650–1600 Ma to give high-grade mineral assemblages seen in the host rocks and with which mineral assemblages in coronitic metagabbro equilibrated after their emplacement at 1426 Ma. During Grenvillian orogenesis (1080–920 Ma) the present structural configuration was achieved by thrust stacking. This imparted a sporadic metamorphic and structural overprint and Grenvillian ages in selected accessory minerals.

Polymetamorphism of marbles in the Morin terrane, Grenville Province, Quebec

2005 ◽  
Vol 42 (10) ◽  
pp. 1949-1965 ◽  
Author(s):  
William H Peck ◽  
Michael T DeAngelis ◽  
Michael T Meredith ◽  
Etienne Morin
Keyword(s):  
Shear Zones ◽  
Granulite Facies ◽  
Grenville Province ◽  
Anorthosite Massif ◽  
Mineral Assemblages ◽  
Intrusive Rocks ◽  
Granitic Intrusions ◽  
T Path ◽  
The Village

The Morin terrane (Grenville Province, Quebec) is dominated by the 1.15 Ga Morin Anorthosite Massif and related granitic intrusions, all of which exhibit granulite-facies mineral assemblages. Anorthosite-suite rocks are deformed both in shear zones and in the interior of the terrane and show intrusive contact relations with marble along road cuts near the village of St. Jovite. Intrusive rocks exposed in these road cuts have well-developed skarns, which were deformed with the intrusions after emplacement. Skarn minerals are consumed by garnet-forming reactions (e.g., An + Wo = Gr + Qtz) that preserve granulite-facies temperatures and pressures. Calcite–graphite thermometry of Morin terrane marbles records temperatures of 755 ± 38 °C (n = 21), independent of proximity to anorthosite-suite plutons. Preserved metamorphic conditions and the retrograde pressure–temperature (P–T) path in the Morin terrane are very similar to conditions during the 1.07 Ga Ottawan orogeny in the Adirondack Highlands. Metamorphism and deformation of anorthosite-suite rocks and marbles of the Morin terrane are consistent with anorthosite intrusion followed by a distinct granulite-facies overprint.

Kaolinization of the Kimolos Island volcanics, Cyclades, Greece

Clay Minerals ◽  
1989 ◽  
Vol 24 (1) ◽  
pp. 75-89 ◽  
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.

scholarly journals Comparison of Different Algorithms to Map Hydrothermal Alteration Zones Using ASTER Remote Sensing Data for Polymetallic Vein-Type Ore Exploration: Toroud–Chahshirin Magmatic Belt (TCMB), North Iran

2019 ◽  
Vol 11 (5) ◽  
pp. 495 ◽  
Author(s):  
Lida Noori ◽  
Amin Pour ◽  
Ghasem Askari ◽  
Nader Taghipour ◽  
Biswajeet Pradhan ◽  
...  
Keyword(s):  
Remote Sensing ◽  
Hydrothermal Alteration ◽  
Remote Sensing Data ◽  
Base Metals ◽  
Argillic Alteration ◽  
Mineral Assemblages ◽  
Vein Type ◽  
North Of Iran ◽  
Advanced Argillic Alteration ◽  
Hydrothermal Alteration Zones

Polymetallic vein-type ores are important sources of precious metal and a principal type of orebody for various base-metals. In this research, Advanced Spaceborne Thermal Emission and Reflection Radiometer (ASTER) remote sensing data were used for mapping hydrothermal alteration zones associated with epithermal polymetallic vein-type mineralization in the Toroud–Chahshirin Magmatic Belt (TCMB), North of Iran. The TCMB is the largest known goldfield and base metals province in the central-north of Iran. Propylitic, phyllic, argillic, and advanced argillic alteration and silicification zones are typically associated with Au-Cu, Ag, and/or Pb-Zn mineralization in the TCMB. Specialized image processing techniques, namely Selective Principal Component Analysis (SPCA), Band Ratio Matrix Transformation (BRMT), Spectral Angle Mapper (SAM) and Mixture Tuned Matched Filtering (MTMF) were implemented and compared to map hydrothermal alteration minerals at the pixel and sub-pixel levels. Subtle differences between altered and non-altered rocks and hydrothermal alteration mineral assemblages were detected and mapped in the study area. The SPCA and BRMT spectral transformation algorithms discriminated the propylitic, phyllic, argillic and advanced argillic alteration and silicification zones as well as lithological units. The SAM and MTMF spectral mapping algorithms detected spectrally dominated mineral groups such as muscovite/montmorillonite/illite, hematite/jarosite, and chlorite/epidote/calcite mineral assemblages, systematically. Comprehensive fieldwork and laboratory analysis, including X-ray diffraction (XRD), petrographic study, and spectroscopy were conducted in the study area for verifying the remote sensing outputs. Results indicate several high potential zones of epithermal polymetallic vein-type mineralization in the northeastern and southwestern parts of the study area, which can be considered for future systematic exploration programs. The approach used in this research has great implications for the exploration of epithermal polymetallic vein-type mineralization in other base metals provinces in Iran and semi-arid regions around the world.

Zonal structure of the Perth Road monzonite, Grenville Province, Ontario

1970 ◽  
Vol 7 (2) ◽  
pp. 414-434 ◽  
Author(s):  
I. F. Ermanovics
Keyword(s):  
Rock Type ◽  
Maximum Velocity ◽  
Alkali Feldspar ◽  
Granulite Facies ◽  
The Body ◽  
Grenville Province ◽  
Flow Models ◽  
Metasedimentary Rocks ◽  
Rock Types ◽  
Quartz Monzonite

The Perth Road pluton is a lenticular, grossly conformable body emplaced in metasedimentary rocks of the Grenville series during a period in which the enclosing gneisses deformed by plastic flow. The body is zoned and from the center outward comprises gabbro, diorite, monzonite (the dominant rock-type), quartz monzonite, and granite. The change from one rock-type to the next is gradual and the progressive acidification toward all the contacts, without regard to the type of enclosing gneiss, is taken as an indication of cogenesis of the plutonic assemblage; modal mineral variations of quartz, alkali-feldspar, plagioclase, and color index demonstrate this mineral progression.The enclosing crystalline metasedimentary rocks have been metamorphosed to the hornblende granulite facies, and although recrystallization has kept pace with deformation some cataclasis pervades all rocks. The pluton occupies a flattened crestal position of a doubly plunging fold, and all folds show a combination of fold-styles depending on the relative competence of the various rock-types. Flow models demonstrate that the early magmatic precipitates collected in regions of maximum velocity of the magma during folding of the enclosing envelope of gneisses and that syntectonic differentiation in this manner obtains for the Perth Road and other plutons in the area.

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