scholarly journals Basaltic to andesitic volcaniclastic rocks in the Blake River Group, Abitibi Greenstone Belt: 1. Mode of emplacement in three areas1This article is a companion paper to Ross et al. 2011. Basaltic to andesitic volcaniclastic rocks in the Blake River Group, Abitibi Greenstone Belt: 2. Origin, geochemistry, and geochronology. Canadian Journal of Earth Sciences, 48: this issue.2MRNF Contribution BEGQ 8439-2010/2011-1. Natural Resources Canada, Earth Science Sector Contribution 20100253.

2011 ◽  
Vol 48 (4) ◽  
pp. 728-756 ◽  
Author(s):  
Pierre-Simon Ross ◽  
Jean Goutier ◽  
Patrick Mercier-Langevin ◽  
Benoît Dubé
Keyword(s):  
Greenstone Belt ◽  
Earth Science ◽  
Volcanic Rocks ◽  
Companion Paper ◽  
Density Currents ◽  
Abitibi Greenstone Belt ◽  
Volcaniclastic Rocks ◽  
Emplacement Processes ◽  
Felsic Volcanic ◽  
High Level

The Archean Blake River Group (BRG) of Ontario and Quebec is dominated by submarine mafic to intermediate lavas, with more restricted felsic volcanic rocks. Given the good quality of outcrop, and high level of preservation of some BRG rocks, the mafic to intermediate lavas were used in the 1970s and 1980s to better understand the evolution of massive and pillowed submarine flows, and their associated fragmental facies (pillow breccias, hyaloclastite). Potentially, the BRG could also represent a useful volcanic succession for the study of explosive submarine eruption products in the ancient record. Before this is possible, however, a regional inventory of the mafic to intermediate volcaniclastic units is needed to clarify their characteristics and origins. In this paper, we compare and contrast volcaniclastic rocks from three areas within the same formation of the northern BRG in Quebec: the Monsabrais area, the Lac Duparquet area, and the D’Alembert tuff area. Close examination reveals pronounced differences in terms of lateral continuity, thickness, grading, bedding, clast shapes, textures, etc. in the volcaniclastic rocks. These differences are interpreted to reflect vastly different emplacement processes, ranging from hyaloclastite generation as a result of self-fragmentation and lava contact with water (dominant in the Monsabrais and Lac Duparquet areas) to aqueous density currents likely fed directly by explosive submarine eruptions (dominant in the D’Alembert tuff).

Basaltic to andesitic volcaniclastic rocks in the Blake River Group, Abitibi Greenstone Belt: 2. Origin, geochemistry, and geochronology 1This article is a companion paper to Ross et al. 2011. Basaltic to andesitic volcaniclastic rocks in the Blake River Group, Abitibi Greenstone Belt: 1. Mode of emplacement in three areas. Canadian Journal of Earth Sciences, 48: this issue.2Ministère des Ressources naturelles et de la Faune (MRNF) Contribution BEGQ 8439-2010/2011-2. Natural Resources Canada, Earth Science Sector Contribution 20100252.

2011 ◽  
Vol 48 (4) ◽  
pp. 757-777 ◽  
Author(s):  
P.-S. Ross ◽  
V. McNicoll ◽  
J. Goutier ◽  
P. Mercier-Langevin ◽  
B. Dubé
Keyword(s):  
Greenstone Belt ◽  
Earth Science ◽  
Companion Paper ◽  
Physical Characteristics ◽  
Explosive Eruptions ◽  
Density Currents ◽  
Abitibi Greenstone Belt ◽  
Volcaniclastic Rocks ◽  
Trace Element Profiles

In the Archean Blake River Group, mafic to intermediate fragmental units have controversially been proposed to have formed during the collapse of a giant submarine caldera. This paper describes and interprets these rocks, summarizing their physical characteristics, inferred origins, age relationships, and geochemical signatures. The widespread Stadacona member, south of Rouyn-Noranda, consists of several hundred metres of bedded volcaniclastic rocks interpreted to have been mostly deposited from aqueous density currents fed directly by explosive eruptions. The magmas involved in these eruptions were plagioclase-phyric, tholeiitic to transitional basalts. The similarly widespread D’Alembert tuff, in the northern part of the Blake River Group, shares many physical characteristics with the Stadacona member and is thought to have a similar origin. However, the D’Alembert tuff is approximately six million years younger than the Stadacona member. It is composed mostly of transitional to calc-alkaline andesites and basaltic andesites with very distinct trace element profiles. Volcaniclastic rocks from other areas, such as Tannahill Township in Ontario and the Monsabrais area in Quebec, are interpreted to represent mostly in situ to remobilized hyaloclastite, with no explosive eruptions involved in their genesis. Our observations and interpretations are not compatible with models in which the volcaniclastic units are emplaced during a catastrophic event in relation with the collapse of a giant caldera. Instead, the fragmental rocks were produced by various mechanisms at many distinct times during the evolution of the Blake River Group.

The tectonic evolution of the Abitibi greenstone belt of Canada

1986 ◽  
Vol 123 (2) ◽  
pp. 153-166 ◽  
Author(s):  
John Ludden ◽  
Claude Hubert ◽  
Clement Gariépy
Keyword(s):  
Greenstone Belt ◽  
Volcanic Rocks ◽  
Taupo Volcanic Zone ◽  
Rift Basins ◽  
Volcanic Zone ◽  
Tectonic Model ◽  
Abitibi Greenstone Belt ◽  
Southern Volcanic Zone ◽  
The Difference ◽  
Felsic Volcanic

AbstractBased on structural, geochemical, sedimentological and geochronological studies, we have formulated a model for the evolution of the late Archaean Abitibi greenstone belt of the Superior Province of Canada. The southern volcanic zone (SVZ) of the belt is dominated by komatiitic to tholeiitic volcanic plateaux and large, bimodal, mafic-felsic volcanic centres. These volcanic rocks were erupted between approximately 2710 Ma and 2700 Ma in a series of rift basins formed as a result of wrench-fault tectonics.The SVZ superimposes an older volcanic terrane which is characterized in the northern volcanic zone (NVZ) of the Abitibi belt and is approximately 2720 Ma or older. The NVZ comprises basaltic to andesitic and dacitic subaqueous massive volcanics which are cored by comagmatic sill complexes and layered mafic-anorthositic plutonic complexes. These volcanics are overlain by felsic pyroclastic rocks that were comagmatic with the emplacement of tonalitic plutons at 2717 ±2 Ma.The tectonic model envisages the SVZ to have formed in a series of rift basins which dissected an earlier formed volcanic arc (the NVZ). Analogous rift environments have been postulated for the Hokuroko basin of Japan, the Taupo volcanic zone of New Zealand and the Sumatra and Nicaragua arcs. The difference between rift related ‘submergent’ volcanism in the SVZ and ‘emergent’ volcanism in the NVZ resulted in the contrasting metallogenic styles, the former being characterized by syngenetic massive sulphide deposits, whilst the latter was dominated by epigenetic ‘porphyry-type’ Cu(Au) deposits.

Geochemistry of the late Archean Banting Group, Yellowknife greenstone belt, Slave Province, Canada: simultaneous melting of the upper mantle and juvenile mafic crust

2002 ◽  
Vol 39 (11) ◽  
pp. 1635-1656 ◽  
Author(s):  
Brian Cousens ◽  
Kathy Facey ◽  
Hendrik Falck
Keyword(s):  
Upper Mantle ◽  
Greenstone Belt ◽  
Tectonic Setting ◽  
Volcanic Rocks ◽  
Heavy Rare Earth Element ◽  
Element Abundances ◽  
Slave Province ◽  
Volcaniclastic Rocks ◽  
Felsic Volcanic ◽  
Felsic Rocks

This study investigates the geochemistry and tectonic setting of the 2.66 Ga Banting Group, the younger sequence of volcanic rocks in the Yellowknife greenstone belt, and its relationship to older tholeiitic volcanic rocks of the 2.72–2.70 Ga Kam Group. The Banting Group includes a much higher proportion of felsic volcanic and volcaniclastic rocks than the Kam Group, but mafic to intermediate volcanic rocks are common. Banting basalts are tholeiitic and are melts of Archean depleted upper mantle, as are basalts of the Kam Group. In contrast, Banting dacites and rhyolites have much lower heavy rare earth element abundances and generally have higher initial 143Nd/144Nd than Kam felsic rocks. The chemistry of the felsic rocks provides a geochemical signature to distinguish rocks of Kam versus Banting age where complex structures have obscured the stratigraphy. Whereas Kam felsic rocks evolved from mafic parents by assimilation – fractional crystallization processes, Banting felsic rocks have compositions similar to Archean tonalite–trondhjemite–dacite suites, as well as modern adakites, and appear to be melts of juvenile, garnet-bearing, hydrated mafic crust, possibly underplated Kam basalts. The nearby 2.66 Ga felsic complex at Clan Lake mimics the geochemical systematics of the Banting Group, and thus Banting-like rocks may reflect a regional crustal melting event at this time.

Tholeiitic volcanic rocks of the late Archean Blake River Group, southern Abitibi greenstone belt: origin and geodynamic implications

1992 ◽  
Vol 29 (7) ◽  
pp. 1448-1458 ◽  
Author(s):  
M. R. Laflèche ◽  
C. Dupuy ◽  
J. Dostal
Keyword(s):  
Greenstone Belt ◽  
Volcanic Rocks ◽  
Incompatible Trace Element ◽  
Progressive Change ◽  
Abitibi Greenstone Belt ◽  
Mid Ocean Ridge ◽  
Compositional Variations ◽  
Arc Setting ◽  
Back Arc ◽  
Ocean Ridge

The late Archean Blake River Group volcanic sequence forms the uppermost part of the southern Abitibi greenstone belt in Quebec. The group is mainly composed of mid-ocean-ridge basalt (MORB)-like tholeiites that show a progressive change of several incompatible trace element ratios (e.g., Nb/Th, Nb/Ta, La/Yb, and Zr/Y) during differentiation. The compositional variations are inferred to be the result of fractional crystallization coupled with mixing–contamination of tholeiites by calc-alkaline magma which produced the mafic–intermediate lavas intercalated with the tholeiites in the uppermost part of the sequence. The MORB-like tholeiites were probably emplaced in a back-arc setting.

Volcanic rocks of the Blake River Group, Abitibi Greenstone Belt, Ontario, and their sulfur content

1977 ◽  
Vol 14 (4) ◽  
pp. 539-550 ◽  
Author(s):  
A. J. Naldrett ◽  
A. M. Goodwin
Keyword(s):  
Sulfur Content ◽  
Greenstone Belt ◽  
Geometric Mean ◽  
Volcanic Rocks ◽  
Smooth Curve ◽  
Arithmetic Mean ◽  
Arithmetic Means ◽  
Basaltic Rocks ◽  
Abitibi Greenstone Belt ◽  
Stratigraphic Height

Six hundred and ninety samples of volcanic rocks from the Blake River Group of the Abitibi Greenstone Belt have analysed for sulfur on a Leco sulfur analyser. Basaltic rocks have been subdivided into komatiites, Fe-rich tholeiites, Al-rich basalts, and intermediate basalts with more than 1% TiO2 and with less than 1% TiO2. Andesites have been subdivided into Fe-rich types, Al-rich types, and others. All dacites are grouped together as are all rhyolites. Rocks of many of these subdivisions occur at more than one level within the Blake River stratigraphy. Within a given rock subdivision, the sulfur content is distributed log normally. When the geometric mean of the sulfur content of each of the subdivisions outlined above is plotted against the arithmetic mean of the FeO content, a smooth curve is obtained, with sulfur increasing markedly with increase in FeO. The data give no indication of any change in sulfur content of a given rock subdivision with stratigraphic height. The arithmetic mean of the sulfur content of each rock subdivision also increases with the mean FeO content, although less smoothly than the geometric mean. The arithmetic means of sulfur content fall within the scatter of points obtained experimentally for the sulfur content of sulfur saturated basalts, supporting the contention that the Blake River rocks may have been saturated with sulfur at the time of their extrusion.

scholarly journals Detailed mapping and lithogeochemistry of Neoarchean volcanic rocks: Beaulieu volcanic belt, Slave Craton, NWT

2020 ◽  
Vol 6 (1) ◽  
Author(s):  
Shelby Brandon Austin-Fafard ◽  
Michelle DeWolfe ◽  
Camille Partin ◽  
Bernadette Knox
Keyword(s):  
Volcanic Rocks ◽  
Volcanic Belt ◽  
Massive Sulfide ◽  
Lake Area ◽  
Density Currents ◽  
Volcanogenic Massive Sulfide ◽  
The South ◽  
Slave Craton ◽  
Volcaniclastic Rocks ◽  
Tuff Breccia

Neoarchean volcanic rocks of the Beaulieu River volcanic belt structurally overlie basement rocks of the Sleepy Dragon Complex (ca. 2.85 Ga), approximately 100 km east northeast of Yellowknife. The volcanic belt is comprised of complex lithofacies, including basalt, andesite, rhyolite, and associated volcaniclastic rocks, and hosts the Sunrise volcanogenic massive sulfide deposit. The absolute age of the volcanic strata is not known, nor is the stratigraphy well-defined; therefore, the Beaulieu River volcanic belt cannot be easily correlated to other greenstone belts within the Slave craton. The main objective of this study is to document the litho- and chemo-stratigraphy of the volcanic rocks, and particularly the rhyolite dome, located at the south end  of Sunset Lake to reconstruct their volcanic and petrogenetic evolution, and determine their relationship to the volcanic strata that hosts the Sunrise VMS deposit, located ~6km to the north of the study area. Detailed mapping (1:2000) was completed over two field seasons (2018 and 2019) and shows that the volcanic rocks in the south Sunset Lake area comprise a complex stratigraphy consisting of basaltic, andesitic and rhyolitic lithofacies. This includes massive to pillow basalt and andesite, with lesser amounts of massive to in-situ brecciated, weakly quartz-plagioclase porphyritic rhyolite, heterolithic tuff to lapilli- tuff and felsic tuff to tuff breccia. The felsic clasts within the felsic volcaniclastic rocks are similar in composition to the coherent rhyolite. Units have a trace element geochemical signatures that vary from tholeiitic to calc-alkaline, arc-like rocks. Volumetrically, the volcanic strata in the south Sunset Lake area has a significant amount of volcaniclastic rocks, ranging from tuff to tuff breccia units. The volcaniclastic rocks are interpreted to have been deposited by a series of debris flows and eruption-fed density currents. The stratigraphy of the volcanic rocks in south Sunset Lake is very similar to that of the stratigraphy that hosts the Sunrise VMS deposit. Evidence of a vent proximal environment (e.g. rhyolite dome, peperite, syn-volcanic intrusions) and porous, volcanic debris accumulating on the seafloor highlight conditions favourable for volcanogenic massive sulfide-type mineralization in the south Sunset Lake area.

The Pontiac problem, Quebec–Ontario, in the light of gravity data

1987 ◽  
Vol 24 (9) ◽  
pp. 1916-1919 ◽  
Author(s):  
J. Kalliokoski
Keyword(s):  
Gravity Anomaly ◽  
Greenstone Belt ◽  
Gravity Data ◽  
Volcanic Rocks ◽  
Sedimentary Rocks ◽  
Iron Formation ◽  
Bouguer Gravity ◽  
The West ◽  
Abitibi Greenstone Belt ◽  
Uplifted Block

A belt of Archean quartzose metasedimentary gneisses with minor mafic volcanic rocks (the Pontiac Group) lies south of the Blake River and older Archean mafic volcanic rocks of the Abitibi Greenstone Belt, and is separated from them by the Larder Lake – Cadillac Break. To the west of the Pontiac Group, on strike, is the Archean Larder Lake Group of turbidite conglomerate, argillite, limestone, and iron formation with abundant mafic flows and intrusions. These strata also lie south of the Larder Lake – Cadillac Break and south of the Blake River and older Archean mafic volcanic rocks. The western contact between the Pontiac and Larder Lake groups is covered by a narrow north–south strip of Proterozoic Cobalt sedimentary rocks. On the basis of gravity work that compares the Bouguer gravity anomaly gradient across the Cadillac Break with that across the west margin of the Pontiac Group, it is proposed that the Larder Lake and Pontiac groups are separated by a north–south fault and that the Pontiac Group represents a lithologically distinct uplifted block. The Pontiac block may be an Archean terrane.

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