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.

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).

Tectonic and thermal history of the Anialik River area, northwestern Slave Province, Canada

1999 ◽  
Vol 36 (7) ◽  
pp. 1207-1226 ◽  
Author(s):  
C Relf ◽  
H A Sandeman ◽  
M E Villeneuve
Keyword(s):  
Shear Zone ◽  
Continental Crust ◽  
Greenstone Belt ◽  
Volcanic Rocks ◽  
Crustal Thickening ◽  
South Central ◽  
Slave Province ◽  
History Of ◽  
Arc Setting ◽  
Felsic Volcanic

The Anialik River area in the northwestern Slave Province comprises two geological domains of different age and origin that were tectonically juxtaposed at ca. 2650 Ma. The older domain, the Kangguyak gneiss belt, comprises ca. 3300-2700 Ma orthogneisses and paragneisses, interpreted as the remnants of a Mesoarchean continental margin. The younger domain, the Anialik River greenstone belt, consists of ca. 2680 Ma mafic to felsic volcanic rocks interpreted to have formed in an ensimatic island-arc setting. Structural and geochronological evidence suggest collision of the two domains began around 2650 Ma in a transpressive regime that involved oblique (sinistral) subduction of the greenstone belt beneath the Kangguyak domain along the Tokhokatak shear zone. Displacement continued until at least ca. 2600 Ma, when late, two-mica granites intruded along and were deformed in the shear zone. Following ca. 2600 Ma, rocks in both domains and along the fault cooled rapidly to about 350°C. Strongly overprinted muscovite spectra and the young ages for biotite throughout the region imply that a thermal event reset all biotites (but not muscovite) at ca. 2000-1900 Ma, possibly associated with crustal thickening associated with Wopmay (Calderian) orogenesis. The tectonic history of the Anialik River area is significantly different from that documented in the south-central part of the Slave Province, suggesting the Kangguyak domain is a distinct fragment of continental crust that accreted independently from continental crust in the southern Slave Province.

Geochemistry and U/Pb geochronology of the Williams Brook area, Tobique-Chaleur zone, New Brunswick: stratigraphic and geotectonic setting of gold mineralization

2021 ◽  
Author(s):  
Dennis Sánchez-Mora ◽  
Christopher R.M. McFarlane ◽  
James A Walker ◽  
David R. Lentz
Keyword(s):  
New Brunswick ◽  
Gold Mineralization ◽  
Tectonic Setting ◽  
Volcanic Rocks ◽  
Crustal Contamination ◽  
Volcanic Belt ◽  
Temporal Variations ◽  
Lower Percentage ◽  
Oblique Convergence ◽  
Felsic Volcanic

Gold mineralization at Williams Brook in northern New Brunswick is hosted within the Siluro-Devonian, bimodal, volcano-sedimentary rocks of the Tobique-Chaleur Zone (Wapske Formation). Gold mineralization occurs in two styles: 1) as disseminations (refractory gold) in rhyolite, and 2) in cross-cutting quartz veins (free gold). Dating of the felsic volcanic host rocks by in situ LA-ICP-MS zircon U-Pb geochronology returned ages of 422 ± 3, 409 ± 2, 408 ± 3, 405 ± 2, 401 ± 9 Ma. Zr/Y of subvolcanic felsic intrusion (<8 for syn-mineralization and >8 for post-mineralization) suggests evolution from transitional to more alkalic affinities. Two mineralizing events are recognized; the first is a disseminated mineralization style formed at ~422–416 Ma and the second consists of quartz vein-hosted gold emplaced at 410–408 Ma. Felsic rocks from Williams Brook and elsewhere in the Tobique Group (i.e. Wapske, Costigan Mountain, and Benjamin formations), and the Coastal Volcanic Belt have similar Th/Nb ratios of ~0.1 to 1, reflecting similar levels of crustal contamination, and similar Nb and Y content, suggesting A-type affinities. These data indicate a similar environment of formation. Regionally, mafic rocks show similar within-plate continental signatures and an E-MORB mantle source that formed from partial melts of 10–30%. Mafic volcanic rocks from Williams Brook have a more alkaline affinity (based on Ti/V), and derivation from lower percentage partial melting (~5%). The chemical and temporal variations in the Williams Brook rocks suggest that they were erupted in an evolving transpressional tectonic setting during the oblique convergence of Gondwana and Laurentia.

Chapter 3 Archean (>2.6 Ga) and Paleoproterozoic (2.5–1.8 Ga), pre- and syn-orogenic magmatism, sedimentation and mineralization in the Norrbotten and Överkalix lithotectonic units, Svecokarelian orogen

2020 ◽  
Vol 50 (1) ◽  
pp. 27-81 ◽  
Author(s):  
Stefan Bergman ◽  
Pär Weihed
Keyword(s):  
Variable Temperature ◽  
Tectonic Setting ◽  
Active Continental Margin ◽  
Volcanic Rocks ◽  
Shear Zones ◽  
Ductile Deformation ◽  
Fe Oxide ◽  
Ductile Shear Zones ◽  
Three Stages ◽  
Felsic Volcanic

AbstractTwo lithotectonic units (the Norrbotten and Överkalix units) occur inside the Paleoproterozoic (2.0–1.8 Ga) Svecokarelian orogen in northernmost Sweden. Archean (2.8–2.6 Ga and possibly older) basement, affected by a relict Neoarchean tectonometamorphic event, and early Paleoproterozoic (2.5–2.0 Ga) cover rocks constitute the pre-orogenic components in the orogen that are unique in Sweden. Siliciclastic sedimentary rocks, predominantly felsic volcanic rocks, and both spatially and temporally linked intrusive rock suites, deposited and emplaced at 1.9–1.8 Ga, form the syn-orogenic component. These magmatic suites evolved from magnesian and calc-alkaline to alkali–calcic compositions to ferroan and alkali–calcic varieties in a subduction-related tectonic setting. Apatite–Fe oxide, including the world's two largest underground Fe ore mines (Kiruna and Malmberget), skarn-related Fe oxide, base metal sulphide, and epigenetic Cu–Au and Au deposits occur in the Norrbotten lithotectonic unit. Low- to medium-pressure and variable temperature metamorphic conditions and polyphase Svecokarelian ductile deformation prevailed. The general northwesterly or north-northeasterly structural grain is controlled by ductile shear zones. The Paleotectonic evolution after the Neoarchean involved three stages: (1) intracratonic rifting prior to 2.0 Ga; (2) tectonic juxtaposition of the lithotectonic units during crustal shortening prior to 1.89 Ga; and (3) accretionary tectonic evolution along an active continental margin at 1.9–1.8 Ga.

Petrogenesis of the ca. 820–810 Ma felsic volcanic rocks in the Bikou Group: Implications for the tectonic setting of the western margin of the Yangtze Block

2019 ◽  
Vol 331 ◽  
pp. 105370 ◽  
Author(s):  
Tao Wu ◽  
Xuan–Ce Wang ◽  
Wu–Xian Li ◽  
Simon A. Wilde ◽  
Liyan Tian
Keyword(s):  
Tectonic Setting ◽  
Volcanic Rocks ◽  
Yangtze Block ◽  
Western Margin ◽  
Felsic Volcanic ◽  
Felsic Volcanic Rocks

Tectonic setting of late Archean bimodal volcanism in the Michipicoten (Wawa) greenstone belt, Ontario

1987 ◽  
Vol 24 (6) ◽  
pp. 1120-1134 ◽  
Author(s):  
Paul J. Sylvester ◽  
Kodjo Attoh ◽  
Klaus J. Schulz
Keyword(s):  
Greenstone Belt ◽  
Tectonic Setting ◽  
Volcanic Rocks ◽  
Depositional Environments ◽  
Oceanic Island ◽  
Island Arc ◽  
Basaltic Rocks ◽  
Bimodal Volcanism ◽  
Continental Arc ◽  
Convergent Plate Margin

The tectono-stratigraphic relationships, depositional environments, rock associations, and major- and trace-element compositions of the late Archean (2744–2696 Ma) bimodal basalt–rhyolite volcanic rocks of the Michipicoten (Wawa) greenstone belt, Ontario, are compatible with an origin along a convergent plate margin that varied laterally from an immature island arc built on oceanic crust to a more mature arc underlain by continental crust. This environment is similar to that of the Cenozoic Taupo–Kermadec–Tonga volcanic zone. Michipicoten basaltic rocks, most of which are proximal deposits compositionally similar ([La/Yb]n = 0.63–1.18) to modern oceanic island-arc tholeiites, are interpreted as having formed along the largely submerged island arc. Voluminous Michipicoten rhyolitic pyroclastic rocks ([La/Yb]n = 4.3–18.7, Ybn = 5.7–15.9) probably erupted subaerially from the continental arc, with distal facies deposited subaqueously on the adjacent oceanic island arc and proximal facies deposited in subaerial and shallow subaqueous environments on, or along the flanks of, the continental arc. The compositional similarity between the lower (2744 Ma) and upper (2696 Ma) volcanic sequences of the belt suggests that this island- and continental-arc configuration existed for at least 45 Ma. The Michipicoten belt may be a remnant of a larger, laterally heterogeneous volcanic terrane that also included the Abitibi greenstone belt.

An early Proterozoic volcanic arc succession in southeastern Wyoming

1984 ◽  
Vol 21 (4) ◽  
pp. 415-427 ◽  
Author(s):  
Kent C. Condie ◽  
Craig A. Shadel
Keyword(s):  
Fractional Crystallization ◽  
Tectonic Setting ◽  
Volcanic Rocks ◽  
Geochemical Data ◽  
Alkaline Basalt ◽  
Calc Alkaline ◽  
Early Proterozoic ◽  
Enriched Mantle ◽  
Sierra Madre ◽  
Felsic Volcanic

The Green Mountain Formation of early Proterozoic age in the Sierra Madre Range of southeastern Wyoming comprises a bimodal mafic and felsic volcanic assemblage. The rocks, which are chiefly breccias, agglomerates, flows, and volcaniclastic sediments, represent both subaerial and submarine eruptions and in part were redeposited in fluvial and nearshore marine environments. Volcanic rocks are clearly calc-alkaline in character and share a large number of geochemical features in common with continental-margin arcs or evolved oceanic-arc systems.The low Mg numbers and Ni contents of the basalts require 30–40% olivine fractional crystallization, and the high contents of the most incompatible elements, high (La/Sm)N ratios, and low Zr/Nb ratios require an undepleted or enriched mantle source. Geochemical data are consistent with an origin for the felsic volcanics and associated Encampment River granodiorite by shallow fractional crystallization of calc-alkaline basalt in a tectonic setting similar to modern arc systems. The near absence of andesites may reflect the retention of andesitic magma in crustal reservoirs during fractional cyrstallization.

Progressive accretion recorded in sedimentary rocks of the 3.28−3.23 Ga Fig Tree Group, Barberton Greenstone Belt

2021 ◽  
Author(s):  
Nadja Drabon ◽  
Donald R. Lowe
Keyword(s):  
Greenstone Belt ◽  
Tectonic Setting ◽  
Sedimentary Rocks ◽  
Foreland Basin ◽  
Barberton Greenstone Belt ◽  
The North ◽  
Tectonic Processes ◽  
Fig Tree ◽  
Felsic Volcanic ◽  
Tree Group

One of the major challenges in early Earth geology is the interpretation of the nature of the crust and tectonic processes due to the limited exposures of Archean rocks. This question is predominantly addressed by numerical modeling, structural geology, geochemical analyses, and petrological approaches. Here we report on the reconstruction of one of the oldest, well-preserved volcano-sedimentary sequences on Earth, the 3.28−3.22 Ga Fig Tree Group in the Barberton Greenstone Belt, South Africa, based on geochronology, provenance, and stratigraphy to provide new constraints on the nature of tectonic processes in the Archean. The Fig Tree basin was asymmetric and the onset of deposition varied across the greenstone belt. The Fig Tree Group is now preserved in east-west oriented bands of fault-bounded structural belts with those preserved in the southern parts of the greenstone belt showing an onset of deposition at 3.28 Ga, those in the center at 3.26 Ga, and those in the north at 3.24 Ga. Stratigraphically, the rocks display a general up-section trend from deeper to shallower-water deposition and/or from finer- to coarser-grained sedimentary rocks. Associated with this up-section stratigraphic trend, the sedimentary rocks show a change in provenance from more regionally similar to more locally variable, and an increase in felsic volcanic activity, especially toward the closure of Fig Tree deposition. The data is consistent with formation of the Fig Tree Group in a compressional tectonic setting by deposition in a foreland basin that experienced progressive accretion of crustal terranes onto a northward prograding fold-and-thrust belt.

Chronology of crustal growth and recycling in the Paleoproterozoic Amisk collage (Flin Flon Belt), Trans-Hudson Orogen, Canada

1999 ◽  
Vol 36 (11) ◽  
pp. 1807-1827 ◽  
Author(s):  
R A Stern ◽  
N Machado ◽  
E C Syme ◽  
S B Lucas ◽  
J David
Keyword(s):  
Upper Mantle ◽  
Tectonic Setting ◽  
Bulk Composition ◽  
Volcanic Rocks ◽  
Crust And Upper Mantle ◽  
Zircon Age ◽  
Magmatic Rocks ◽  
Main Period ◽  
Flin Flon ◽  
Back Arc

U-Pb zircon ages have been compiled for magmatic and sedimentary rocks from the low metamorphic grade portion of the Flin Flon greenstone belt, now recognized as a Paleoproterozoic tectonic collage. The "Amisk collage" formed in two major magmatic periods that were separated by an interval of intraoceanic accretionary tectonics. Pre-accretionary volcanic and plutonic rocks of arc and ocean-floor tectonic affinities have crystallization ages of 1.906-1.901 and 1.888-1.881 Ga; the earlier period was dominated by juvenile tholeiitic arc basalts and related back-arc-basin basalts, and the younger period by juvenile calc-alkaline volcanic rocks and turbidites. Intraoceanic accretion of the diverse tectono-stratigraphic assemblages may have commenced between 1.90 and 1.89 Ga, but the main period was 1.88-1.87 Ga. The post-accretionary period (1.876-1.838 Ga) was characterized by intrusion of juvenile calk-alkaline plutons generated by a successor arc that stitched the diverse pre-accretionary assemblages. Marine to subaerial volcaniclastic and epiclastic units were deposited in successor basins <=1.87 Ga (Schist-Wekusko suite), succeeded by alluvial-fluvial (Missi Group) to marine (Burntwood Group) sediments after 1.85 Ga. Despite the dominance of juvenile magmatic rocks within the collage, U-Pb zircon age and Nd-isotopic data show that older (>2.2-3.0 Ga) basement fragments were present throughout the development of the Amisk collage. An arc-back-arc system close to an Archean craton is proposed as the most likely tectonic setting during formation and accretion of the Amisk collage from 1.90 to 1.84 Ga. Subsequent continental collision during peak orogeny (1.84-1.81 Ga) is interpreted to have delaminated the lower crust and upper mantle of the collage, preferentially preserving crust of intermediate bulk composition.

Geochemistry of two metavolcanic arc suites from the Central Metasedimentary Belt of the Grenville Province, southeastern Ontario, Canada

1991 ◽  
Vol 28 (9) ◽  
pp. 1429-1443 ◽  
Author(s):  
Luc Harnois ◽  
John M. Moore
Keyword(s):  
Rare Earth ◽  
Rare Earth Elements ◽  
Trace Element ◽  
Partial Melting ◽  
Volcanic Rocks ◽  
Parental Magma ◽  
Major Elements ◽  
Grenville Province ◽  
Element Abundances ◽  
Felsic Rocks

Samples of two subalkaline metavolcanic suites, the Tudor formation (ca. 1.28 Ga) and the overlying Kashwakamak formation, have been analysed for major elements and 27 trace elements (including rare-earth elements). The Tudor formation is tholeiitic and contains mainly basaltic flows, whereas the Kashwakamak formation is calc-alkaline and contains mainly andesitic rocks with minor felsic rocks. The succession has been regionally metamorphosed to upper greenschist – lower amphibolite facies. Trace-element abundances and ratios indicate that rocks of the Tudor and Kashwakamak formations are island-arc type. Geochemical modelling using rare-earth elements, Zr, Ti, and Y indicates that the Tudor volcanic rocks are not derived from a single parental magma through simple fractional crystallization. Equilibrium partial melting of a heterogeneous Proterozoic upper mantle can explain the trace-element abundances and ratios of Tudor formation volcanic rocks. The intermediate to felsic rocks of the Kashwakamak formation appear to have been derived from a separate partial melting event. The data are consistent with an origin of the arc either on oceanic crust or on thinned continental crust, and with accretion of the arc to a continental margin between the time of extrusion of Tudor volcanic rocks and that of Kashwakamak volcanic rocks.

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