Structural development of angular volcanic belts in the Archean Slave Province: Discussion

1990 ◽  
Vol 27 (12) ◽  
pp. 1783-1785
Author(s):  
T. M. Kusky
Keyword(s):  
Structural Development ◽  
Slave Province ◽  
Volcanic Belts

Structural development of angular volcanic belts in the Archean Slave Province

1990 ◽  
Vol 27 (3) ◽  
pp. 403-413 ◽  
Author(s):  
W. K. Fyson
Keyword(s):  
Late Phase ◽  
Length Change ◽  
Structural Development ◽  
Southwestern Part ◽  
Phase Layer ◽  
Slave Province ◽  
Granitoid Rocks ◽  
Transfer Faults ◽  
Volcanic Belts ◽  
Regional Compression

Narrow belts of metavolcanics lying between metasediments and granitoid rocks in the southwestern part of the Archean Slave Province display a distinctive angular map pattern. Steep homoclinal segments, from 10 to over 50 km in length, change strike abruptly at "corners" as if defining large, open, angular folds. Structures near two corners in a belt are not, however, compatible with such folds. Examples include early-phase, layer-parallel foliations in directional sets that are interspersed with one set overprinting the other; mafic dykes of similar contrasting orientations interspersed within basal gneiss; and isoclines in metasediments that deflect rather than wrap around a corner. Additionally, late-phase foliations striking across corners indicate compression that tended to straighten rather than fold the belt.It is suggested that the angular volcanic belts and imposed structures reflect movements on long-lived, crustal-scale faults. A model of development is proposed in which synvolcanic, listric extensional faults and high-angle transfer faults were reactivated as upthrusts during regional compression. Consequent tilting of the volcanics in different directions formed the angular pattern of steep homoclines and guided the development of a succession of folds and foliations.

Geochemical and metallogenic relations in volcanic rocks of the southern Slave Province: implications for late Neoarchean tectonics

2006 ◽  
Vol 43 (12) ◽  
pp. 1835-1857 ◽  
Author(s):  
A M Goodwin ◽  
M B Lambert ◽  
O Ujike
Keyword(s):  
Plate Tectonics ◽  
Early Stage ◽  
Volcanic Rocks ◽  
Volcanic Belt ◽  
Gold Deposits ◽  
Tectonic Plates ◽  
Slave Province ◽  
Volcanogenic Massive Sulphide ◽  
Lode Gold Deposits ◽  
Volcanic Belts

Late Neoarchean volcanic belts in the southern Slave Province include (1) in the east, the Cameron River – Beaulieu River belts, which are characterized by stratigraphically thin, flow-rich, classic calc-alkaline, arc-type sequences with accompanying syngenetic volcanogenic massive sulphide deposits; and (2) in the west, the Yellowknife belt, which is characterized by stratigraphically thick, structurally complex, pyroclastic-rich, adakitic, back-arc basin-type sequences, with accompanying epigenetic lode-gold deposits. The volcanic belt association bears persuasive chemical evidence of subduction-initiated magma generation. However, the greenstone belts, together with coeval matching patterned belts in Superior Province of the southern Canadian Shield, bear equally persuasive evidence of prevailing autochthonous–parautochthonous relations with respect to component stratigraphic parts and to older gneissic basement. The eastern and western volcanic belts in question are petrogenetically ascribed to a "westerly inclined" (present geography) subduction zone(s) that produced shallower (east) to deeper (west), slab-initiated, mantle wedge-generated, parent magmas. This early stage microplate tectonic process involved modest mantle subduction depths, small tectonic plates, and small sialic cratons. In the larger context of Earth's progressively cooling, hence subduction-deepening mantle, this late Neoarchean greenstone belt development (2.73–2.66 Ga) merged with the massive end-Archean tonalite–trondhjemite–granodiorite–granite (TTGG) "bloom" (2.65–2.55 Ga), resulting in greatly enhanced craton stability. Successive subduction-deepening, plate-craton-enlarging stages, with appropriate metallotectonic response across succeeding Proterozoic time and beyond, led to modern-mode plate tectonics.

Archean mafic dyke swarms near the Cameron River and Beaulieu River volcanic belts and their implications for tectonic modelling of the Slave Province, Northwest Territories

1992 ◽  
Vol 29 (10) ◽  
pp. 2226-2248 ◽  
Author(s):  
M. B. Lambert ◽  
R. E. Ernst ◽  
F. Ö. L. Dudás
Keyword(s):  
Isotope Geochemistry ◽  
Flood Basalts ◽  
Nd Isotope ◽  
Slave Province ◽  
Depleted Mantle ◽  
Magmatic Underplating ◽  
Basaltic Magmas ◽  
Dyke Swarms ◽  
Volcanic Belts ◽  
Extensive Involvement

Three dense swarms of Archean mafic dykes, which intrude the Beaulieu River and Cameron River volcanic belts and adjacent granitoid terranes of the Sleepy Dragon Complex and Meander Lake complex in the southern Slave Province, all contain clusters of multiple, parallel-sided "sheeted" dykes. None of the swarms can be convincingly modelled as being part of an ophiolite assemblage. The 3 km by 20+ km Step'nduck dyke complex, comprising about 350 mainly metabasaltic to meta-gabbroic dykes separated by screens of granitoid gneiss (>2750 Ma), represents profuse mafic magmatism in the Meander Lake complex. Dense dyke swarms within the Cameron River belt fed the lavas and are an integral part of the volcanic stratigraphy.All basaltic magmas represented by the volcanic belts, and the dyke sets, are predominantly mantle-derived, fractionated, tholeiites. Nd-isotope geochemistry indicates that they were all contaminated by Archean sialic material. Isotopic systematics are satisfied by mixing of depleted mantle and varying proportions of Sleepy Dragon-type crust.The dyke swarms in the Sleepy Dragon Complex and the Step'nduck swarm record extensional events in Archean continental crust. Possibly they are subsurface equivalents of now-eroded flood basalts that signalled the activity of mantle plumes during Archean times. This hypothesis is consistent with magmatic underplating of continental lithosphere and with extensive involvement of continental material.

Structural development of Topex/Poseidon satellite

1992 ◽  
Author(s):  
MICHAEL LOU ◽  
WALTER TSUHA ◽  
PAUL LARKIN
Keyword(s):  
Structural Development

Proterozoic thermal activity in the Archaean basement of the Disko Bugt region and eastern Nuussuaq, West Greenland: evidence from K-Ar and 40Ar-39Ar mineral age investigations

1999 ◽  
pp. 55-64
Author(s):  
Henrik Rasmussen ◽  
Paul Martin Holm
Keyword(s):  
Structural Development ◽  
Thermal Activity ◽  
Excess Argon ◽  
Original Series ◽  
West Greenland ◽  
Precambrian Rocks ◽  
North Eastern ◽  
The Matrix ◽  
Radiogenic Argon

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Rasmussen, H., & Holm, P. M. (1999). Proterozoic thermal activity in the Archaean basement of the Disko Bugt region and eastern Nuussuaq, West Greenland: evidence from K-Ar and 40Ar-39Ar mineral age investigations. Geology of Greenland Survey Bulletin, 181, 55-64. https://doi.org/10.34194/ggub.v181.5113 _______________ K-Ar and 40Ar-39Ar analyses of amphiboles from Archaean amphibolites and gneisses show that Proterozoic tectono-thermal activity has played an important role in the metamorphic and structural development of the Precambrian rocks around north-eastern Disko Bugt and in eastern Nuussuaq. Proterozoic thermal activity lead to resetting of the K-Ar ages of amphiboles in eastern Nuussuaq, resulting in ages of c. 1750 to 1925 Ma; in the Disko Bugt area the effects are seen in total or partial resetting with K-Ar ages scattering mostly between 2750 and 1870 Ma. Resetting is caused either by total diffusion of earlier accumulated radiogenic argon or by complete recrystallisation of the amphiboles. Archaean 40Ar-39Ar ages obtained from mafic xenoliths within the Atâ tonalite show that not all parts of the area suffered argon loss during Proterozoic reheating. Incorporation of significant proportions of excess argon in some amphiboles is seen from 40Ar-39Ar mineral age spectra obtained for samples from supracrustal rocks and from mafic xenoliths in the Atâ tonalite. Phlogopite phenocrysts from a lamproite stock yielded a K-Ar age of 1764 ± 24 Ma, identical to a previously determined K-Ar age of the matrix phlogopite. These ages probably date the emplacement of the lamproite, and mark the time after which no tectono-thermal events affected the area.

Anton terrane revisited: Late Archean exhumation of a moderate-pressure granulite terrane in the western Slave Province

Geology ◽  
2000 ◽  
Vol 28 (12) ◽  
pp. 1075-1078
Author(s):  
S.J. Pehrsson ◽  
T. Chacko ◽  
M. Pilkington ◽  
M.E. Villeneuve ◽  
K. Bethune
Keyword(s):  
Moderate Pressure ◽  
Slave Province
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