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.

Temporal distribution of granitoid plutonic rocks in the Archean Slave Province, northwest Canadian Shield

1992 ◽  
Vol 29 (10) ◽  
pp. 2186-2199 ◽  
Author(s):  
O. van Breemen ◽  
W. J. Davis ◽  
J. E. King
Keyword(s):  
Continental Margin ◽  
Temporal Distribution ◽  
Lake Area ◽  
Margin Setting ◽  
General Terms ◽  
Slave Province ◽  
Age Variation ◽  
Granitoid Rocks ◽  
Plutonic Rocks ◽  
Granitoid Gneisses

Granitoid rocks in the Slave Province consist of 4.0–2.8 Ga granitoid gneisses that predate the 2.71–2.65 Ga volcanic and turbiditic rocks of the Yellowknife Supergroup and 2.70–2.58 Ga granitoid plutons that intrude the Yellowknife Supergroup. U–Pb zircon ages and Nd and Pb isotopic data indicate that the older granitoids are restricted to the western part of the Slave Province. Granitoid gneisses in the eastern Slave Province, previously suspected to predate the Yellowknife Supergroup, are similar in age to the volcanic rocks.In this paper, the results of a detailed geochronological study of plutonic rocks of the Contwoyto Lake – Nose Lake area of the northcentral Slave Province are reviewed and integrated with the available age data base for plutonic rocks elsewhere in the Slave Province. The data indicate that the timing of the later (<2.7 Ga) plutonism is bimodal, consisting of two distinct magmatic periods separated by approximately 20 Ma of apparent magmatic quiescence. The first period was synvolcanic, dating from 2695 to 2650 Ma. The second period, during which more than 80% of the granitoids presently exposed in the Slave Province were intruded, lasted from 2625 to 2580 Ma, spanning the major Archean deformation events, Syndeformation granitoids, with ages between 2625 and 2595 Ma, are dominantly diorite and tonalité in composition. Late- to post-deformation granitoid rocks, with ages between 2605 and 2580 Ma, range in composition from megacrystic biotite granodiorite to two-mica granite. In general terms, the compositions of the granitoid plutons vary in time from dominantly metaluminous to more strongly peraluminous.Present data show no obvious regional age variation among the younger granitoid rocks across the province. This apparent absence of diachroneity has important implications for models interpreting the magmatism as having evolved in a continental-margin setting, because the extent of contemporaneous plutonism is more than 400 km across strike, considerably broader than in most Mesozoic continental-margin batholiths.

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.

Reorientation of structures near granitic plutons and orthogonal lineaments, Russell Lake supracrustal domain, southwestern Slave Province

1991 ◽  
Vol 28 (1) ◽  
pp. 126-135 ◽  
Author(s):  
W. K. Fyson ◽  
V. A. Jackson
Keyword(s):  
Strike Slip ◽  
Slave Province ◽  
Metavolcanic Rocks ◽  
Regional Compression

A complex array of folds and cleavages in metasedimentary and metavolcanic rocks in the Russell Lake domain could reflect regional compression recurrently reoriented across crustal lineaments. Several generations of steeply inclined folds trending northward across the domain curve into or interfere with folds parallel to margins of bordering granite batholiths aligned orthogonally northwest (LNW) and northeast (LNE). Sets of later subvertical cleavages strike northward, northwest parallel and oblique to LNW, and northeastward subparallel to LNE. The cleavages extend beyond the aligned margins, indicating that the association with the granites is indirect.The arrangements of folds and cleavages are consistent with intermittent redirection of subhorizontal compression of cover rocks perpendicular to orthogonal, steep crustal fractures that were intruded by syndeformational granitic plutons. Additionally, overturning of folds near plutons suggests local reorientation of compression near shallow-dipping margins. Following folding, further reorientations resulted in reversals in strike-slip bedding shear and cleavage sets locally symmetric about fold limbs.

William James: The Late Phase

1998 ◽  
Vol 43 (11) ◽  
pp. 760-761 ◽  
Author(s):  
James William Anderson
Keyword(s):  
William James ◽  
Late Phase

Effects of metoprolol on hypoxia- and isoflurane-induced late-phase preconditioning

2011 ◽  
Vol 59 (S 01) ◽  
Author(s):  
A Goetzenich ◽  
A Moza ◽  
A Roehl ◽  
S Arnold ◽  
M Hein
Keyword(s):  
Late Phase
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