Geology and Geochronology of the Wollaston Lake Fold Belt in Northwestern Manitoba

1975 ◽  
Vol 12 (10) ◽  
pp. 1749-1759 ◽  
Author(s):  
W. Weber ◽  
R. K. Anderson ◽  
G. S. Clark
Keyword(s):  
Igneous Rocks ◽  
Lake Area ◽  
Fold Belt ◽  
Rock Series ◽  
Granitic Gneiss ◽  
Metasedimentary Rocks ◽  
Continental Deposits ◽  
Quartz Monzonite ◽  
Minimum Age ◽  
Hurwitz Group

Recent studies in the northeastern extension of the Wollaston fold belt in Manitoba suggest that Aphebian metasedimentary rocks of the southern Churchill province comprise a geosynclinal facies that is conformably overlain by a platform facies. A possible period of emergence and embryonic Hudsonian tectonism separates this lower sequence from a blanket of continental deposits, which is probably of large regional extent and includes part of the Hurwitz Group in the District of Keewatin.Rubidium–strontium total-rock isochron ages have been obtained for five rock units in the Kasmere Lake area of Manitoba. The ages reveal that the metasedimentary rocks of the Wollaston fold belt are bounded to the east by an Archean complex comprising a differentiated hypersthene-bearing rock series having a minimum age of 2745 ± 124 Ma (87Rb = 1.39 × 10−11 yr−1) and a quartz monzonite unit having a minimum age of 2636 ± 163 Ma.Hudsonian igneous rocks are mostly syn- to post-kinematic. The age of 1855 ± 62 Ma for a quartz monzonite of batholithic dimension coincides with the ages of similar syntectonic Hudsonian intrusions in the Northwest Territories. The age of 1800 ± 60 Ma obtained from a pelitic gneiss unit is a minimum age for the Hudsonian metamorphism and dates the end of the Hudsonian orogeny in this part of the Churchill province. An age of 1941 ± 25 Ma for a granitic gneiss along the western margin of the Wollaston fold belt indicates early or pre-Hudsonian magmatic activity.

Geochronology of Archean and Proterozoic Rocks in the Southern District of Keewatin

1975 ◽  
Vol 12 (1) ◽  
pp. 95-114 ◽  
Author(s):  
R. K. Wanless ◽  
K. E. Eade
Keyword(s):  
Volcanic Rocks ◽  
Southern District ◽  
Quartz Monzonite ◽  
Minimum Age ◽  
First Time ◽  
Hurwitz Group ◽  
Age Determinations

Rb–Sr and U–Pb dating techniques have been utilized to identify and date Archean supracrustal rocks within the Churchill structural province in regions where K–Ar age determinations have recorded only the effects of younger Hudsonian orogeny. The age of emplacement of Archean granodiorite has been established at 2550 m.y., a determination that also provides a minimum age for volcanic rocks intruded by the granodiorite.The overlying Proterozoic Hurwitz Group volcanic rocks have been dated for the first time at 1808 ± 35 m.y. (Upper Aphebian). A post-Hurwitz Group quartz monzonite pluton intruded the granodiorite gneiss at 1772 ± 22 m.y. and the age of the post-tectonic Nueltin Lake Granite has been established at 1700 ± 16 m.y. (Paleohelikian).It is concluded that the Hurwitz Group cannot be correlated with the Huronian succession in Ontario as the Hurwitz Group rocks are 300 to 400 m.y. younger than the Huronian strata.

New structural, metamorphic, and U–Pb geochronological constraints on the Blezardian Orogeny and Yavapai Orogeny in the Southern Province, Sudbury, Canada

2014 ◽  
Vol 51 (8) ◽  
pp. 750-774 ◽  
Author(s):  
Tsilavo Raharimahefa ◽  
Bruno Lafrance ◽  
Douglas K. Tinkham
Keyword(s):  
Inductively Coupled Plasma ◽  
Regional Metamorphism ◽  
Crustal Thickening ◽  
Lake Area ◽  
Southern Province ◽  
Inductively Coupled ◽  
Metasedimentary Rocks ◽  
Minimum Age ◽  
Plasma Mass Spectrometry ◽  
Geochronological Constraints

New structural and geochronological data are presented for two orogenic events, the Blezardian and Yavapai orogenies, which affected the Paleoproterozoic Southern Province near Sudbury, Ontario, Canada. The Southern Province comprises ca. 2452 Ma metavolcanic rocks and metasedimentary rocks of the Huronian Supergroup, which were deposited along the southern margin of the Archean Superior craton during its evolution from a rifted to passive continental margin. Emplacement of the ca. 2415 Ma Creighton pluton during rifting was followed by its deformation and the development of a penetrative gneissic fabric during the ca. 2415 − ca. 2219 Ma Blezardian Orogeny. New laser ablation – inductively coupled plasma – mass spectrometry (LA–ICP–MS) U–Pb zircon ages of 2343 ± 17 and 2344 ± 47 Ma on two granitic dikes that cut this fabric provide a new minimum age of ca. 2.34 Ga for the Blezardian Orogeny. The Sudbury area was then impacted by a large extraterrestrial bolide at ca. 1.85 Ga and deformed during the Penokean Orogeny. The southern part of the Southern Province was later reworked by regional folding and north-directed thrusting during the younger 1.7 Ga Yavapai Orogeny. The 1744 ± 29 Ma Eden Lake Complex was emplaced and deformed during this event, which produced a strong foliation overprinting the complex. The foliation formed at pressures of 2.8–4 kbar (1 kbar = 100 MPa) and temperatures of 540–565 °C and was intruded by a weakly deformed 1704 ± 13 Ma old granitic dike, bracketing the Yavapai event between 1744 ± 29 and 1704 ± 13 Ma in the Sudbury segment of the Southern Province. Crustal thickening associated with the Yavapai event resulted, locally, in minor pressure increases before or during regional metamorphism as revealed by phase equilibria modeling in the Raft Lake area; this evolution may be recorded elsewhere in the Ontario segment of the Southern Province.

Specifics of the Caledonian Collision in the Ol’khon Region (Lake Baikal, Russia)

2021 ◽  
Vol 62 (4) ◽  
pp. 389-400
Author(s):  
V.A. Makrygina
Keyword(s):  
Subduction Zone ◽  
Oceanic Crust ◽  
Lake Baikal ◽  
Siberian Craton ◽  
Island Arc ◽  
Geophysical Data ◽  
Igneous Rocks ◽  
Fold Belt ◽  
Adjacent Part

Abstract —Analysis of geochemical, geochronological, and new geophysical data on metasedimentary and igneous rocks of the Ol’khon region has made it possible to substantiate: (1) the absence of products of the Caledonian suprasubduction magmatism from the adjacent part of the Siberian craton and (2) the presence of a product of this magmatism in the Anga–Talanchan island arc, namely, the Krestovsky massif with gabbro-diorite to granite phases. This suggests subduction of the Paleoasian oceanic crust under the island arc before the collision. The geophysical data showed a steep sinking of the Siberian craton margin. This sinking and the supposed contrary movement and rotation of the Siberian craton prevented the appearance of a subduction zone beneath the craton during the collision but caused the wide development of fault plates in the fold belt at the late collision stage. The residue of oceanic crust slab was pressed out along the fault planes near the surface and formed a row of gabbro-pyroxenite massifs of the Birkhin Complex in the fold belt, where syncollisional granitic melts (Sharanur Complex) formed at the same time. The interaction of two contrasting melts gave rise to the Tazheran and Budun alkaline syenite massifs and alkaline metasomatites of the Birkhin and Ulanganta gabbroid massifs.

Igneous Rock-Series and Mixed Igneous Rocks

1900 ◽  
Vol 8 (5) ◽  
pp. 389-399 ◽  
Author(s):  
Alfred Harker
Keyword(s):  
Igneous Rock ◽  
Igneous Rocks ◽  
Rock Series

scholarly journals Gold-hosting supracrustal rocks on Storø, southern West Greenland: lithologies and geological environment

2007 ◽  
Vol 13 ◽  
pp. 41-44 ◽  
Author(s):  
Christian Knudsen ◽  
Jeroen A.M. Van Gool ◽  
Claus Østergaard ◽  
Julie A. Hollis ◽  
Matilde Rink-Jørgensen ◽  
...  
Keyword(s):  
Volcanic Rocks ◽  
West Greenland ◽  
Metasedimentary Rocks ◽  
Quartz Veins ◽  
Rock Types ◽  
Minimum Age ◽  
Arc Setting ◽  
Basic Volcanic ◽  
Back Arc ◽  
Different Sources

A gold prospect on central Storø in the Nuuk region of southern West Greenland is hosted by a sequence of intensely deformed, amphibolite facies supracrustal rocks of late Mesoto Neoarchaean age. The prospect is at present being explored by the Greenlandic mining company NunaMinerals A/S. Amphibolites likely to be derived from basaltic volcanic rocks dominate, and ultrabasic to intermediate rocks are also interpreted to be derived from volcanic rocks. The sequence also contains metasedimentary rocks including quartzites and cordierite-, sillimanite-, garnet- and biotite-bearing aluminous gneisses. The metasediments contain detrital zircon from different sources indicating a maximum age of the mineralisation of c. 2.8 Ga. The original deposition of the various rock types is believed to have taken place in a back-arc setting. Gold is mainly hosted in garnet- and biotite-rich zones in amphibolites often associated with quartz veins. Gold has been found within garnets indicating that the mineralisation is pre-metamorphic, which points to a minimum age of the mineralisation of c. 2.6 Ga. The geochemistry of the goldbearing zones indicates that the initial gold mineralisation is tied to fluid-induced sericitisation of a basic volcanic protolith. The hosting rocks and the mineralisation are affected by several generations of folding.

Coeval sedimentation, magmatism, and fold-thrust belt development in the Trans-Hudson Orogen: geochronological evidence from the Wekusko Lake area, Manitoba, Canada

1999 ◽  
Vol 36 (2) ◽  
pp. 293-312 ◽  
Author(s):  
Kevin M Ansdell ◽  
Karen A Connors ◽  
Richard A Stern ◽  
Stephen B Lucas
Keyword(s):  
Regional Metamorphism ◽  
Volcanic Rocks ◽  
Sedimentary Rocks ◽  
Detrital Zircons ◽  
Lake Area ◽  
Thrust Belt ◽  
Fold And Thrust Belt ◽  
Minimum Age ◽  
Flin Flon ◽  
Felsic Volcanic

Lithological and structural mapping in the east Wekusko Lake area of the Flin Flon Belt, Trans-Hudson Orogen, suggested an intimate relationship between magmatism, fluvial sedimentation, and initiation of fold and thrust belt deformation. Conventional U-Pb geochronology of volcanic rocks in fault-bounded assemblages provides a minimum age of 1876 ± 2 Ma for McCafferty Liftover back-arc basalts, and ages of between 1833 and 1836 Ma for the Herb Lake volcanic rocks. A rhyolite which unconformably overlies Western Missi Group fluvial sedimentary rocks has complex zircon systematics. This rock may be as old as about 1856 Ma or as young as 1830 Ma. The sedimentary rocks overlying this rhyolite are locally intercalated with 1834 Ma felsic volcanic rocks, and yield sensitive high resolution ion microprobe (SHRIMP) U-Pb and Pb-evaporation detrital zircon ages ranging from 1834 to 2004 Ma. The Eastern Missi Group is cut by an 1826 ± 4 Ma felsic dyke, and contains 1832-1911 Ma detrital zircons. The dominant source for detritus in the Missi Group was the Flin Flon accretionary collage and associated successor arc rocks. The fluvial sedimentary rocks and the Herb Lake volcanic rocks were essentially coeval, and were then incorporated into a southwest-directed fold and thrust belt which was initiated at about 1840 Ma and active until at least peak regional metamorphism.

Rb/Sr Ages and a profile of initial Sr87/Sr86 ratios for plutonic rocks across the Yukon Crystalline Terrane

1976 ◽  
Vol 13 (2) ◽  
pp. 319-330 ◽  
Author(s):  
P. C. Le Couteur ◽  
D. J. Tempelman-Kluit
Keyword(s):  
Quartz Diorite ◽  
Igneous Rocks ◽  
Slow Cooling ◽  
Precambrian Rocks ◽  
Quartz Monzonite ◽  
Plutonic Complex ◽  
Coast Plutonic Complex ◽  
Plutonic Rocks

Nine Rb/Sr apparent ages are reported for igneous rocks of the Yukon Crystalline Terrane. The oldest age (144 m.y.) is from the Triassic? Klotassin quartz diorite and is thought to be a hybrid age that probably reflects the effects of younger intrusives on rocks at least 190 m.y. old. Five ages of about 100 m.y. presumably reflect the cooling of the Coffee Creek quartz monzonite. K/Ar ages for this event are slightly younger than the Rb/Sr ages, suggesting slow cooling. Rb/Sr ages of 53 and 67 m.y. were obtained for the Ruby Range batholith and an age of 61–67 m.y. for the Nisling Range alaskite. The Rb/Sr ages obtained generally confirm recently determined K/Ar ages. There is a regional decrease in initial Sr87/Sr86 ratios, southwestward across the Yukon Crystalline Terrane. This may mean that Precambrian rocks extend under the Yukon Crystalline Terrane, but are absent under the adjoining Coast Plutonic Complex.

Rb–Sr geochronology and metamorphic history of Proterozoic to early Archean rocks north of the Cape Smith Fold Belt, Quebec

1987 ◽  
Vol 24 (4) ◽  
pp. 813-825 ◽  
Author(s):  
Ronald Doig
Keyword(s):  
Volcanic Rocks ◽  
Granitic Rocks ◽  
Iron Formation ◽  
Fold Belt ◽  
Metasedimentary Rocks ◽  
Metamorphic History ◽  
The North ◽  
Basement Rocks ◽  
History Of ◽  
Wide Zone

The Churchill Province north of the Proterozoic Cape Smith volcanic fold belt of Quebec may be divided into two parts. The first is a broad antiform of migmatitic gneisses (Deception gneisses) extending north from the fold belt ~50 km to Sugluk Inlet. The second is a 20 km wide zone of high-grade metasedimentary rocks northwest of Sugluk Inlet. The Deception gneisses yield Rb–Sr isochron ages of 2600–2900 Ma and initial ratios of 0.701–0.703, showing that they are Archean basement to the Cape Smith Belt. The evidence that the basement rocks have been isoclinally refolded in the Proterozoic is clear at the contact with the fold belt. However, the gneisses also contain ubiquitous synclinal keels of metasiltstone with minor metapelite and marble that give isochron ages less than 2150 Ma. These ages, combined with low initial ratios of 0.7036, show that they are not part of the basement, as the average 87Sr/86Sr ratio for the basement rocks was about 0.718 at that time.The rocks west of Sugluk Inlet consist mainly of quartzo-feldspathic sediments, quartzites, para-amphibolites, marbles, and some pelite and iron formation. In contrast to the Proterozoic sediments in the Deception gneisses, these rocks yield dates of 3000–3200 Ma, with high initial ratios of 0.707–0.714. These initial ratios point to an age (or a provenance) much greater than that of the Archean Deception gneisses. The rocks of the Sugluk terrain are intruded by highly deformed sills of granitic rocks with ages of about 1830 Ma, demonstrating again the extent and severity of the Proterozoic overprint. The eastern margin of this possibly early Archean Sugluk block is a discontinuity in age, lithology, and geophysical character that could be a suture between two Archean cratons. It is not known if such a suturing event is of Archean age, or if it is related to the deformation of the Cape Smith Fold Belt.Models of evolution incorporating both the Cape Smith Belt and the Archean rocks to the north need to account for the internal structure of the fold belt, the continental affinity of many of the volcanic rocks, the continuity of basement around the eastern end of the belt, and the increase in metamorphism through the northern part of the belt into a broad area to the north. The Cape Smith volcanic rocks may have been extruded along a continental rift, parallel to a continental margin at Sugluk. Continental collison at Sugluk would have thrust the older and higher grade Sugluk rocks over the Deception gneisses, produced the broad Deception antiform, and displaced the Cape Smith rocks to the south in a series of north-dipping thrust slices.

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