Zircon U–Pb ages from the Kakagi Lake area, Wabigoon Subprovince, northwest Ontario

1982 ◽  
Vol 19 (6) ◽  
pp. 1235-1245 ◽  
Author(s):  
Donald W. Davis ◽  
Garth R. Edwards
Keyword(s):  
Early Stage ◽  
Volcanic Rocks ◽  
Age Difference ◽  
Lake Area ◽  
Air Abrasion ◽  
High Gradient Magnetic Separation ◽  
Pyroclastic Rocks ◽  
Gneiss Domes ◽  
The North ◽  
Lake Formation

Five rocks have been dated from the Kakagi Lake area of the Wabigoon Subprovince by means of U–Pb analysis of zircons. Using the techniques of air abrasion and high gradient magnetic separation, zircon fractions from four of the samples have been made concordant.Stratigraphy in the Kakagi Lake area consists of tholeiitic basalts of the Snake Bay and Katimiagamak Lake Formations overlain by mainly calc-alkalic pyroclastic rocks of the Kakagi Lake Group. A felsic tuff collected from the top of the Kakagi Lake Group is dated at [Formula: see text]. This group is intruded by differentiated ultramafic to mafic sills. The age for a gabbro pegmatite from the lowermost sill near the base of the group is [Formula: see text]. The Katimiagamak Lake Formation is intruded by tonalite of the Sabaskong batholith, which gives an age of [Formula: see text]. The tonalite is flanked by the Phinney–Dash Lakes Complex of subvolcanic stocks and dacite to rhyolite volcanic rocks that intrude and overlie the Katimiagamak Lake Formation. A dacite from the complex gives an age of 2727.7 ± 1.1 Ma. A porphyry complex to the north, the Berry Creek Complex, is separated from the other rocks by the Pipestone – Cameron Lakes Fault and gives an age of [Formula: see text] on a quartz porphyry.The predominantly mafic to intermediate pyroclastic rocks of the Kakagi Lake Group are interpreted to be approximately contemporaneous with the Kakagi sills and to have evolved from the basalt magmatism. Tonalitic rocks of the Sabaskong batholith and the Phinney–Dash Lakes Complex were derived from partial melting of the hydrous lower basalts during the early stage of regional granitoid diapirism. Because of the large age difference between the lowermost sill and the felsic tuff from the top of the Kakagi Lake Group, it is suggested that this formation is not part of the group. It and the Berry Creek Complex were formed from felsic melts separating from rising granitoid gneiss domes during a slightly later stage of regional granitoid diapirism that may have resulted from the reactivation of a predominantly sialic basement by the accumulation of heat over and adjacent to the mantle sources of the basalt.

Zircon U–Pb ages from the Wabigoon–Manitou Lakes region, Wabigoon Subprovince, northwest Ontario

1982 ◽  
Vol 19 (2) ◽  
pp. 254-266 ◽  
Author(s):  
D. W. Davis ◽  
C. E. Blackburn ◽  
T. E. Krogh
Keyword(s):  
Experimental Error ◽  
Volcanic Rocks ◽  
Calc Alkaline ◽  
Air Abrasion ◽  
New Techniques ◽  
High Gradient Magnetic Separation ◽  
Pyroclastic Rocks ◽  
High Iron ◽  
Minimum Age ◽  
Northwest Ontario

Three distinct stratigraphic units have been recognized in the Crow Lake – Savant Lake belt. These are a basal unit consisting of high magnesium tholeiitic flows, a middle unit consisting mostly of tholeiitic to calc-alkaline pyroclastic rocks and flows, and an upper unit of high iron tholeiitic flows.A zircon U–Pb study has been carried out on seven rocks from the Wabigoon–Manitou Lakes region of this belt. In the Manitou Lakes area, a minimum age of 2755 Ma on a porphyry pluton intruded into the Wapageisi Volcanics gives a minimum age for the high magnesium tholeiitic sequence.A trondhjemite phase of the Atikwa batholith near Wabigoon Lake that is dated at 2732.2 ± 2.9 Ma has the same age within experimental error as a rhyolite flow from the Lower Wabigoon Volcanics in the same area that is dated at [Formula: see text]. However, a trondhjemite phase of the Atikwa batholith at Eagle Lake that is dated at [Formula: see text] is distinctly younger than a dacite flow collected nearby from the Lower Wabigoon Volcanics that is dated at [Formula: see text]. Both these volcanic rocks are from the middle mixed sequence.A rhyolite tuff from the Boyer Lake Volcanics, from the upper high iron tholeiitic sequence, gives a relatively young age of [Formula: see text]. An age of 2695 ± 3.6 Ma on the post-tectonic Taylor Lake stock gives a minimum age for the end of deformation.Several new techniques such as air abrasion with pyrite, crushing and abrasion, and high gradient magnetic separation have been employed to reduce the discordance of zircons. Of these, the air abrasion technique has proven to be the most effective.

U–Pb ages and tectonic significance of late Archean alkalic magmatism and nonmarine sedimentation: Timiskaming Group, southern Abitibi belt, Ontario

1991 ◽  
Vol 28 (4) ◽  
pp. 489-503 ◽  
Author(s):  
F. Corfu ◽  
S. L. Jackson ◽  
R. H. Sutcliffe
Keyword(s):  
Greenstone Belt ◽  
Early Stage ◽  
Sedimentary Rocks ◽  
Detrital Zircons ◽  
Geochemical Data ◽  
Lake Area ◽  
Quartz Porphyry ◽  
Bear Lake ◽  
Lake Formation ◽  
Dominant Period

The paper presents U–Pb ages for zircons of the calc-alkalic to alkalic igneous suite and associated alluvial–fluvial sedimentary rocks of the Timiskaming Group in the late Archean Abitibi greenstone belt, Superior Province. The Timiskaming Group rests unconformably on pre-2700 Ma komatiitic to calc-alkalic volcanic sequences and is the expression of the latest stages of magmatism and tectonism that shaped the greenstone belt. An age of 2685 ± 3 Ma for the Bidgood quartz porphyry, an age of about 2685–2682 Ma for a quartz–feldspar porphyry clast in a conglomerate, and ages ranging from 2686 to 2680 Ma for detrital zircons in sandstones appear to reflect an early stage in the development of the Timiskaming Group. The youngest detrital zircons in each of three sandstones at Timmins, Kirkland Lake, and south of Larder Lake define maximum ages of sedimentation at about 2679 Ma; the latter sandstone is cut by a porphyry dyke dated by titanite at [Formula: see text], identical to the 2677 ± 2 Ma age for a volcanic agglomerate of the Bear Lake Formation north of Larder Lake. Similar ages have previously been reported for syenitic to granitic plutons of the region. The dominant period of Timiskaming sedimentation and magmatism was thus 2680–2677 Ma. Xenocrystic zircons found in a porphyry and a lamprophyre dyke have ages of 2750–2720 Ma, which correspond to the ages of the oldest units in the belt, predating the volumetrically dominant ca. 2700 Ma greenstone sequences. The presence of these xenocrysts and the onlapping of the Timiskaming Group on all earlier lithotectonic units of the southern Abitibi belt support the concept that the 2700 Ma ensimatic sequences were thrust onto older assemblages during a phase of compression that culminated with the generation of tonalite and granodiorite at about 2695–2688 Ma. Published geochemical data for the Timiskaming igneous suite, notably the enrichments in large-ion lithophile elements and light rare-earth elements and the relative depletion of Nb, Ta, and Ti compare with the characteristics of suites at modern convergent settings such as the Eolian and the Banda arcs and are consistent with generation of the melts from deep metasomatized mantle in the final stages of, or after cessation of, subduction. Late- and post-Timiskaming compression caused north-directed thrusting and folding. Turbiditic sedimentary units of the Larder Lake area which locally structurally overly the alluvial–fluvial sequence and were earlier thought to be part of the Timiskaming Group, appear to be older "flyschoid" sequences, possibly correlative with sedimentary rocks deposited in the Porcupine syncline at Timmins between 2700 and 2690 Ma.

Age of the Bowen Island Group, southwestern Coast Mountains, British Columbia

1990 ◽  
Vol 27 (11) ◽  
pp. 1456-1461 ◽  
Author(s):  
R. M. Friedman ◽  
J. W. H. Monger ◽  
H. W. Tipper
Keyword(s):  
British Columbia ◽  
Middle Jurassic ◽  
Volcanic Rocks ◽  
Sedimentary Facies ◽  
Lower Jurassic ◽  
Coast Mountains ◽  
The North ◽  
Metavolcanic Rocks ◽  
Lake Formation ◽  
Island Group

A new U–Pb date of [Formula: see text] for foliated felsic metavolcanic rocks of the Bowen Island Group, from Mount Elphinstone in the southwesternmost Coast Mountains of British Columbia, indicates that there the age of this hitherto undated unit is early Middle Jurassic. These rocks grade along strike to the north-northwest into a more sedimentary facies, which north of Jervis Inlet contains a probable Sinemurian (Lower Jurassic) ammonite. The Bowen Island Group thus appears to include Lower and Middle Jurassic rocks and to be coeval in part with volcanic rocks of the Bonanza Formation on Vancouver Island to the west and the Harrison Lake Formation within the central Coast Mountains 75 km to the east.

ARCHAEAN SEDIMENTARY ROCKS OF NORTH SPIRIT LAKE AREA, NORTHWESTERN ONTARIO

1965 ◽  
Vol 2 (6) ◽  
pp. 622-647 ◽  
Author(s):  
J. A. Donaldson ◽  
G. D. Jackson
Keyword(s):  
Volcanic Rocks ◽  
Sedimentary Rocks ◽  
Sole Source ◽  
Lake Area ◽  
Red Lake ◽  
Sedimentary Sequences ◽  
The North ◽  
Northwestern Ontario ◽  
History Of ◽  
Granitoid Rocks

Archaean sedimentary rocks of the North Spirit Lake area show little evidence of having been derived predominantly from associated Archaean volcanic rocks. Instead, compositions of the sediments reflect significant sedimentary and (or) granitoid provenance. A remarkably high content of clastic quartz in thick units of sandstone and conglomerate suggests either reworking of older quartzose sediments, or reduction of the labile constituents in quartz-rich granitoid rocks through prolonged weathering and rigorous transport. Observations for other sedimentary sequences in the region between Red Lake and Lansdowne House suggest that the North Spirit sediments are not unique in the Superior Province. Quartzose sandstones commonly are regarded as atypical of the Archaean, but such rocks arc abundant in northwestern Ontario. Frameworks of many Archaean greywackes actually are richer in quartz than typical greywackes from numerous Proterozoic and Phanerozoic sequences.The concept of rapidly rising volcanic arcs as the sole source of Archaean sedimentary detritus is rejected for the North Spirit area. The volcanies, rather than representing relicts of protocontinents, probably record events removed from initial volcanism in the history of the earth by one or more orogenic cycles. Major unconformities may therefore exist not only between sedimentary and volcanic units, but also between these units and older granitoid rocks.

Tip Top Hill volcanics: Late Cretaceous Kasalka Group rocks hosting Eocene epithermal base- and precious-metal veins at Owen Lake, west-central British Columbia

1992 ◽  
Vol 29 (5) ◽  
pp. 854-864 ◽  
Author(s):  
Craig H. B. Leitch ◽  
C. T. Hood ◽  
Xiao-Lin Cheng ◽  
A. J. Sinclair
Keyword(s):  
British Columbia ◽  
Late Cretaceous ◽  
Upper Cretaceous ◽  
Volcanic Rocks ◽  
Lake Area ◽  
Vein Deposit ◽  
Type Area ◽  
Lake Formation ◽  
Host Rocks ◽  
Polymictic Conglomerate

Rocks hosting the Silver Queen epithermal Au–Ag–Zn–Pb–Cu vein deposit near Owen Lake, British Columbia, belong to the Tip Top Hill volcanics. They are lithologically similar to the informally named Upper Cretaceous Kasalka Group rocks exposed in the type area at Tahtsa Lake, 75 km southwest of the deposit, and at Mount Cronin, 100 km northwest of the deposit. The Kasalka Group rocks in the Tahtsa Lake area give questionable dates of 105 ± 5 Ma by K–Ar on whole rock but are cut by intrusions dated at 83.8 ± 2.8 Ma by K–Ar on biotite. The sequence at the Silver Queen deposit includes a polymictic conglomerate, followed upward by felsic fragmental rocks and a thick porphyritic andesite flow and sill unit, cut by microdiorite and quartz–feldspar porphyry intrusions. The porphyritic andesite and the microdiorite have been dated as Late Cretaceous (78.3 ± 2.7 and 78.7 ± 2.7 Ma, respectively, by K–Ar on whole rock), close to previous dates for these rocks (77.1 ± 2.7 and 75.3 ± 2.0 Ma, respectively). The quartz–feldspar porphyry intrudes the porphyritic andesites but has an older U–Pb zircon date of 84.6 ± 0.2 Ma, probably due to underestimation of the true age of the host rocks by the K–Ar whole-rock method. Later dykes correlate with younger volcanic rocks belonging to the Ootsa Lake and Endako groups. Eocene pre- and postmineral plagioclase-rich dykes (51.9 ± 1.8 to 51.3 ± 1.8 Ma) and late diabase dykes (50.4 ± 1.8 Ma; all by K–Ar on whole rock) may be correlative with trachyandesite volcanics of the Goosly Lake Formation, part of the Eocene Endako Group. These volcanics have been dated elsewhere at 55.6 ± 2.5 to 48.8 ± 1.8 Ma by K–Ar on whole rock and biotite, respectively. Mineralization at Silver Queen is therefore similar in age to, but slightly younger than, the producing Equity mine located 30 km to the northeast, which is estimated at 58.5 ± 2.0 Ma by K–Ar on whole rock.

An Archean metamorphic core complex in the southern Slave Province: basement–cover structural relations between the Sleepy Dragon Complex and the Yellowknife Supergroup

1992 ◽  
Vol 29 (10) ◽  
pp. 2133-2145 ◽  
Author(s):  
Donald T. James ◽  
James K. Mortensen
Keyword(s):  
Regional Metamorphism ◽  
Volcanic Rocks ◽  
Lake Area ◽  
Metasedimentary Rocks ◽  
Kinematic Indicators ◽  
The North ◽  
Slave Province ◽  
Gneiss Granite ◽  
History Of ◽  
Metamorphic Core

Archean rocks in the Fenton Lake – Brown Lake area, southern Slave Province, are subdivided into two lithotectonic domains: a supracrustal domain, which consists mainly of the Archean Yellowknife Supergroup, and a gneiss–granite domain. The latter is composed of gneissic and metaigneous rocks of the Sleepy Dragon Complex, determined to be basement to the Yellowknife Supergroup, and granite plutons, including the 2641 ± 3.5 Ma Suse Lake granite and the 2583.5 ± 1 Ma Morose Granite. Volcanic rocks of the Cameron River Belt and greywacke–mudstone turbiditic metasedimentary rocks of the Burwash Formation constitute the supracrustal domain.A late Archean, amphibolite- to greenschist-facies, ductile to local brittle, high-strain zone separates the domains. Kinematic indicators demonstrate that the zone experienced two kinematically opposed episodes of displacement. The older episode involved pre- to synthermal peak thrusting of the supracrustal rocks over the gneiss–granite domain. Thrusting is kinematically and temporally consistent with late Archean, pre- to synthermal peak, regional contractional deformation. Structural and metamorphic relations and kinematic indicators suggest that thrusting and regional contraction were followed shortly by intrusion of the peraluminous Morose Granite and thereafter by a late syn- to post-thermal peak episode of extension, resulting in tectonic unroofing of the gneiss–granite domain.The sequential history of contraction and attendant regional metamorphism, granite intrusion, and, ultimately, extensional collapse, which is documented in the Archean rocks in the area, is a common feature of Phanerozoic collisional orogens. Moreover, the tectonic history of the gneiss–granite domain is broadly similar to the evolution of metamorphic core complexes in the North American Cordillera.

Isotopic studies of ore-leads of the circum-Kisseynew volcanic belt of Manitoba and Saskatchewan

1978 ◽  
Vol 15 (7) ◽  
pp. 1112-1121 ◽  
Author(s):  
D. F. Sangster
Keyword(s):  
Volcanic Rocks ◽  
Volcanic Belt ◽  
Massive Sulfide ◽  
Good Evidence ◽  
Lake Area ◽  
Sulfide Deposits ◽  
North West ◽  
The North ◽  
Isotopic Abundances ◽  
Host Rocks

Volcanic rocks, distributed to the north, west, and south of the Kisseynew gneissic belt in Manitoba and Saskatchewan, define a crescent-shaped belt herein informally referred to as the 'circum-Kisseynew volcanic belt'. Field relationships lead to the conclusion that the flanking volcanics are correlative with, and grade basinward to, greywackes and shales.Nearly 30 volcanogenic massive sulfide deposits, interpreted as coeval with their host rocks, are distributed throughout the circum-Kisseynew volcanic belt. Lead isotopic abundances in a representative number of these deposits are, apart from 204-error, relatively homogeneous in composition and model lead ages determined from these isotopic ratios fall, for the most part, between 1700 and 1900 Ma. This is regarded as good evidence that the circum-Kisseynew volcanic belt, as well as its greywacke equivalent, is largely Aphebian in age.Model lead ages for sulfide deposits from the entire circum-Kisseynew volcanic belt, with one exception, agree well with recent Rb–Sr and U–Pb age determinations from the southern portion of the belt. Reasons for the exception, in the Hanson Lake area, are discussed in some detail.

U–Pb zircon ages for the Rice Lake area, southeastern Manitoba

1989 ◽  
Vol 26 (1) ◽  
pp. 23-30 ◽  
Author(s):  
A. Turek ◽  
R. Keller ◽  
W. R. Van Schmus ◽  
W. Weber
Keyword(s):  
Greenstone Belt ◽  
Volcanic Rocks ◽  
Quartz Diorite ◽  
Granitic Rocks ◽  
Lake Area ◽  
The South ◽  
Metasedimentary Rocks ◽  
The North ◽  
Felsic Volcanic ◽  
Felsic Volcanic Rocks

The Archean Rice Lake greenstone belt in southeastern Manitoba is made up of mafic to felsic volcanic rocks and associated intrusive and metasedimentary rocks. The belt is flanked to the north by the Wanipigow River granitic complex and to the south by the Manigotagan gneissic belt. The Ross River quartz diorite pluton is intrusive into the centre of the greenstone belt. U–Pb zircon ages indicate a major volcanic and plutonic event in the area at 2730 Ma. Ages for two volcanic units of the Rice Lake Group are 2731 ± 3 and 2729 ± 3 Ma. The Ross River pluton yields an age of 2728 ± 8 Ma and the Gunnar porphyry gives an age of 2731 ± 13 Ma; both intrude rocks of the Rice Lake Group. Granitic rocks of the Wanipigow River granitic complex give ages of 2731 ± 10 and 2880 ± 9 Ma, while a post-tectonic granite in the Manigotagan gneissic belt has an age of 2663 ± 7 Ma.

Petrology and tectonic significance of Gates Formation (early Cretaceous) sediments in northeast British Columbia

1986 ◽  
Vol 23 (2) ◽  
pp. 129-141 ◽  
Author(s):  
Dale Leckie
Keyword(s):  
Mineral Content ◽  
Volcanic Rocks ◽  
Foreland Basin ◽  
Rocky Mountain ◽  
Source Area ◽  
Source Rocks ◽  
Sediment Sources ◽  
The North ◽  
Lake Formation ◽  
Tectonic Significance

Moosebar–Gates sandstones are predominantly litharenites, with some feldspathic litharenites. Both the light- and heavy-mineral suites indicate a mixed source characterized by clastic and carbonate sedimentary rocks, acidic to intermediate plutonic and volcanic igneous rocks, and metamorphic rocks. The sediment sources all fall within a recycled orogenic provenance grouping. Histograms showing stratigraphic variation of mineral content do not indicate any significant progressive unroofing of more deeply buried source rocks.The source area was very extensive regionally and extended well into the Omineca Crystalline Belt and eastern margins of the Intermontane Belt. Zebraic chalcedony was derived from evaporitic rocks of the Charlie Lake Formation, situated east of the Rocky Mountain Trench. Kyanite and almandine garnet were probably derived from the Omineca Crystalline Belt west of the Rocky Mountain Trench. Regional paleoslope dipped towards the north-northwest. Restoration of strike-slip on the Rocky Mountain Trench places potential source areas to the south of the depocentre; this supports paleoslope data. During Moosebar–Gates time the Tenakihi Group in the Omineca Crystalline Belt would have been hundreds of kilometres south of its present location and south of the study area, where it could have provided sediment. Volcanic rocks were derived from west of the Rocky Mountain Trench. Source rocks in the Omineca Crystalline Belt were being eroded as early as late early Albian and providing sediment into the foreland basin to the east.

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