K-Ar Dating of the 'Cork' (Burwash Creek) Cu-Mo Prospect, Burwash Landing Area, Yukon Territory

1972 ◽  
Vol 9 (7) ◽  
pp. 918-921 ◽  
Author(s):  
P. A. Christopher ◽  
W. H. White ◽  
J. E. Harakal
Keyword(s):  
Yukon Territory ◽  
Canadian Cordillera ◽  
Early Tertiary ◽  
Apparent Age ◽  
Radiometric Determination

A 26 ± 0.3 m.y. mean age was determined for quartz latite porphyry near Burwash Creek, Yukon Territory. This apparent age for mineralized porphyry represents the youngest documented porphyry prospect in the Canadian Cordillera. Cretaceous ages determined for Kluane Range intrusions agree with geologic evidence, and early Tertiary ages from the Ruby Range batholith agree with a previous radiometric determination.

Evidence for a 55–50 ka (early Wisconsin) glaciation of the Cordilleran ice sheet, Yukon Territory, Canada

2007 ◽  
Vol 68 (1) ◽  
pp. 141-150 ◽  
Author(s):  
Brent C. Ward ◽  
Jeffrey D. Bond ◽  
John C. Gosse
Keyword(s):  
Ice Sheet ◽  
Yukon Territory ◽  
Canadian Cordillera ◽  
Aleutian Low ◽  
Climatic Forcing ◽  
Apparent Contrast ◽  
Oxygen Isotope Stage ◽  
Source Areas ◽  
Cordilleran Ice Sheet ◽  
Exposure Ages

AbstractCosmogenic 10Be ages on boulders of 54–51 ka (n=4) on a penultimate Cordilleran ice sheet (CIS) drift confirm that Marine Oxygen Isotope Stage (MIS) 4 (early Wisconsin) glaciation was extensive in parts of Yukon Territory, the first confirmed evidence in the Canadian Cordillera. We name the glaciation inferred from the mapped and dated drift the Gladstone. These results are in apparent contrast to the MIS 6 (Illinoian) age of the penultimate Reid glaciation to the east in central Yukon but are equivalent to exposure ages on MIS 4 drift in Alaska. Contrasting penultimate ice extents in Yukon requires that different source areas of the northern CIS in Yukon responded differently to climatic forcing during glaciations. The variation in glacier extent for different source areas likely relates to variation in precipitation during glaciation, as the northern CIS was a precipitation-limited system. Causes for a variation in precipitation remain unclear but likely involve the style of precipitation delivery over the St. Elias Mountains possibly related to variations in the Aleutian low.

Three-dimensional seismic crustal structure of the Monashee hinterland core complex on the Lithoprobe Southern Canadian Cordillera Transect

1995 ◽  
Vol 32 (10) ◽  
pp. 1531-1540 ◽  
Author(s):  
Kris Vasudevan ◽  
Frederick A. Cook ◽  
Rolf Maier
Keyword(s):  
Crustal Structure ◽  
Complex Geometry ◽  
Three Dimensional ◽  
Canadian Cordillera ◽  
Metamorphic Complex ◽  
Migration Process ◽  
The South ◽  
Core Complex ◽  
South Central ◽  
Early Tertiary

Three-dimensional seismic coverage in an approximately 12 km × 12 km area of the southern Monashee metamorphic complex in the south-central portion of the Canadian Cordillera reveals a complex geometry to the Mesozoic–early Tertiary contractional Monashee décollement. Data were acquired as part of the Lithoprobe Southern Canadian Cordillera Transect where two approximately perpendicular lines intersected on the south flank of the Monashee mountains in the hinterland of the Cordillera. Stacks of traces within 100 m × 100 m bins are nominally 6-fold, but range from zero to 108-fold due to the crooked nature of the lines. Both migrated and unmigrated data have been examined for interpretation, but the highly variable data quality and discontinuous reflectivity cause excessive added noise during the migration process.

Alternative Interpretations for the Casino Complex and Klotassin Batholith in the Yukon Crystalline Terrane

1975 ◽  
Vol 12 (11) ◽  
pp. 1910-1916 ◽  
Author(s):  
Colin I. Godwin
Keyword(s):  
Porphyry Copper ◽  
Yukon Territory ◽  
Metamorphic Complex ◽  
Early Tertiary ◽  
Molybdenum Deposit ◽  
Two Samples

A small part of the Klotassin batholith, that intrudes the Yukon Metamorphic Complex, has been studied in detail near the Casino porphyry copper–molybdenum deposit, Yukon Territory. Eleven potassium–argon model ages, including concordant biotite and hornblende ages, indicate a mid-Cretaceous (100 Ma) age for this batholith. All ages are indistinguishable statistically. This age, therefore, is interpreted as the age of emplacement of the Klotassin batholith. Older dates can be expected from rocks of the Yukon Metamorphic Complex, the Carmacks batholith, and Aishihik batholith.The Casino complex, host to the Casino deposit, is dated at latest-Cretaceous (70 Ma), based on potassium–argon model ages from two samples of biotite. The complex is clearly intrusive into and younger than the Klotassin batholith. Previously, this unit was interpreted as Early Tertiary. Possibly the several so called Early Tertiary volcanic and hypabyssal rocks in Yukon are not strictly contemporaneous.

Paleomagnetic and geobarometric study of the mid-Cretaceous Whitehorse Pluton, Yukon Territory

1997 ◽  
Vol 34 (10) ◽  
pp. 1379-1391 ◽  
Author(s):  
M. J. Harris ◽  
D. T. A. Symons ◽  
W. H. Blackburn ◽  
C. J. R. Hart
Keyword(s):  
United States ◽  
British Columbia ◽  
Crystallization Temperature ◽  
Remanent Magnetization ◽  
Average Rate ◽  
Yukon Territory ◽  
Canadian Cordillera ◽  
The North ◽  
North American Craton ◽  
High Level

This is the first of several Lithoprobe paleomagnetic studies underway to examine geotectonic motions in the northern Canadian Cordillera. Except for one controversial study, estimates for terranes underlying the Intermontane Belt in the Yukon have been extrapolated from studies in Alaska, southern British Columbia, and the northwestern United States. The Whitehorse Pluton is a large unmetamorphosed and undeformed tonalitic body of mid-Cretaceous age (~112 Ma) that was intruded into sedimentary units of the Whitehorse Trough in the Stikinia terrane. Geothermobarometric estimates for eight sites around the pluton indicate that postmagnetization tilting has been negligible since cooling through the hornblende-crystallization temperature and that the pluton is a high-level intrusion. Paleomagnetic measurements for 22 of 24 sites in the pluton yield a well-defined characteristic remanent magnetization (ChRM) direction that is steeply down and northwards. The ChRM direction gives a paleopole of 285.5°E, 81.7°N (dp = 53°, dm = 5.7°). When compared with the 112 Ma reference pole for the North American craton, this paleopole suggests that the northern Stikinia terrane has been translated northwards by 11.0 ± 4.8° (1220 ± 530 km) and rotated clockwise by 59 ± 17°. Except for an estimate from the ~70 Ma Carmacks Group volcanics, this translation and rotation estimate agrees well with previous estimates for units in the central and southern Intermontane Belt. They suggest that the terranes of the Intermontane Belt have behaved as a fairly coherent unit since the Early Cretaceous, moving northward at a minimum average rate of 2.3 ± 0.4 cm/a between ~140 and ~45 Ma.

New occurrences of two Lower Devonian graptolites from northern Yukon

1979 ◽  
Vol 16 (5) ◽  
pp. 1121-1124 ◽  
Author(s):  
Alfred C. Lenz
Keyword(s):  
Lower Devonian ◽  
Yukon Territory ◽  
Canadian Cordillera ◽  
Early Devonian ◽  
First Time ◽  
Richardson Mountains ◽  
New Occurrences

Two species of Early Devonian graptolites are described from the Richardson Mountains, northern Yukon Territory; these are ?Pristiograptus sp. and Monograptus fanicus Koren', the latter being reported for the first time from the northern Canadian Cordillera. Associated grapto lites as well as the presence of M. fanicus indicate a Pragian age. The presence of M. fanicus helps fill the zonal gap between the late Lochkovian hercyniens Zone, and probable late Pragian thomasi and yukonensis Zones, and suggests that lower and upper Pragian substage divisions are possibly recognizable in the graptoiite facies.

Nd–Sr isotopic constraints on the interactions of the Intermontane Superterrane with the western edge of North America in the southern Canadian Cordillera

1995 ◽  
Vol 32 (10) ◽  
pp. 1740-1758 ◽  
Author(s):  
Dipak K. Ghosh
Keyword(s):  
North American ◽  
Late Jurassic ◽  
Crustal Contamination ◽  
Late Triassic ◽  
Western Boundary ◽  
Canadian Cordillera ◽  
Isotopic Compositions ◽  
The North ◽  
Tectonic History ◽  
Early Tertiary

Sr and Nd isotopic compositions of the late Paleozoic metavolcanics and Late Triassic to early Tertiary granitoids from four magmatic episodes in the southern Canadian Cordillera from the Kootenay Arc to the Fraser Fault have been used to (i) identify the sources of these rocks, (ii) constrain the compressive tectonic history from Middle Jurassic to Paleocene, and (iii) constrain the western boundary of the basement in this region. The 215–190 Ma old primitive granitoids (εNd = +3.1 to 8.7; 87Sr/86Sr = 0.7028 − 0.7043) of the Late Triassic and Early Jurassic magmatic episode were emplaced in the Paleozoic oceanic crust of Quesnellia (εNd = +2.9 to +9.3) prior to its obduction over the basement. In contrast, during the younger magmatic episodes (Middle–Late Jurassic, Cretaceous, and early Tertiary), the granitoids from western Quesnellia show primitive isotopic compositions, and those from eastern Quesnellia show eastward-increasing crust-contaminated compositions. The contaminated characters of the Middle–Late Jurassic (180–150 Ma) granitoids from eastern Quesnellia (εNd = +2.8 to −9.1; 87Sr/86Sr = 0.7041 − 0.7083) suggest that by 180 Ma, the eastern part of Quesnellia obducted over the North American cratonic basement by an amount of about 100 km (Eocene extension corrected) measured from westward shifts of the Nd and Sr isopleths. The eastward-increasing crustal-contamination patterns in the Cretaceous (120–80 Ma) and the Paleocene igneous rocks also show westward shifts of these isopleths by 20 and 70 km, respectively. Thus, we observe that a total 190 km of obduction took place, this amount is similar to the amount of shortening measured in the Rocky Mountains Fold and Thrust Belt, and the western boundary of the North American basement presently lies at least 25–75 km east of the Fraser Fault.

Geological setting and tectonic significance of Mississippian felsic metavolcanic rocks in the Pelly Mountains, southeastern Yukon Territory

1982 ◽  
Vol 19 (1) ◽  
pp. 8-22 ◽  
Author(s):  
James K. Mortensen
Keyword(s):  
Tectonic Setting ◽  
Volcanic Rocks ◽  
Yukon Territory ◽  
Early Tertiary ◽  
Metavolcanic Rocks ◽  
Extensional Tectonic ◽  
Tectonic Significance ◽  
Show Evidence ◽  
Thrust Sheets ◽  
Local Geology

The central Pelly Mountains in southeastern Yukon Territory consist of imbricate thrust sheets, which have undergone syn- and post-thrusting deformation and metamorphism. The local geology is further complicated by the intrusion of Late Cretaceous batholiths, and by strike-slip faulting related to the Tintina Fault, a major northwest-trending transcurrent fault of latest Cretaceous or early Tertiary age. This faulting disrupts the northeast edge of the study area.Upper Devonian and Mississippian strata are present in at least two of the structural packages, but the Mississippian metavolcanic rocks occur only in the lowermost package. Rb–Sr geochronology indicates a mid-Mississippian age for the igneous suite. The volcanic rocks consist of volcaniclastic material with minor interbedded flows, and were deposited in a submarine environment. Several coeval and cogenetic syenite and trachyte domes and small stocks are the remains of vent areas. Although the volcanic rocks are all highly altered and show evidence of widespread chemical mobility, trace element data indicate that the rocks are metaluminous trachytes, most closely resembling peralkaline volcanics generated in extensional environments. This suggestion of a predominantly extensional tectonic setting in mid-Mississippian time in the Pelly Mountains is consistent with recent tectonic syntheses for the area.

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