scholarly journals Metamorphic rocks in the Tagish Lake area, northern Coast Mountains, British Columbia: a possible link between Stikinia and parts of Yukon - Tanana Terrane

1992 ◽  
Author(s):  
L D Currie
Keyword(s):  
British Columbia ◽  
Metamorphic Rocks ◽  
Northern Coast ◽  
Lake Area ◽  
Coast Mountains

Holocene tephras in lake cores from northern British Columbia, Canada

2008 ◽  
Vol 45 (8) ◽  
pp. 935-947 ◽  
Author(s):  
Thomas R. Lakeman ◽  
John J. Clague ◽  
Brian Menounos ◽  
Gerald D. Osborn ◽  
Britta J.L. Jensen ◽  
...  
Keyword(s):  
British Columbia ◽  
Sediment Cores ◽  
Volcanic Field ◽  
Northern Coast ◽  
Lake Area ◽  
Volcanic Province ◽  
Coast Mountains ◽  
White River ◽  
Subalpine Lakes ◽  
Lake Cores

Sediment cores recovered from alpine and subalpine lakes up to 250 km apart in northern British Columbia contain five previously unrecognized tephras. Two black phonolitic tephras, each 5–10 mm thick, occur within 2–4 cm of each other in basal sediments from seven lakes in the Finlay River – Dease Lake area. The upper and lower Finlay tephras are slightly older than 10 220 – 10 560 cal year B.P. and likely originate from two closely spaced eruptions of one or two large volcanoes in the northern Cordilleran volcanic province. The Finlay tephras occur at the transition between deglacial sediments and organic-rich postglacial mud in the lake cores and, therefore, closely delimit the termination of the Fraser Glaciation in northern British Columbia. Sediments in Bob Quinn Lake, which lies on the east edge of the northern Coast Mountains, contain two black tephras that differ in age and composition from the Finlay tephras. The lower Bob Quinn tephra is 3–4 mm thick, basaltic in composition, and is derived from an eruption in the Iskut River volcanic field about 9400 cal years ago. The upper Bob Quinn tephra is 12 mm thick, trachytic in composition, and probably 7000–8000 cal years old. A fifth tephra occurs as a cryptotephra near the top of two cores from the Finlay River area and is correlated to the east lobe of the White River tephra (ca. 1150 cal year B.P.). Although present throughout southern Yukon, the White River tephra has not previously been documented this far south in British Columbia. The tephras are valuable new isochrons for future paleoenvironmental studies in northern British Columbia.

Nd isotopic characteristics of metamorphic and plutonic rocks of the Coast Mountains near Prince Rupert, British Columbia

1998 ◽  
Vol 35 (5) ◽  
pp. 556-561 ◽  
Author(s):  
P J Patchett ◽  
G E Gehrels ◽  
C E Isachsen
Keyword(s):  
British Columbia ◽  
Volcanic Rocks ◽  
Metamorphic Rocks ◽  
Published Data ◽  
Isotopic Data ◽  
Crustal Component ◽  
Coast Mountains ◽  
Crustal Rocks ◽  
Metasedimentary Rocks ◽  
Plutonic Rocks

Nd isotopic data are presented for a suite of metamorphic and plutonic rocks from a traverse across the Coast Mountains between Terrace and Prince Rupert, British Columbia, and for three contrasting batholiths in the Omineca Belt of southern Yukon. A presumed metamorphic equivalent of Jurassic volcanic rocks of the Stikine terrane gives epsilon Nd = +6, and a number of other metaigneous and metasedimentary rocks in the core of the Coast Mountains give epsilon Nd values from +3 to +7. A single metasedimentary rock approximately 3 km east of the Work Channel shear zone gives a epsilon Nd value of -9. Coast Belt plutons in the traverse yield epsilon Nd from -1 to +2. The Omineca Belt plutons give epsilon Nd from -10 to -17. All results are consistent with published data in demonstrating that (i) juvenile origins for both igneous and metamorphic rocks are common in the Coast Belt; (ii) representatives of a continental-margin sedimentary sequence with Precambrian crustal Nd are tectonically interleaved in the Coast Mountains; (iii) Coast Mountains plutons can be interpreted as derived from a blend of metamorphic rocks like those seen at the surface, or as arc-type melts contaminated with the older crustal component; and (iv) Omineca Belt plutons are dominated by remelted Precambrian crustal rocks.

Late Quaternary glacial and interglacial environments of the Nechako River - Cheslatta Lake area, central British Columbia

2001 ◽  
Vol 38 (4) ◽  
pp. 719-731 ◽  
Author(s):  
A Plouffe ◽  
V M Levson
Keyword(s):  
British Columbia ◽  
Late Quaternary ◽  
Late Glacial ◽  
Lake Area ◽  
Glacial Lakes ◽  
Ice Flow ◽  
Coast Mountains ◽  
Quaternary Stratigraphy ◽  
History Of ◽  
Quaternary History

The Quaternary stratigraphy of the Nechako River – Cheslatta Lake area of central British Columbia is described and interpreted to reconstruct the late Quaternary history of the region. Exposures of glacial and nonglacial sediments deposited prior to the last glaciation (Fraser) are limited to three sites. Pollen assemblages from pre-Fraser nonglacial sediments at two of these sites reveal forested conditions around 39 000 BP. During the advance phase of the Fraser Glaciation, glacial lakes were ponded when trunk glaciers blocked some tributary valleys. Early in the glaciation, the drainage was free in easterly draining valleys. Subsequently, the easterly drainage was blocked either locally by sediments and ice or as a result of impoundment of the Fraser River and its tributaries east of the study area. Ice generally moved east and northeast from accumulation zones in the Coast Mountains. Ice flow was influenced by topography. Major late-glacial lakes developed in the Nechako River valley and the Knewstubb Lake region because potential drainage routes were blocked by ice.

Geothermal Data from the Granduc Area, Northern Coast Mountains of British Columbia

1972 ◽  
Vol 9 (10) ◽  
pp. 1333-1337 ◽  
Author(s):  
W. H. Mathews
Keyword(s):  
Thermal Conductivity ◽  
British Columbia ◽  
Heat Flow ◽  
Thermal Gradient ◽  
Temperature Measurements ◽  
Simplified Model ◽  
Northern Coast ◽  
Rock Glacier ◽  
Coast Mountains

Temperature measurements have been obtained from 80 points along the Granduc haulage tunnel, at depths of as much as 1.5 km below the surface. These fit, within 1 °C, a simplified model assuming, among other things, uniform thermal conductivity of the rocks and a temperature at rock–glacier contacts of 0 °C. For these assumptions a generalized thermal gradient (with effects of topographic irregularity removed) is about 26 mK m−1 (26 °C/km). With the thermal conductivity of a suite of rocks from the tunnel averaging 2.72 ± 12 W m−1K−1 (6.50 ±.28 cal/cm s °C) present heat flow of about 73 mW m−2 (1.74 μcal/cm2 s) can be derived.

scholarly journals Late Cretaceous to Paleocene Tectonometamorphic Evolution of the Blanchard River Assemblage, Southwest Yukon: New Insight into the Terminal Accretion of Insular Terranes in the Northern Cordillera

Lithosphere ◽  
2020 ◽  
Vol 2020 (1) ◽  
Author(s):  
Lianna Vice ◽  
H. Daniel Gibson ◽  
Steve Israel
Keyword(s):  
British Columbia ◽  
Late Cretaceous ◽  
Amphibolite Facies ◽  
Contact Metamorphism ◽  
Northern Coast ◽  
Coast Mountains ◽  
Tectonic Events ◽  
Western Cordillera ◽  
History Of ◽  
Northwestern North America

Abstract The Intermontane-Insular terrane boundary stretches over 2000 kilometers from British Columbia to Alaska in the western Cordillera. Juxtaposed between these terranes is a series of Jura-Cretaceous basinal and arc assemblages that record a complicated and contested tectonic evolution related to the Mesozoic-Paleocene accretionary history of northwestern North America. In southwest Yukon, west-verging thrust faults facilitated structural stacking of the Yukon-Tanana terrane over these basinal assemblages, including the Early Cretaceous Blanchard River assemblage. These previously undated compressional structures are thought to be related to the final collapse of the Jura-Cretaceous basins and the tectonic burial of the Blanchard River assemblage resulting in amphibolite facies metamorphism. New in situ U-Th-Pb monazite ages record at least three tectonic events: (1) the tectonic burial of the Blanchard River assemblage to amphibolite facies conditions between 83 and 76 Ma; (2) peak burial was followed by regional exhumation at ca. 70-68 Ma; and (3) intense heating and ca. 63-61 Ma low-pressure contact metamorphism attributed to the intrusion of the voluminous Ruby Range suite, which is part of the northern Coast Mountains batholith. The tectonometamorphic evolution recorded in the Blanchard River assemblage can be correlated to tectonism within southwest Yukon and along the length of the Insular-Intermontane boundary from western British Columbia through southwestern Yukon and Alaska. In southwest Yukon, these results suggest an asymmetric final collapse of Jura-Cretaceous basins during the Late Cretaceous, which relates to the terminal accretion of the Insular terranes as they moved northward.

The sedimentary record and Neoglacial history of Tide Lake, northwestern British Columbia

1992 ◽  
Vol 29 (11) ◽  
pp. 2383-2396 ◽  
Author(s):  
John J. Clague ◽  
William H. Mathews
Keyword(s):  
Twentieth Century ◽  
British Columbia ◽  
Ice Age ◽  
Second Phase ◽  
Northern Coast ◽  
Coast Mountains ◽  
Fine Sediments ◽  
Early Twentieth Century ◽  
Outburst Floods ◽  
History Of

Tide Lake was the largest glacier-dammed lake in British Columbia before its demise in the early twentieth century. Situated in the northern Coast Mountains, the lake was impounded by Frank Mackie Glacier and its Neoglacial end moraine. A study of Tide Lake has provided information on styles of glaciolacustrine sedimentation and the chronology of the Neoglacial interval.Much of the sediment underlying the floor of Tide Lake was transported by subglacial and proglacial meltwater streams flowing from nearby glaciers. During the last phase of the lake, large subaqueous fans were built in front of Berendon and Frank Mackie glaciers, and deltas formed on the east side of the basin. Rhythmically bedded fine sediments, which cover much of the lake floor but are almost completely lacking on the slopes above, were deposited from underflows originating on deltas and subaqueous fans and by fallout from interflows and overflows.Three major and one minor lake phases are recognized from stratigraphic, geomorphic, radiocarbon, and dendrochronological data: the earliest phase is undated, but older than 3000 BP (1300 B.C.); the second phase has yielded radiocarbon ages of 2600–2700 BP (800–1000 B.C.); a third, minor phase, during which Tide Lake was restricted to the northern part of the basin, began before 1600 BP (A.D. 350–550) and probably ended a few hundred years later; the last phase may have begun as early as 1000 BP (A.D. 1000–1150), peaked in the seventeenth century, and ended in the early twentieth century. During each of the four phases, Tide Lake fluctuated in a complex fashion and at times was empty. The second phase corresponds to a widely recognized middle Neoglacial advance in western North America; the last phase is coincident with the Little Ice Age. Outburst floods from Tide Lake in the nineteenth and early twentieth centuries devastated Bowser River valley as far downstream as Bowser Lake. The last of the floods occurred around A.D. 1930 when the Frank Mackie moraine was breached and the lake emptied for the last time.

Neoglacial history of the Stikine–Iskut area, northern Coast Mountains, British Columbia

1987 ◽  
Vol 24 (7) ◽  
pp. 1294-1301 ◽  
Author(s):  
J. M. Ryder
Keyword(s):  
British Columbia ◽  
Aerial Photograph ◽  
Northern Coast ◽  
Historical Records ◽  
Radiocarbon Dates ◽  
Coast Mountains ◽  
Low Level ◽  
The Past ◽  
History Of ◽  
Late Nineteenth

Information about Neoglacial features was obtained from aerial photograph interpretation, observations during low-level flights, ground checking, and historical records. Terminal moraines at Great, Flood, and Mud glaciers date from the late seventeenth to early eighteenth centuries, and recessional moraines at these glaciers and terminal moraines at glaciers farther east date from the late nineteenth to early twentieth centuries. These late Neoglacial terminal moraines appear, in general, to mark the greatest post-Pleistocene extent of the glaciers. Radiocarbon dates from overridden trees and soil indicate that 500–600 14C years BP glaciers were considerably more extensive than they are at present and were advancing. Preservation of a 3800 14C year old caribou antler in a snowbank that is now rapidly shrinking suggests that climate has been relatively cool and moist for the past four millennia.

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