scholarly journals U - Pb Geochronology of Cretaceous and Tertiary Plutonic Rocks of the Tagish Lake area, northeastern Coast Mountains, British Columbia

1992 ◽  
Author(s):  
L Currie
Keyword(s):  
British Columbia ◽  
Lake Area ◽  
Coast Mountains ◽  
Plutonic Rocks ◽  
Northeastern Coast

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.

Metamorphic framework and plutonic styles in the Prince Rupert region of the Central Coast Mountains, British Columbia

1970 ◽  
Vol 7 (2) ◽  
pp. 376-405 ◽  
Author(s):  
W. W. Hutchison
Keyword(s):  
British Columbia ◽  
Regional Metamorphism ◽  
Plutonic Rock ◽  
Oscillatory Zoning ◽  
Metamorphic Belt ◽  
Coast Mountains ◽  
Eastern Zone ◽  
Median Zone ◽  
Metamorphic Zone ◽  
Plutonic Rocks

The metamorphic framework in Prince Rupert – Skeena region of the Coast Mountains of British Columbia comprises schist, gneiss, and migmatite displaying progressive regional metamorphism that overlaps the Barrovian and Idahoan Facies Series. Although part of the circum-Pacific metamorphic zone, the Coast Mountain metamorphic belt is apparently not paired. Plutonic rocks, which were probably an integral part of the early metamorphic framework, have apparently been mobilized during metamorphism and continued to move out of their original environment while metamorphism waned, some even deforming the pre-existing fabric.Within the framework, four main plutonic styles have been recognized:1) Autochthonous, migmatitic, plutonic complexes.2) Para-autochthonous, steep-walled (tadpole) plutons.3) Para-autochthonous, tongue-shaped, recumbent plutons.4) Allochthonous, intrusive plutons.Quartz diorite and granodiorite are the most common plutonic rocks. Diorite and quartz monzonite are less common: gabbro and especially granite are rare.In the course of moving from the sites of generation to the zones of emplacement, the plutonic rock became:1) more homogeneous.2) less migmatitic and impoverished in inclusions.3) less foliated.4) more acidic, more biotite-rich.5) a rock containing plagioclase of lower average anorthite content and more complex oscillatory zoned crystals.The complex oscillatory zoning appears in a gross way to reflect the variable history accompanying (pulsative ?) movement during crystallization.Time of emplacement of most of the plutonic rock is not known. The potassium–argon age dates (between 53° N and 55° N) display a consistent pattern, with a westerly zone yielding the oldest dates (84 to 140 m.y.), a median zone, intermediate dates (64 to 79 m.y.) and the eastern zone, youngest dates (chiefly 40 to 50 m.y.). These dates may reflect sequential emplacement from west to east but some evidence also suggests that they may reflect sequential uplift and unroofing from west to east.

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.

DURATION OF GARNET GROWTH AND P-T-T PATHS FROM SM-ND DATING AND ISOCHEMICAL PHASE DIAGRAMS: COAST MOUNTAINS BATHOLITH, BRITISH COLUMBIA, CANADA

2017 ◽  
Author(s):  
Elizabeth M. Bollen ◽  
◽  
Harold H. Stowell ◽  
Margaret E. Rusmore ◽  
Glenn J. Woodsworth
Keyword(s):  
British Columbia ◽  
Phase Diagrams ◽  
Garnet Growth ◽  
Coast Mountains

U-PB GEOCHRONOLOGY AND ZIRCON HF AND O ISOTOPE ANALYSIS OF PLUTONS OF THE SOUTHERN COAST MOUNTAINS BATHOLITH, BRITISH COLUMBIA: INSIGHT INTO EPISODIC MAGMATISM IN CONTINENTAL ARCS

2017 ◽  
Author(s):  
Emily C. Homan ◽  
◽  
M. Robinson Cecil ◽  
George E. Gehrels ◽  
Margaret E. Rusmore ◽  
...  
Keyword(s):  
British Columbia ◽  
Isotope Analysis ◽  
Southern Coast ◽  
Coast Mountains ◽  
Continental Arcs ◽  
O Isotope ◽  
Insight Into
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