Glacial Marine Sedimentation and Stratigraphy of the Toby Conglomerate (Upper Proterozoic), Southeastern British Columbia, Northwestern Idaho and Northeastern Washington

1971 ◽  
Vol 8 (7) ◽  
pp. 753-787 ◽  
Author(s):  
K. R. Aalto
Keyword(s):  
British Columbia ◽  
Regional Variation ◽  
Volcanic Rocks ◽  
Sedimentary Rocks ◽  
Ice Age ◽  
Late Precambrian ◽  
Upper Proterozoic ◽  
Marine Sedimentation ◽  
Grain Flow ◽  
New Interpretation

The outcrop of the Toby Conglomerate extends sinuously from southeastern British Columbia to northeastern Washington. It constitutes the basal part of the Windermere System (Upper Proterozoic), unconformably overlies the beveled Upper Purcell System, and conformably underlies either volcanic rocks or clastic Windermere sedimentary rocks of the Horsethief Creek Group and Monk Formation. The Toby Conglomerate consists chiefly of diamictite, which is complexly interstratified with conglomerates, sandstones, and argillites, the latter two containing dispersed megaclasts. Toby Conglomerate thickness ranges markedly from a few to nearly 2000 m. There is a dearth of tractive-current features within Toby sedimentary rocks. The presence of overlying pillow lavas and laminated argillites, turbidites, and grain flow deposits suggest that the basal Windermere System is of sub-aqueous origin. Paleogeographic reconstruction indicates deposition in the sea west of the orogenic landmass, Montania, peninsular to the Canadian Shield.Texture, composition, stratigraphie associations of Toby sedimentary rocks, and a lack of consistent regional variation suggest that the Toby Conglomerate was deposited by glacial marine sedimentation. Montania was overridden by ice traveling westward from the shield prior to Toby deposition. The basal Horsethief Creek Group and Monk Formation were produced largely by postglacial mass flow of slumped tills and deltaic deposits. This represents a new interpretation of the genesis of the Toby Conglomerate, one which accords with worldwide evidences of a Late Precambrian ice age.

Crustal velocity structure of the southern Nechako basin, British Columbia, from wide-angle seismic traveltime inversion1This article is one of a series of papers published in this Special Issue on the theme of New insights in Cordilleran Intermontane geoscience: reducing exploration risk in the mountain pine beetle-affected area, British Columbia.

2011 ◽  
Vol 48 (6) ◽  
pp. 1050-1063 ◽  
Author(s):  
A.L. Stephenson ◽  
G.D. Spence ◽  
K. Wang ◽  
J.A. Hole ◽  
K.C. Miller ◽  
...  
Keyword(s):  
British Columbia ◽  
Mountain Pine Beetle ◽  
Velocity Structure ◽  
Volcanic Rocks ◽  
Sedimentary Rocks ◽  
Velocity Model ◽  
Seismic Profile ◽  
Wide Angle ◽  
Seismic Velocities ◽  
Coast Mountains

In the BATHOLITHSonland seismic project, a refraction – wide-angle reflection survey was shot in 2009 across the Coast Mountains and Interior Plateau of central British Columbia. Part of the seismic profile crossed the Nechako Basin, a Jurassic–Cretaceous basin with potential for hydrocarbons within sedimentary strata that underlies widespread volcanic rocks. Along this 205 km-long line segment, eight large explosive shots were fired into 980 seismometers. Forward and inverse modelling of the traveltime data were conducted with two independent methods: ray-tracing based modelling of first and secondary arrivals, and a higher resolution wavefront-based first-arrival seismic tomography. Material with velocities less than 5.0 km/s is interpreted as sedimentary rocks of the Nechako Basin, while velocities from 5.0–6.0 km/s may correspond to interlayered sedimentary and volcanic rocks. The greatest thickness of sedimentary rocks in the basin is found in the central 110 km of the profile. Two sub-basins were identified in this region, with widths of 20–50 km and maximum sedimentary depths of 2.5 and 3.3 km. Such features are well-defined in the velocity model, since resolution tests indicate that features with widths greater than ∼13 km are reliable. Beneath the sedimentary rocks, seismic velocities increase more slowly with depth — from 6.0 km/s just below the basin to 6.3 km/s at ∼17 km in depth, and then to 6.8–7.0 km/s at the base of the crust. The Moho is found at a depth of 33.5–35 km beneath the profile, and mantle velocities are high at 8.05–8.10 km/s.

Provenance of Paleozoic sedimentary rocks in the Canadian Cordilleran miogeocline: a Nd isotopic study

1997 ◽  
Vol 34 (12) ◽  
pp. 1603-1618 ◽  
Author(s):  
Carmala N. Garzione ◽  
P. Jonathan Patchett ◽  
Gerald M. Ross ◽  
JoAnne Nelson
Keyword(s):  
British Columbia ◽  
Northwest Territories ◽  
Middle Devonian ◽  
Volcanic Rocks ◽  
Sedimentary Rocks ◽  
Canadian Shield ◽  
Isotopic Study ◽  
Middle Ordovician ◽  
Southern Alberta ◽  
T Values

Nd isotopes and trace elements in sedimentary rocks of the Yukon, the Northwest Territories, and northern British Columbia are used to examine the source of sediments in the Canadian Cordilleran miogeocline. Previous Nd isotope studies in southern Alberta demonstrated that strata of Neoproterozoic to Late Ordovician age were derived from Archean and Proterozoic Canadian Shield sources, whereas by the Late Devonian, a shift of 6 εNd units to younger crustal sources (εNd (T) = −6 to −9) had occurred. In this study, we found that the shift to younger crustal Nd isotopic signatures in the Yukon and Northwest Territories occurred much earlier than in southern Alberta. Cambrian and older strata have εNd(T) values of −10.0 to −21.1, consistent with derivation from Canadian Shield sources. Lower Ordovician through Permian strata in the Yukon and Northwest Territories, including the Innuitian-derived Imperial Assemblage, have εNd(T) values of −5 to −11.4. In northern British Columbia, the shift to a younger source reflects a wider range of εNd(T) values, from -−8.7 to −14.6 in Middle Ordovician through Middle Devonian strata, suggesting continued input from Canadian Shield sources. By the Middle Devonian, a complete shift to younger crustal signatures (εNd(T) = −5.9 to −10.5) had occurred in northern British Columbia. Several sources for the more juvenile sediments include (1) a mixture of locally erupted volcanic rocks with Canadian Shield sources, (2) a Grenville source, and (3) an Innuitian source. We propose that Ordovician to Lower Devonian strata were derived from a mixture of locally erupted, juvenile volcanics and pre-Cambrian Canadian Shield sources, and post-Middle Devonian strata were sourced from the Innuitian orogen in the Canadian Arctic.

Distribution of Paleogene and Cretaceous rocks around the Nazko River belt of central British Columbia from 3-D long-offset first-arrival seismic tomography

2014 ◽  
Vol 51 (4) ◽  
pp. 358-372 ◽  
Author(s):  
Draga Talinga ◽  
Andrew J. Calvert
Keyword(s):  
British Columbia ◽  
Seismic Velocity ◽  
Volcanic Rocks ◽  
Sedimentary Rocks ◽  
Three Dimensional ◽  
Gravity Anomalies ◽  
Hydrocarbon Exploration ◽  
P Wave ◽  
Velocity Models ◽  
First Arrival

Across the Nechako–Chilcotin plateau of British Columbia, the distribution of Cretaceous sedimentary rocks, which are considered prospective for hydrocarbon exploration, is poorly known due to the surface cover of glacial deposits and Tertiary volcanic rocks. To constrain the subsurface distribution of these Cretaceous rocks, in 2008 Geoscience BC acquired seven long, up to 14.4 km, offset vibroseis seismic reflection lines across a north-northwest-trending belt of exhumed sedimentary rocks inferred to be part of the Taylor Creek Group. P-wave velocity models, which are consistent with sonic logs from nearby wells, have been estimated using three-dimensional first-arrival tomography to depths ranging from 1 to 4 km. Igneous basement can be identified on most lines using the 5.5 km/s isovelocity contour, which locates the top of the basement to an accuracy of ∼400 m where its depth is known in exploration wells. There is no general distinction on the basis of seismic velocity between Cretaceous sedimentary and Paleocene–Eocene volcanic–volcaniclastic rocks, both of which appear to be characterized in the tomographic models by velocities of 3.0–5.0 km/s. The geometry of the igneous basement inferred from the velocity models identifies north-trending basins and ridges, which correlate with exposed rocks of the Jurassic Hazelton Group. Identified Cretaceous sedimentary rocks occur beneath less negative Bouguer gravity anomalies, but the original distribution of these rocks has been disrupted by later Tertiary extension that created north-trending basins associated with the most negative gravity anomalies. We suggest that Cretaceous sedimentary rocks, if deposited, could be preserved within these basins if the rocks had not been eroded prior to Tertiary extension.

Mississippian volcanic assemblage conformably overlying Cordilleran miogeoclinal strata, Turnagain River area, northern British Columbia, is not part of an accreted terrane

2005 ◽  
Vol 42 (8) ◽  
pp. 1449-1465 ◽  
Author(s):  
Philippe Erdmer ◽  
Mitchell G Mihalynuk ◽  
Hubert Gabrielse ◽  
Larry M Heaman ◽  
Robert A Creaser
Keyword(s):  
British Columbia ◽  
Volcanic Rocks ◽  
Sedimentary Rocks ◽  
Lower Paleozoic ◽  
Magmatic Arc ◽  
Structural Relationships ◽  
Geochemical Study ◽  
Tectonic Contact ◽  
Back Arc ◽  
T Values

A Paleozoic volcanic assemblage exposed in northern British Columbia, near the Turnagain River, previously considered to be part of an accreted terrane, was reported to be in depositional contact with a part of the Cordilleran miogeocline. This paper presents an integrated field, U–Pb geochronology, Sm–Nd isotopic, and geochemical study across the basal contact of the volcanic assemblage. Strongly evolved εNd(T) values, between –13 and –21, from samples of lower Paleozoic sedimentary rocks exposed below the volcanic rocks, and correlated with Atan – Kechika – Road River – Earn strata of the miogeocline farther east, support a North American miogeoclinal affinity, consistent with previously established regional stratigraphic and structural relationships. Nd isotopic data from the volcanic assemblage contrast significantly with data from the sedimentary rocks and record a mantle source (εNd(T) values between +4.0 and +7.0), consistent with a magmatic arc or back arc; negative Nb anomalies are similarly compatible with either arc- or back-arc-related magmatism. A concordant 339.7 ± 0.6 Ma U–Pb zircon date was obtained from the volcanic assemblage. The mixed gradational contact between the miogeoclinal and volcanic rocks is marked by interlayering of finely laminated grey and green phyllites on the scale of centimetres, with no evidence of a tectonic contact. Bedding at the contact is folded into tight outcrop-scale folds that are intruded by an Early Jurassic (187.5 ± 2.9 Ma) granodiorite. On the basis of all available evidence, the contact is interpreted as a facies transition. The Mississippian volcanic assemblage may link the miogeocline with the early development of an Angayucham – Slide Mountain basin.

Eocene sedimentation and volcanism in the Fig Lake Graben, southwestern British Columbia

1989 ◽  
Vol 26 (7) ◽  
pp. 1368-1373 ◽  
Author(s):  
Derek J. Thorkelson
Keyword(s):  
British Columbia ◽  
Shear Zone ◽  
Volcanic Rocks ◽  
Sedimentary Rocks ◽  
Fault System ◽  
Normal Faulting ◽  
Pull Apart Basin ◽  
Fault Block

The Fig Lake Graben is a narrow, complex Eocene basin that developed along part of the Coldwater fault system in southwestern British Columbia. Its origin as a pull-apart basin is probably related to dextral wrench faulting along the Fraser Fault and low-angle normal faulting of the Okanagan shear zone. Within the graben are Kamloops Group volcanic and sedimentary rocks, the thickness of which implies that one fault block has been downthrown at least 4.5 km. Geochemical interpretation of previously published analyses of Kamloops Group volcanic rocks indicates that magma production was genetically related to both extension and subduction.

Geological and geochemical evidence for variable magmatism and tectonics in the southern Canadian Cordillera: Paleozoic to Jurassic suites, Greenwood, southern British Columbia

2001 ◽  
Vol 38 (1) ◽  
pp. 75-90 ◽  
Author(s):  
J Dostal ◽  
B N Church ◽  
T Hoy
Keyword(s):  
British Columbia ◽  
Middle Triassic ◽  
Volcanic Rocks ◽  
Sedimentary Rocks ◽  
Deep Ocean ◽  
Island Arc ◽  
Canadian Cordillera ◽  
South Central ◽  
Upper Paleozoic ◽  
Paleozoic Rocks

The Paleozoic and early Mesozoic rocks of the Greenwood mining camp in southern British Columbia are a part of the Quesnel terrane in the eastern part of the Intermontane Belt of the Canadian Cordillera. Upper Paleozoic rocks include the Knob Hill Group composed of oceanic tholeiitic basalts (with (La/Yb)n [Formula: see text] 0.4–1.2), associated with deep ocean sedimentary rocks and serpentinites; the Attwood Group that comprises island-arc tholeiites (with (La/Yb)n [Formula: see text] 1–4 and positive εNd values), clastic sedimentary rocks and limestones; and a unit of oceanic gabbros with (La/Yb)n < 0.5. These lithologically defined units occur as tectonically emplaced slivers of oceanic crust probably produced during the closure of the Slide Mountain basin during the Permian. They are unconformably overlain by Middle Triassic calc-alkaline volcanic and sedimentary rocks of the Brooklyn Group. The Brooklyn Group volcanic rocks have characteristics of mature island-arc rocks, including (La/Yb)n [Formula: see text] 2.5–4.5 and positive εNd values. The Paleozoic rocks are crosscut by a 200 million years old granodioritic intrusion containing zircon with an Early Proterozoic inheritance age (~2.4 Ga). By inference, southern Quesnellia may have been well offshore from the ancestral North American margin in the Mississippian, in close proximity to the margin by the Middle Triassic, and contiguous with it by the Early Jurassic. It is suggested that the complex tectonic history of extension and contraction of the southern Canadian Cordillera during the post Middle Jurassic can be extended in south-central British Columbia as far back as the upper Paleozoic.

The petrology of the Rossland volcanic rocks, southern British Columbia

1982 ◽  
Vol 93 (7) ◽  
pp. 585 ◽  
Author(s):  
B. BEDDOE-STEPHENS
Keyword(s):  
British Columbia ◽  
Volcanic Rocks

PETROGRAPHIC AND GEOCHEMICAL CHARACTERIZATION OF EOCENE VOLCANIC ROCKS, BRITISH COLUMBIA, AND THEIR APPLICATION TO ARCHAEOLOGICAL TOOLSTONE SOURCING

2017 ◽  
Author(s):  
Lindsay Buff ◽  
◽  
David G. Bailey ◽  
Nathan Goodale ◽  
Heather Kendall ◽  
...  
Keyword(s):  
British Columbia ◽  
Volcanic Rocks ◽  
Geochemical Characterization

Bridge River tephra: revised distribution and significance for detecting old carbon errors in radiocarbon dates of limnic sediments in southern British Columbia

1980 ◽  
Vol 17 (11) ◽  
pp. 1454-1461 ◽  
Author(s):  
Rolf W. Mathewes ◽  
John A. Westgate
Keyword(s):  
British Columbia ◽  
Sedimentary Rocks ◽  
Lacustrine Sediments ◽  
Igneous Rocks ◽  
The South ◽  
Radiocarbon Dates ◽  
Carbon Contamination ◽  
Horseshoe Lake ◽  
Tephra Beds

Ash-grade Bridge River tephra, identified as such on the basis of shard habit, modal mineralogy, and composition of ilmenite, occurs in sedimentary cores from three lakes located to the south of the previously documented plume and necessitates a significant enlargement of the fallout area of that tephra in southwestern British Columbia.These new, more southerly occurrences are probably equivalent to the ~2350 year old Bridge River tephra, although it can be argued from the evidence at hand that the 14C dates and biotite-rich nature support relationship to a slightly earlier Bridge River event.Large differences exist in the 14C age of sediments immediately adjacent to the Bridge River tephra at these three lake sites; maximum ages of 3950 ± 170 years BP (GX-5549) and 3750 ± 210 years BP (I-10041) were obtained at Phair and Fishblue lakes, respectively, whereas the corresponding age at Horseshoe Lake is only 2685 ± 180 years BP (GX-5757). The two older dates are considered to be significantly affected by old carbon contamination for the bedrock locally consists of calcareous sedimentary rocks and the lacustrine sediments are very calcareous. The 14C date from Horseshoe Lake, which occurs in an area of igneous rocks, appears to be only slightly too old relative to the ~2350 year old Bridge River tephra.Well-dated tephra beds, therefore, can be very useful in assessing the magnitude of old carbon errors associated with radiocarbon dates based on limnic sediments. Calcareous gyttja deposits beneath Bridge River tephra within the study area exhibit old carbon errors of the order of 1350–1550 years.

Petrologic variations in quaternary volcanic rocks, British Columbia, and the nature of the underlying upper mantle

1982 ◽  
Vol 79 (2) ◽  
pp. 201-218 ◽  
Author(s):  
J. Nicholls ◽  
M. Z. Stout ◽  
D. W. Fiesinger
Keyword(s):  
British Columbia ◽  
Upper Mantle ◽  
Volcanic Rocks
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