Depositional systems and seismic stratigraphy of a Quaternary basin: north Okanagan Valley, British Columbia

1996 ◽  
Vol 33 (6) ◽  
pp. 917-927 ◽  
Author(s):  
S. Vanderburgh ◽  
M. C. Roberts
Keyword(s):  
British Columbia ◽  
Systems Approach ◽  
Alluvial Fan ◽  
Seismic Profiles ◽  
The North ◽  
South Central ◽  
Depositional Systems ◽  
Late Wisconsinan ◽  
Okanagan Valley ◽  
Basin Fill

Seismic and core data from north Okanagan Valley, a deep (~700 m of fill), elongate (~3 km wide by 45 km long) basin located in the Cordillera of south-central British Columbia, reveal a thick sequence of fine and coarse elastics. The architecture of the basin fill was delineated using 16 km of high-resolution, reflection seismic profiles, and 30 lithologic logs. Using a depositional systems approach, four systems were identified: subglacial fluvial, glaciolacustrine, alluvial fan, and channel. The subglacial fluvial system consists of a basal suite of compact, stratified to poorly stratified coarse clastics deposited beneath glacial ice under high hydrostatic pressure. Older sediments were almost completely excavated from the basin fill during periods of maximum subglacial flow during Late Wisconsinan glaciation. One of the outcomes of this study is that it lends support to the notion that Late Wisconsinan glaciers were capable of almost totally eroding older Pleistocene basin deposits while depositing thick sequences of subglacial fluvial sediments. During deglaciation, the basin was occupied by a lake in which laminated silt and clay were deposited (glaciolacustrine system). The wedge-shaped alluvial fan system interfingers with the finer clastics of the basin fill. Incised into the upper part of the basin fill are channel sediments forming the channel depositional system. Two stages in the evolution of the north Okanagan basin were identified: in the first stage (~10 ka), lake sediments were rapidly accumulating coeval with the formation of alluvial fans and fan deltas; the second stage shows the present-day architecture of the basin fill.

K–Ar and Fission Track Geochronometry of an Eocene Thermal Event in the Kettle River (West Half) Map Area, Southern British Columbia

1975 ◽  
Vol 12 (5) ◽  
pp. 836-843 ◽  
Author(s):  
G. A. Medford
Keyword(s):  
British Columbia ◽  
Abrupt Change ◽  
Fission Track ◽  
Apatite Fission Track ◽  
Thermal Event ◽  
South Central ◽  
Early Tertiary ◽  
Okanagan Valley

The Okanagan and Similkameen plutonic complexes west of the Okanagan Valley of south-central British Columbia yield K–Ar dates that range from 185 to 133 m.y. East of the Okanagan Valley Shuswap gneisses into which the plutonics intrude, and which may be as old as pre-midCarboniferous in age yield K–Ar dates between 59.9 and 47.4 m.y. This abrupt change, which approximately coincides with the Okanagan Valley, is a consequence of an intense thermal event in the early Tertiary which has reset K–Ar dates in the gneisses at shallow depths. Comparison of K–Ar, sphene and apatite fission track dates demonstrates that the heating affected the plutons west of the Okanagan Valley and that cooling of the Shuswap gneisses occurred at a rate in excess of 25 °C. per million years. The scatter observed in the older K–Ar dates of the plutonic complexes could be caused by post-emplacement heating with variable partial argon loss rather than by separate magmatic events. Thus, only the oldesl K–Ar dates obtained from the plutons may be significant as minimum ages for emplacement.

The tephra stratigraphy of two lakes in south-central British Columbia, Canada and its implications for mid-late Holocene volcanic activity at Glacier Peak and Mount St. Helens, Washington, USA

2004 ◽  
Vol 41 (12) ◽  
pp. 1401-1410 ◽  
Author(s):  
Franklin F Foit Jr. ◽  
Daniel G Gavin ◽  
Feng Sheng Hu
Keyword(s):  
British Columbia ◽  
Late Holocene ◽  
Glass Composition ◽  
Apparent Absence ◽  
The North ◽  
South Central ◽  
Tephra Layers ◽  
Tephra Stratigraphy ◽  
Eruptive Period ◽  
Mount St Helens

Several mid-late Holocene Glacier Peak tephras along with Mazama and Mount St. Helens Wn and P tephras were found in cores from Cooley and Rockslide lakes in southeastern British Columbia, ∼300 km northeast of Glacier Peak. The sediments in Cooley Lake host the late Holocene Glacier Peak A tephra (2010 calibrated (cal) years BP), four separate Glacier Peak Dusty Creek (GPDC) tephras (5780–5830 cal years BP), and a Glacier Peak set D tephra (6060 cal years BP). This is the first report of Glacier Peak A and D tephras in British Columbia. The A tephra has been correlated on the basis of glass composition and age to a late Holocene Glacier Peak tephra in the sediments of Big Twin Lake, 75 km northeast of Glacier Peak. The glasses in the four GPDC tephra layers from Cooley Lake are compositionally indistinguishable from those in Mount Barr Cirque and Frozen lakes in southwestern British Columbia. The layers likely represent four eruptions taking place over 50 years. Although set D tephra has not been correlated to a known proximal or distal deposit, its glass bears the Glacier Peak glass compositional signature and its interpolated age corresponds to the initiation of the set D eruptive period. The presence of GPDC tephra in lake sediments across southern British Columbia suggests a broad plume trajectory to the north and northeast, whereas the apparent absence of the A and D tephras in all but Cooley Lake suggest plumes with a northeasterly direction.

The Stratigraphy and Morphology of Para-glacial Alluvial Fans in South-central British Columbia

1971 ◽  
Vol 8 (2) ◽  
pp. 279-298 ◽  
Author(s):  
J. M. Ryder
Keyword(s):  
British Columbia ◽  
Volcanic Ash ◽  
Alluvial Fan ◽  
Alluvial Fans ◽  
River Terraces ◽  
South Central ◽  
Multi Level ◽  
Local Base

Alluvial fan construction within the interior valleys of southern British Columbia was dependent upon temporary conditions resulting from deglaciation. Glacial drift was reworked by streams and mudflows to form fans whose composition is dependent upon the nature of the drift supply and the hydrologic character of the parent basin.Stratigraphic evidence suggests that fan building commenced soon after valley floors became ice-free, continued during post-glacial aggradation by major rivers and for some time after wards. Most recently, fans were built upon degradational river terraces. Mazama volcanic ash within fans indicates that their construction continued until after 6600 years B.P. After deposition ceased many fans were dissected either as local base-levels were lowered under the control of degrading major rivers or by fan-head trenching initiated as the debris supply declined. Where fan building persisted during degradation, multi-level fans were constructed.

Age and Correlation of the Kobau Group, Mount Kobau, British Columbia

1973 ◽  
Vol 10 (10) ◽  
pp. 1508-1518 ◽  
Author(s):  
Andrew V. Okulitch
Keyword(s):  
British Columbia ◽  
Volcanic Rocks ◽  
Metamorphic Rocks ◽  
Low Grade ◽  
South Central ◽  
Shuswap Metamorphic Complex ◽  
Basic Volcanic ◽  
Devonian Age ◽  
Tertiary Period ◽  
Okanagan Valley

The Kobau Group, found in south-central British Columbia, consists of highly deformed, low-grade metamorphic rocks derived from a succession of sedimentary and basic volcanic rocks of pre-Cretaceous, likely post-Devonian age. Deformation began in Carboniferous times and recurred with decreasing intensity up to the Tertiary Period. Possible correlative successions are found surrounding Mount Kobau. These include possibly late Paleozoic formations west and northwest of Mount Kobau, the Carboniferous to Permian Anarchist Group found south of the 49th parallel and east of the Okanagan Valley, the pre-Upper Triassic, possibly Mississippian Chapperon Group west of Vernon, and parts of the Shuswap Metamorphic Complex east of the Okanagan Valley. Prior to deposition of the Kobau Group, part of the Shuswap Complex was subjected to deformation, presumably in mid-Paleozoic time.

scholarly journals How much does the host matter to the parasitoid? Distribution of Eurytoma (Hymenoptera, Chalcidoidea) species amongst two locally co-occurring gall-inducing hosts in the genus Diplolepis (Hymenoptera, Cynipidae)

2020 ◽  
Vol 152 (6) ◽  
pp. 815-822
Author(s):  
Jamie M. MacEwen ◽  
Nathan G. Earley ◽  
Robert G. Lalonde
Keyword(s):  
United States ◽  
British Columbia ◽  
Cytochrome B ◽  
Host Plants ◽  
Growing Season ◽  
Sampling Location ◽  
The North ◽  
Gall Wasps ◽  
North End ◽  
Okanagan Valley

AbstractGall wasps in the cynipid genus Diplolepis Geoffroy (Hymenoptera: Cynipidae) attack various species of native and introduced roses in Canada. Although gall forms are diverse, gall wasps are parasitised by highly concordant complexes of parasitoids and inquilines. Many species of gall wasps attack the same host plants and develop over the same periods in the season, suggesting that opportunistic parasitoids may be exploiting a range of hosts rather than specialising. We sampled larvae of Eurytoma Illiger (Hymenoptera: Cynipidae) from galls of D. variabilis (Bassett) and D. rosaefolii (Cockerell), gall inducers that develop fairly synchronously late in the growing season on leaves of Rosa woodsii Lindl. (Rosaceae) in the Okanagan Valley of central British Columbia, Canada. Galls were sampled at five different sites along a gradient from the north end of the valley to the Canada–United States border, a distance of 100 km. We extracted DNA, then amplified and sequenced the cytochrome b segment for each Eurytoma larva. We identified two well-supported clades that were differentiated by neither sampling location nor host. Instead, at least two species of Eurytoma, E. imminuta Bugbee and E. longavena Bugbee, exist at these localities, and both exploit at least two of the Diplolepis hosts found at these sites.

scholarly journals Characterization of western spruce budworm outbreak regions in the British Columbia Interior

2018 ◽  
Vol 48 (7) ◽  
pp. 783-802 ◽  
Author(s):  
Lorraine E. Maclauchlan ◽  
Lori D. Daniels ◽  
Janice C. Hodge ◽  
Julie E. Brooks
Keyword(s):  
British Columbia ◽  
Spruce Budworm ◽  
Growth Suppression ◽  
Douglas Fir ◽  
Western North America ◽  
Western Spruce Budworm ◽  
The North ◽  
South Central ◽  
Ecosystem Classification

The western spruce budworm (WSB; Choristoneura freemani Razowski) shapes Douglas-fir (Pseudotsuga menziesii (Mirb.) Franco) forests throughout western North America with periodic, severe landscape-level defoliation events. The largest and most continuous recorded defoliation occurred in the 2000s, largely centered in the Williams Lake and 100 Mile House WSB outbreak regions, peaking in 2007 at 847 000 ha defoliated in British Columbia (B.C.). Unique WSB outbreak regions in south-central B.C. are described using biogeoclimatic ecosystem classification, geography, 106 years of documented defoliation, and 46 stand-level Douglas-fir host tree-ring chronologies. Since the 1980s, recorded defoliation in B.C. has shifted from coastal ecosystems and become a dominant disturbance in drier, colder, interior Douglas-fir ecosystems. Defoliation records demarcate four outbreaks from 1950–2012 and up to three growth suppression events from 1937–2012. Outbreak duration was shorter in the north and far south of B.C., with recovery periods (no trees showing growth suppression) shorter over all WSB outbreak regions in the 2000s, suggesting that trees may be increasingly susceptible to each successive defoliation event. Knowing the regional outbreak periodicity may facilitate early detection of incipient WSB populations, which is critical for management as many of our low-elevation Douglas-fir forests become more stressed with changing and unpredictable climate regimes.

Paleomagnetism of the Triassic Guichon Batholith and Rotation in the Interior Plateau, British Columbia

1971 ◽  
Vol 8 (11) ◽  
pp. 1388-1396 ◽  
Author(s):  
D. T. A. Symons
Keyword(s):  
British Columbia ◽  
Pole Position ◽  
Upper Triassic ◽  
Late Triassic ◽  
Ratio Analysis ◽  
Tectonic Block ◽  
Clockwise Rotation ◽  
The North ◽  
South Central ◽  
Intrusive Rocks

The Guichon Batholith, located near the south end of the Interior Plateau in south–central British Columbia, is composed of unmetamorphosed massive felsic intrusive rocks in several distinct phases (Northcote 1969). Stratigraphic and radiometric evidence indicate that the batholith was emplaced during the Late Triassic (198 ± 8 m.y.) and unroofed by Early Jurassic. Analysis of the remanence of 92 cores (184 specimens) from 19 representative sites led to the isolation of a stable primary remanent magnetism at 15 sites after alternating-field demagnetization. Variance ratio analysis of the remanence directions indicates that the phases cannot be distinguished by the paleomagnetic method. This supports the evidence from contact relationships and K–Ar isotopic dating of biotites that the phases cooled nearly contemporaneously. The pole position determined for the Guichon Batholith (12.9° E, 65.6° N) is discordant with other Upper Triassic pole positions determined for North American formations. The discordance may be explained by a clockwise rotation 40° ± 10° of the batholith and surrounding rocks in the southern end of the Interior Plateau, with most of the Plateau to the north acting as a stable non-rotated tectonic block. Other evidence is cited which is consistent with this hypothesis.

scholarly journals Stratigraphy and depositional environments of basin-fill sediments in southern Kathmandu Valley, Central Nepal

1970 ◽  
Vol 11 ◽  
pp. 61-70
Author(s):  
Mukunda Raj Paudel ◽  
Harutaka Sakai
Keyword(s):  
Sedimentary Environment ◽  
Depositional Environments ◽  
Alluvial Fan ◽  
Sediment Distribution ◽  
The North ◽  
Central Nepal ◽  
Southern Margin ◽  
Initial Stage ◽  
Lacustrine Facies ◽  
Basin Fill

Quatenary fluvio-lacustrine basin-fill sediments in the southern part of the Kathmandu Basin was studied in order to clearify the stratigraphy and reconstruct the sedimentary environment during the initial stage of the Paleo-Kathmandu Lake. Six stratigraphic units; Tarebhir, Lukundol, Itaiti, Kalimati, Sunakothi Formations and Terrace gravel deposits, have been described based on field observation of lithology and sediment distribution. The Tarebhir Formation is the basal unit which is overlained by alluvial fan of the Itaiti Formation in the southern part and by the marginal lacustrine deposit of the Lukundol Formation towards the northern part. Further 3 km toward the north from the basin margin at Jorkhu the the Lukundol Formation is overlain by the open lacustrine facies of the Kalimati Formation. At the same locality the latter is overlain by fluvio-lacustrine facies of the Sunakothi Formation. Moreover, the Terrace gravel deposits erosionally cover the Sunakothi Formation. The Kalimati Formation thickens northward, while the Sunakothi Formation thickens between the central and southern part of the basin. The study shows that the Sunakothi Formation is of fluvio-lacustrine (fluvial, deltaic and shallow lacustrine) origin and extends continuously from the southern margin (~1400m amsl) to the central part (~1300m amsl) of the basin. It also indicates that sediments of this formation were deposited at the time of lake level rise and fall. Thick gravel sequence in the southern margin represents the alluvial fan before the origin (before 1 Ma) of the Paleo-Kathmandu Lake, while thick gravel sequence situated above the Sunakothi Formation is the Terrace gravel deposits of the late Pleistocene age (14C method), deposited during and after the shrinkage of the Paleo-Kathmandu Lake from south to north.   doi: 10.3126/bdg.v11i0.1544 Bulletin of the Department of Geology, Tribhuvan University, Kathmandu, Nepal, Vol. 11, 2008, pp. 61-70

Sign in / Sign up

Export Citation Format

Share Document