Biochronology of selected Bowser Basin strata; tectonic significance

1988 ◽  
Vol 25 (10) ◽  
pp. 1571-1578 ◽  
Author(s):  
I. W. Moffat ◽  
R. M. Bustin ◽  
G. E. Rouse
Keyword(s):  
British Columbia ◽  
Late Jurassic ◽  
Plant Succession ◽  
Fossil Plant ◽  
North Central ◽  
Eastern Margin ◽  
Time Period ◽  
Tectonic Significance ◽  
Age Range ◽  
Recent Evaluation

Recent evaluation and reinterpretation of fossil floral and faunal data more clearly define the ages of strata exposed in the Groundhog Coalfield and the surrounding Bowser Basin of north-central British Columbia. In the Groundhog Coalfield, Bowser Lake Group strata consist of an overall coarsening-upwards cycle divisible into four informal stratigraphic units, which are, from oldest to youngest, the Jackson, Currier, McEvoy, and Devils Claw units. The section has an unconformable relationship with underlying Bajocian Spatsizi marine shales, volcanics, and arenaceous sediments. Marine macrofossils indicate a Callovian to Oxfordian age for the Jackson unit. The fossil plant succession present in the overlying Currier unit indicates Late Jurassic affinities. Recent unpublished palynologic data from lower McEvoy rocks in the northern Groundhog Coalfield suggest a Barremian age. The palynoassemblage present in the lower Devils Claw unit in the central part of the Groundhog Coalfield suggests a late middle Albian age.Rocks of the Sustut Group have an angular unconformable relationship with underlying Bowser Lake Group strata near the eastern margin of the Bowser Basin. The palynoassemblage present in Sustut Group rocks from the southern Sustut Basin suggests a Campanian to Maastrichtian age range, in contrast to a probable late Albian to Campanian age range for the northern Sustut Basin and a middle to late Albian age from Sustut Group outliers present within the northern Bowser Basin. Within the Groundhog Coalfield, Devils Claw strata have a conformable or paraconformable relationship with underlying Bowser Lake Group strata.Regional discrepancy in the age and geometry of the sub-Sustut unconformity is attributed to a time-transgressive unconformity that resulted from cratonward advance of an isostatically induced peripheral bulge. Age and contact relationships suggest that deformation in the Bowser Basin and surrounding Sustut Basin must have spanned the time period that corresponds to a second uplift pulse of the Columbian orogen (Aptian to early Cenomanian) and the uplift pulse related to the Laramide orogen (Campanian to Maastrichtian).

Geochronometry of the Eagle Plutonic Complex and the Coquihalla area, southwestern British Columbia

1992 ◽  
Vol 29 (4) ◽  
pp. 812-829 ◽  
Author(s):  
C. J. Greig ◽  
R. L. Armstrong ◽  
J. E. Harakal ◽  
D. Runkle ◽  
P. van der Heyden
Keyword(s):  
British Columbia ◽  
Late Jurassic ◽  
Middle Eocene ◽  
Timing Constraints ◽  
Early Eocene ◽  
East Side ◽  
Eastern Margin ◽  
Plutonic Complex ◽  
Southwestern Margin

New U–Pb, K–Ar, and Rb–Sr dates from the Eagle Plutonic Complex and adjacent map units place timing constraints on intrusive and deformational events along the southwestern margin of the Intermontane Belt. U–Pb zircon minimum dates for Eagle tonalite and gneiss (148 ± 6, 156 ± 4, and 157 ± 4 Ma) document previously unrecognized Middle to Late Jurassic magmatism and syn-intrusive deformation along the eastern margin of the Eagle Plutonic Complex and the southwestern margin of the Intermontane terrane. Widespread mid-Cretaceous (Albian–Cenomanian) resetting of K–Ar and Rb–Sr isotopic systematics in Jurassic and older rocks is coeval and cogenetic with emplacement of plutons of the Fallslake Plutonic Suite (110.5 ± 2 Ma, U–Pb) which crosscut Jurassic plutons and structures but were themselves ductilely deformed along the Pasayten fault during sinistral, east-side-up, reverse displacement. K–Ar and Rb–Sr cooling dates for the Fallslake Suite of ca. 100 Ma, including dates from mylonites along the Pasayten fault, suggest that uplift, cooling, and unroofing of the Eagle Plutonic Complex occurred in mid-Cretaceous time along the Pasayten fault. Regional geologic evidence suggests that this thermal and unroofing event affected much of the southwest margin of the Intermontane Belt. Initial 87Sr/86Sr ratios and U–Pb geochronometry for the Fallslake Plutonic Suite suggest that it was derived, in part, from preexisting and relatively nonradiogenic Paleozoic to Mesozoic crust. K–Ar dating of several stocks demonstrates widespread Early Eocene plutonism in the Coquihalla area, and dating of the Needle Peak pluton indicates plutonism continued into Middle Eocene time.

Geochronology and tectonics of the northern Wolverine Complex, British Columbia

1979 ◽  
Vol 16 (7) ◽  
pp. 1428-1438 ◽  
Author(s):  
Randall R. Parrish
Keyword(s):  
British Columbia ◽  
Late Jurassic ◽  
Blocking Temperature ◽  
Mountain Area ◽  
North Central ◽  
Geothermal Gradients ◽  
Clastic Rocks ◽  
The North ◽  
Uplift Rates ◽  
Uplift And Erosion

The Wolverine Complex is a metamorphosed and polydeformed sequence of Hadrynian clastic rocks that forms part of the Omineca Crystalline Belt in north-central British Columbia. Twenty-six Rb–Sr and K–Ar dates from an area at the north end of the complex are presented. Rb–Sr muscovite dates are the oldest, 70–166 Ma, and constrain the main metamorphic–deformational event to the Middle to Late Jurassic or earlier. K–Ar dates on muscovite and biotite are highly discordant and the dates of the minerals vary in the order Rb–Sr muscovite > K–Ar muscovite > K–Ar biotite. Many rocks show partial or complete homogenization of the isotopes during an early Tertiary thermal event, which has extensively reset K–Ar dates in part of the complex.The blocking temperatures of the isotopic systems when combined with the isotopic dates, other published dates, and estimated geothermal gradients, allow inference of thermal history and paleo-uplift rates. In the Chase Mountain area where the influence of Eocene resetting is either small or minimal, the rocks had cooled to 220 ± 40 °C by about 80 Ma ago or earlier. During their cooling from metamorphic temperatures of about 500 °C, they cooled at rates between 3 and 10 °C/Ma with an average minimum cooling rate of 4 °C/Ma. Using estimated geothermal gradients, corresponding uplift rates were 0.1–0.3 km/Ma or more.Because cooling of these rocks probably took place dominantly by advection resulting from uplift and erosion, a significant portion of the total uplift of these rocks was complete by the time they reached the biotite blocking temperature, 220 °C, at least 80 Ma ago. The predominantly Late Jurassic to Early Cretaceous uplift of the complex implied by these dates has important implications for regional tectonics and models of evolution for the Omineca Crystalline Belt and adjacent areas.

Jura-Cretaceous (Oxfordian to Cenomanian) stratigraphy of the north-central Bowser Basin, northern British Columbia

1989 ◽  
Vol 26 (5) ◽  
pp. 1001-1012 ◽  
Author(s):  
H. O. Cookenboo ◽  
R. M. Bustin
Keyword(s):  
British Columbia ◽  
Lower Cretaceous ◽  
Middle Jurassic ◽  
Late Jurassic ◽  
Upper Jurassic ◽  
Thick Section ◽  
North Central ◽  
The North

Three new formations of Late Jurassic and Early to mid-Cretaceous age are defined for a 2000 m thick section of Jura-Cretaceous rocks exposed in the north-central Bowser Basin. The Currier Formation (Oxfordian to Kimmeridgian or Tithonian) consists of 350–600 m of interbedded shales, siltstones, sandstones, coals, and carbonates. The McEvoy Formation (Barremian to as young as Albian) consists of 400–800 m of siltstones and shales with minor sandstones, thin coals, limestones, and conglomerates. The Devils Claw Formation (in part mid-Albian to Cenomanian) consists of 300–600 m of strata characterized by thick pebble and cobble conglomerates, with associated coarse sandstones and minor siltstones and shales.Two successive coarsening-upward sequences are identified in the study area. The first begins with Middle Jurassic marine shales of the Jackson unit grading upwards to coarser Upper Jurassic facies of the Currier Formation. The Currier Formation is conformably or unconformably overlain by siltstones and shales of the Lower Cretaceous McEvoy Formation, which forms the base of a second coarsening-upward sequence. Conglomerates appear with increasing frequency in the upper McEvoy and are the dominant lithology of the overlying Devils Claw Formation. The contact between the McEvoy and Devils Claw formations is gradational. The Devils Claw Formation forms the top of the second coarsening-upward sequence.The Currier Formation (Late Jurassic) is equivalent to the upper units of the Bowser Lake Group. The McEvoy and the Devils Claw formations (Barremian to Cenomanian) are coeval with the Skeena Group (Hauterivian? to Cenomanian). A probable unconformity separating the Upper Jurassic Currier Formation from the Lower Cretaceous McEvoy Formation correlates with a hiatus in the southern Bowser Basin and probably represents a regional unconformity.

A nearly complete skeleton of an early juvenile diplodocid (Dinosauria: Sauropoda) from the Lower Morrison Formation (Late Jurassic) of north central Wyoming and its implications for early ontogeny and pneumaticity in sauropods

2007 ◽  
Vol 19 (3) ◽  
pp. 225-253 ◽  
Author(s):  
Daniela Schwarz ◽  
Takehito Ikejiri ◽  
Brent H. Breithaupt ◽  
P. Martin Sander ◽  
Nicole Klein
Keyword(s):  
Late Jurassic ◽  
Early Ontogeny ◽  
Morrison Formation ◽  
North Central ◽  
Early Juvenile

Using perceptual maps to communicate concepts of Sustainable Forest Management – Collaborative research with the Office of the Wet'suwet'en Nation in British Columbia

2005 ◽  
Vol 81 (3) ◽  
pp. 381-386
Author(s):  
S. Denise Allen
Keyword(s):  
British Columbia ◽  
Forest Management ◽  
Collaborative Research ◽  
Sustainable Forest Management ◽  
Software Tool ◽  
Decision Makers ◽  
North Central ◽  
Criteria And Indicators ◽  
Perceptual Maps ◽  
Forest Resources Management

This article discusses collaborative research with the Office of the Wet'suwet'en Nation on their traditional territories in north-central British Columbia, Canada, a forest-dependent region where contemporary and traditional forest resources management regimes overlap. In-depth personal interviews with the hereditary chiefs and concept mapping were used to identify social-ecological linkages in Wet'suwet'en culture to inform the development of culturally sensitive social criteria and indicators of sustainable forest management (SFM) in this region. The preliminary results demonstrate how the CatPac II software tool can be applied to identify key component concepts and linkages in local definitions of SFM, and translate large volumes of (oral) qualitative data into manageable information resources for forest managers and decision-makers. Key words: social criteria and indicators, sustainable forest management, qualitative research, Wet'suwet'en

scholarly journals Maintaining the Uptake of Peritoneal Dialysis During the COVID-19 Pandemic: A Research Letter

2021 ◽  
Vol 8 ◽  
pp. 205435812098626
Author(s):  
Mark Canney ◽  
Lee Er ◽  
John Antonsen ◽  
Michael Copland ◽  
Rajinder Suneet Singh ◽  
...  
Keyword(s):  
British Columbia ◽  
Peritoneal Dialysis ◽  
Confidence Interval ◽  
Clinical Information System ◽  
Clinical Information ◽  
Catheter Insertion ◽  
Peritoneal Dialysis Catheter ◽  
Time Period ◽  
Hospital Patients ◽  
Maintenance Dialysis

Background: Due to inherent challenges in maintaining physical distancing in hemodialysis units, the Canadian Society of Nephrology has recommended peritoneal dialysis as the preferred modality for patients requiring maintenance dialysis during the coronavirus disease 19 (COVID-19) pandemic. However, pursuing peritoneal dialysis is not without risk due to the requirement for in-person contact during catheter insertion and training, and there is a paucity of data regarding the experience of peritoneal dialysis during the early phases of the pandemic. Objective: To examine the incidence and outcomes of peritoneal dialysis between March 17 and June 01, 2020 compared to the same time period in preceding years. Design: Retrospective observational study. Setting: British Columbia, Canada. After the pandemic was declared on March 17, 2020, patients continued to be trained in peritoneal dialysis. In an effort to limit time spent in hospital, patients were preferentially trained in continuous ambulatory peritoneal dialysis, training times were truncated for some patients, and peritoneal dialysis catheters were inserted by a physician at the bedside whenever feasible. Patients: All patients aged >18 years who started chronic maintenance dialysis during the period March 17 to June 01 in the years 2018 to 2020 inclusive. The time period was extended to include the years 2010 to 2020 inclusive to evaluate longer term trends in dialysis incidence. Measurements: A provincial clinical information system was used to capture the date of commencing dialysis, dialysis modality, and complications including peritonitis. Overall uptake of peritoneal dialysis included new starts and transitions to peritoneal dialysis from in-center hemodialysis during the observation period. Methods: The incidence of dialysis during the specified time period, overall and by modality, was calculated per million population using census figures for the population at risk. Patients were followed for a minimum of 30 days from the start of peritoneal dialysis to capture episodes of peritonitis and COVID-19. Results: A total of 211 patients started maintenance dialysis between March 17 and June 01, 2020. The incidence dialysis rate (41.3 per million population) was lower than that expected based on the 10-year trend from 2010 to 2019 inclusive (expected rate 45.7 per million population, 95% confidence interval 41.7 to 50.1). A total of 93 patients started peritoneal dialysis, including 32 patients who transitioned from in-center hemodialysis, contributing to a higher overall uptake of peritoneal dialysis compared to preceding years. The incidence rate for peritoneal dialysis of 18.2 per million population was higher than that expected (16.3 per million population, 95% confidence interval 14.0 to 19.0). Half of patients (48%) underwent a bedside peritoneal dialysis catheter insertion by a physician. During 30 days of follow-up, 2 (2.2%) patients experienced peritonitis and no patients were diagnosed with COVID-19. Limitations: Results are short term and generalizable only to regions with similarly low community rates of transmission of severe acute respiratory syndrome coronavirus 2. Conclusions: These preliminary findings indicate that peritoneal dialysis can be safely started and perhaps expanded as a means of mitigating the anticipated surge in in-center hemodialysis during the COVID-19 pandemic. Important contributors to the uptake of peritoneal dialysis in British Columbia were bedside catheter insertions and expediting transitions from in-center hemodialysis to peritoneal dialysis.

Characterization of Electroencephalographic Findings at an Electrodiagnostic Unit of a Tertiary Hospital, North-central Nigeria

2021 ◽  
Vol 2 (1) ◽  
pp. 49-55
Author(s):  
E U Iwuozo ◽  
J O Enyikwola ◽  
I O Obekpa ◽  
O O Ijachi ◽  
A A Godwin ◽  
...  
Keyword(s):  
Tertiary Hospital ◽  
Seizure Disorder ◽  
Cross Sectional ◽  
North Central ◽  
Younger Age ◽  
High Prevalence ◽  
Diagnosis And Classification ◽  
Age Range

Electroencephalography (EEG) remains an important investigative tool in supporting the diagnosis and classification of various seizure types. We sought to examine and characterize the EEG findings from all patients referred for the procedure. This cross-sectional retrospective study was carried out at an EEG unit in Federal Medical Centre, Makurdi, Benue State, North Central Nigeria from May 2016 to December 2020. Relevant patients' information were extracted and analysed using SPSS version 21. A total of 484 patients were seen over the study period with age range of 1-87 years and median age of 23 years. They comprised of 254 (52.5%) male and 230 (47.5%) female. The psychiatrist and the Physicians/Neurologist referred most of them for EEG, 201 (41.5%) and 124 (25.6%) respectively. The most reported indication for EEG was clinical suspicion of seizure disorder 291 (60.1%), whilst some did not have a clear indication 111 (22.9%). About 417 (86.2%) of our patients had abnormal EEG finding out of which 414 (99.3%) were diagnostic of seizure disorder made up of generalized seizure in 255 (61.6%) and focal seizure in 159 (38.4%). About 237 (48.9%) of them were already on antiepileptic drugs (AEDs) at referral of which 190 (80.2%0 were taking carbamazepine. This study showed a high prevalence of abnormal EEG with most of them diagnostic of seizure disorder especially generalized seizure. They were mostly of younger age group with about half of them already on AEDs at referral, majority of who were sent by the Psychiatrist.

A Lower Jurassic heteroporid bryozoan and associated biota, Turnagain Lake, British Columbia

1981 ◽  
Vol 18 (3) ◽  
pp. 457-468 ◽  
Author(s):  
C. M. Henderson ◽  
D. G. Perry
Keyword(s):  
British Columbia ◽  
North America ◽  
Green Alga ◽  
Marine Environment ◽  
High Energy ◽  
Lower Jurassic ◽  
Early Jurassic ◽  
Associated Fauna ◽  
North Central ◽  
Commensal Relationship

Late Early Jurassic heteroporid bryozoa occur in arenaceous carbonates near Turnagain Lake, north-central British Columbia. The occurrence of Heteropora tipperi n. sp. marks the first documentation of Early Jurassic cyclostome bryozoa in North America. The associated fauna, comprising the ammonite Harpoceras, the foraminifer Reinholdella, and the pelecypod Weyla, establish the age as Early Toarcian. Other associated biota include an endolithic green alga(e), which is demonstrated to have a commensal relationship with H. tipperi n. sp. Sedimentologic and biotic data from the host strata point to a shallow, temperate, high-energy, normal marine environment.

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