The geometry of folded and thrusted rocks in the Rocky Mountain Foothills near Grande Cache, Alberta

1985 ◽  
Vol 22 (11) ◽  
pp. 1711-1719 ◽  
Author(s):  
Willem Langenberg
Keyword(s):  
Rocky Mountains ◽  
Lower Cretaceous ◽  
Rocky Mountain ◽  
Thrust Fault ◽  
Southeastern Part ◽  
Apical Angle ◽  
Clastic Rocks ◽  
Stratigraphic Section ◽  
Fault Displacement

Lower Cretaceous clastic rocks make up the Inner Foothills of the Rocky Mountains along the Smoky River near Grande Cache, Alberta. Shortening of these rocks is accomplished by folding and thrusting and averages 33% over the area studied.Folds in the area are of the chevron variety. They are caused by shortening of a multilayered sequence of alternating competent and incompetent strata, where the thickness of the competent layers is fairly constant. The folds are generally cylindrical and maintain their shapes over distances of up to 2 km along trend. However, at their tapering ends they are conical.The majority of the faults are southwest-dipping thrusts, displaying ramps that cut up stratigraphic section and flats that are parallel to bedding. The best exposed fault in the area is the Mason Thrust. Displacements along this fault increase from 150 m in the northwest to 1500 m in the southeastern part of the area. A prominent anticline below the Mason Thrust diminishes gradually towards the southeast. A conical fold with a half apical angle of 7° describes this geometry. Shortening by this fold decreases from about 30% in the northwest to 10% in the southeastern part of the area. This indicates that a decrease in shortening by folding is compensated by an increase in thrust fault displacement. It is an example of fault-to-fold displacement transfer.

Mitbringsel aus den Ferien

Praxis ◽  
2005 ◽  
Vol 94 (47) ◽  
pp. 1869-1870
Author(s):  
Balestra ◽  
Nüesch
Keyword(s):  
Rocky Mountains ◽  
Spotted Fever ◽  
Rocky Mountain ◽  
Rickettsia Conorii ◽  
Rocky Mountain Spotted Fever ◽  
Klinische Diagnose ◽  
Rickettsia Rickettsii

Eine 37-jährige Patientin stellt sich nach der Rückkehr von einer Rundreise durch Nordamerika mit einem Status febrilis seit zehn Tagen und einem makulösem extremitätenbetontem Exanthem seit einem Tag vor. Bei suggestiver Klinik und Besuch der Rocky Mountains wird ein Rocky Mountain spotted fever diagnostiziert. Die Serologie für Rickettsia conorii, die mit Rickettsia rickettsii kreuzreagiert, war positiv und bestätigte die klinische Diagnose. Allerdings konnte der beweisende vierfache Titeranstieg, möglicherweise wegen spät abgenommener ersten Serologie, nicht nachgewiesen werden. Nach zweiwöchiger antibiotischer Therapie mit Doxycycline waren Status febrilis und Exanthem regredient.

Tectonic controls on basement exhumation in the southern Rocky Mountains (United States): The power of combined zircon (U-Th)/He and K-feldspar 40Ar/39Ar thermochronology

Geology ◽  
2021 ◽  
Author(s):  
Jason W. Ricketts ◽  
Jacoup Roiz ◽  
Karl E. Karlstrom ◽  
Matthew T. Heizler ◽  
William R. Guenthner ◽  
...  
Keyword(s):  
Rocky Mountains ◽  
Rocky Mountain ◽  
Snowball Earth ◽  
Southern Rocky Mountains ◽  
Basement Rocks ◽  
Rocky Mountain Region ◽  
Multi Stage ◽  
Inverse Models ◽  
Multiple Pulses ◽  
Differential Uplift

The Great Unconformity of the Rocky Mountain region (western North America), where Precambrian crystalline basement is nonconformably overlain by Phanerozoic strata, represents the removal of as much as 1.5 b.y. of rock record during 10-km-scale basement exhumation. We evaluate the timing of exhumation of basement rocks at five locations by combining geologic data with multiple thermochronometers. 40Ar/39Ar K-feldspar multi-diffusion domain (MDD) modeling indicates regional multi-stage basement cooling from 275 to 150 °C occurred at 1250–1100 Ma and/or 1000–700 Ma. Zircon (U-Th)/He (ZHe) dates from the Rocky Mountains range from 20 to 864 Ma, and independent forward modeling of ZHe data is also most consistent with multi-stage cooling. ZHe inverse models at five locations, combined with K-feldspar MDD and sample-specific geochronologic and/or thermochronologic constraints, document multiple pulses of basement cooling from 250 °C to surface temperatures with a major regional basement exhumation event 1300–900 Ma, limited cooling in some samples during the 770–570 Ma breakup of Rodinia and/or the 717–635 Ma snowball Earth, and ca. 300 Ma Ancestral Rocky Mountains cooling. These data argue for a tectonic control on basement exhumation leading up to formation of the Precambrian-Cambrian Great Unconformity and document the formation of composite erosional surfaces developed by faulting and differential uplift.

scholarly journals Autumn Raptor Migration in Yellowstone National Park, 2011–2015

2018 ◽  
Vol 131 (4) ◽  
pp. 303-311
Author(s):  
Lisa M. Baril ◽  
David B. Haines ◽  
Lauren E. Walker ◽  
Douglas W. Smith
Keyword(s):  
Rocky Mountains ◽  
Yellowstone National Park ◽  
National Park ◽  
Rocky Mountain ◽  
Cost Effective ◽  
Single Species ◽  
Future Research ◽  
Individual Species ◽  
Relative Role ◽  
Stopover Site

Raptors are wide-ranging, vagile avian predators whose populations can be difficult and costly to monitor on their breeding or winter range. However, monitoring raptors during their annual northbound or southbound migration is a cost-effective and efficient alternative to time-intensive, single-species breeding surveys. In 2010, we observed numerous Swainson’s Hawks (Buteo swainsoni) and Red-tailed Hawks (Buteo jamaicensis) migrating through the Hayden Valley in central Yellowstone National Park, prompting an investigation into raptor migration patterns in the park. Our objectives were to monitor annual autumn raptor migration in Hayden Valley from 2011 to 2015 and to determine the relative role of this undocumented migration site by comparing our observations to simultaneously collected migration data from three other sites in the Rocky Mountain Flyway. From 2011 to 2015, we observed 6441 raptors of 17 species across 170 d and 907 h of observation. Red-tailed Hawks, Swainson’s Hawks, and Golden Eagles (Aquila chrysaetos) accounted for 51% of the total individuals observed over five years. Overall counts from Hayden Valley were comparable to counts from the three migration sites in the Rocky Mountains, although abundance of individual species varied by site. Data from this study suggest that Hayden Valley may serve as a stopover site for migrating raptors and presents an opportunity for future research. By improving our understanding of where raptors migrate and the characteristics of stopover areas in the Rocky Mountains, land managers may develop effective strategies for protecting raptor populations and habitat from threats including development and climate change.

THE ROCKY MOUNTAIN TRENCH: A PROBLEM

1964 ◽  
Vol 1 (3) ◽  
pp. 184-205 ◽  
Author(s):  
C. H. Crickmay
Keyword(s):  
Rocky Mountains ◽  
Rocky Mountain ◽  
Canadian Rocky Mountains ◽  
The West ◽  
West Side ◽  
Combined Action ◽  
Headward Erosion

The Rocky Mountain Trench is defined as the 1 000-mile valley which marks the west side of the Canadian Rocky Mountains. The background of the Trench as a problem is examined, and descriptions, geographical and geological, are given. Previous work on Trench origin is reviewed and note is taken of the seeming inapplicability of accepted erosion theories to the making of the erosion-made Trench. An hypothesis is offered in which the combined action of drainage hemmed in by bordering uplifts, guided headward erosion, lateral corrasion, and streams repeatedly reversed by continuing diastrophism is suggested as the excavator of the Trench, a valley characterized by the puzzling peculiarity of continuous depth without a consistent gradient.

scholarly journals Provenance of Pennsylvanian–Permian sedimentary rocks associated with the Ancestral Rocky Mountains orogeny in southwestern Laurentia: Implications for continental-scale Laurentian sediment transport systems

Lithosphere ◽  
2020 ◽  
Vol 12 (1) ◽  
pp. 88-121 ◽  
Author(s):  
Ryan J. Leary ◽  
Paul Umhoefer ◽  
M. Elliot Smith ◽  
Tyson M. Smith ◽  
Joel E. Saylor ◽  
...  
Keyword(s):  
Sediment Transport ◽  
Rocky Mountains ◽  
Detrital Zircon ◽  
Rocky Mountain ◽  
Sedimentary Basins ◽  
The Arctic ◽  
Transport Systems ◽  
Published Data ◽  
Transport Pathways ◽  
Continental Scale

Abstract The Ancestral Rocky Mountains system consists of a series of basement-cored uplifts and associated sedimentary basins that formed in southwestern Laurentia during Early Pennsylvanian–middle Permian time. This system was originally recognized by aprons of coarse, arkosic sandstone and conglomerate within the Paradox, Eagle, and Denver Basins, which surround the Front Range and Uncompahgre basement uplifts. However, substantial portions of Ancestral Rocky Mountain–adjacent basins are filled with carbonate or fine-grained quartzose material that is distinct from proximal arkosic rocks, and detrital zircon data from basins adjacent to the Ancestral Rocky Mountains have been interpreted to indicate that a substantial proportion of their clastic sediment was sourced from the Appalachian and/or Arctic orogenic belts and transported over long distances across Laurentia into Ancestral Rocky Mountain basins. In this study, we present new U-Pb detrital zircon data from 72 samples from strata within the Denver Basin, Eagle Basin, Paradox Basin, northern Arizona shelf, Pedregosa Basin, and Keeler–Lone Pine Basin spanning ∼50 m.y. and compare these to published data from 241 samples from across Laurentia. Traditional visual comparison and inverse modeling methods map sediment transport pathways within the Ancestral Rocky Mountains system and indicate that proximal basins were filled with detritus eroded from nearby basement uplifts, whereas distal portions of these basins were filled with a mix of local sediment and sediment derived from marginal Laurentian sources including the Arctic Ellesmerian orogen and possibly the northern Appalachian orogen. This sediment was transported to southwestern Laurentia via a ca. 2,000-km-long longshore and aeolian system analogous to the modern Namibian coast. Deformation of the Ancestral Rocky Mountains slowed in Permian time, reducing basinal accommodation and allowing marginal clastic sources to overwhelm the system.

THE ATHABASCA VALLEY ERRATICS TRAIN, ALBERTA AND PLEISTOCENE ICE MOVEMENTS ACROSS THE CONTINENTAL DIVIDE

1967 ◽  
Vol 4 (4) ◽  
pp. 625-632 ◽  
Author(s):  
M. A. Roed ◽  
E. W. Mountjoy ◽  
N. W. Rutter
Keyword(s):  
British Columbia ◽  
Rocky Mountains ◽  
Late Stage ◽  
National Park ◽  
Rocky Mountain ◽  
Metamorphic Rocks ◽  
Jasper National Park ◽  
Continental Divide ◽  
Park Area

The Athabasca Valley Erratics Train contains a variety of low- to medium- grade metamorphic rocks, the most abundant of which is talcose schist, with lesser amounts of garnet schist and biotite–quartz schist. This erratics train occurs in and west of the Athabasca Valley west of Edson, Alberta. It is probably a late stage deposit of the same glacier that carried and deposited the Erratics Train, Foothills of Alberta. The metamorphic erratics were incorporated into a glacier that originated in the northern part of the Monashee Mountains and Premier Range of British Columbia. This ice movement is also recorded by numerous U-shaped valleys, which extend across the Continental Divide. Thus, during a brief period in late(?) Wisconsin time, the Cordilleran ice in the Rocky Mountains of the Jasper National Park area was partly derived from west of the Continental Divide and the Rocky Mountain Trench. These data agree with the inferred ice movements shown on the 1958 Glacial Map of Canada.

DEEP CRUSTAL STRUCTURE UNDER THE PLAINS AND ROCKY MOUNTAINS

1966 ◽  
Vol 3 (7) ◽  
pp. 937-945 ◽  
Author(s):  
E. R. Kanasewich
Keyword(s):  
Rocky Mountains ◽  
Upper Mantle ◽  
Vertical Motion ◽  
Rocky Mountain ◽  
The United States ◽  
Continental Margins ◽  
Low Velocity ◽  
Mountain System ◽  
Deep Crustal Structure ◽  
Small Roots

The Airy hypothesis of isostatic compensation is very useful in accounting for structural differences between oceans and the continental margins. However, within the continents the compensation mechanism becomes more complicated. The thickness of the crust under much of the plains in the United States and Canada is between 40 and 55 kilometers. Determinations of crustal thickness under the Rocky Mountains gives results between 30 and 50 kilometers. Although local mountain ranges may have small roots, the Cordilleran region does not have a crustal root when compared to the plains. It follows that a modified form of Pratt's hypothesis of isostasy must be applied to continental regions. The density of the upper mantle is then different under the plains from what it is under the Rocky Mountains. In the plains it appears that there is a broad conformity of the Precambrian basement surface and the Mohorovicic discontinuity. Therefore the cause of epeirogenesis must lie within the upper mantle, possibly at the level of Gutenberg's low-velocity layer. The crustal studies in the plains and mountains indicate that more consideration should be given to gravitational gliding tectonics in the development of the Rocky Mountain system, since it is possible that there was substantial vertical motion of large crustal blocks.

Conductive structures under the Canadian Rocky Mountains

1985 ◽  
Vol 22 (3) ◽  
pp. 384-398 ◽  
Author(s):  
D. K. Bingham ◽  
D. I. Gough ◽  
M. R. Ingham
Keyword(s):  
Rocky Mountains ◽  
Transfer Functions ◽  
Three Dimensional ◽  
Vertical Component ◽  
Rocky Mountain ◽  
Auroral Zone ◽  
Event Analysis ◽  
Canadian Rocky Mountains ◽  
Period Range ◽  
Single Station

The paper reports results from an array of 33 three-component magnetometers that recorded time-varying fields in 1981 over an area of some 56 000 km2 in the Canadian Cordillera. The array was centred at Tête Jaune Cache in the Rocky Mountain Trench, where a large magnetovariation anomaly had been located in an earlier array study. It was bisected by the trench and extended to the northeast across the Rocky Mountains to the Alberta Foothills and to the southwest across the Cariboo and Monashee mountains. Magnetograms and Fourier transform maps covering the period range 10–91 min show strong attenuation of the vertical component, Z, southwest of the Rocky Mountain Trench, with very large Z amplitudes in the Main Ranges of the Rockies. The horizontal components show an elongated anomaly along the Rocky Mountains Main Ranges and Trench, with three-dimensional features superimposed. The conductive structures include a highly conductive layer, probably in the lower crust, southwest of the trench and a conductive ridge rising into the upper crust near the edge of that layer. Current models have been fitted to observed vertical -and horizontal-component anomalies and show that both layer and ridge are necessary for a fit and that the ridge is 50–80 km wide. Single-station transfer functions at periods of 10 and 22 min have been calculated from a number of variation events of various polarizations, to reduce any displacement of the anomalies by auroral-zone source currents. Artificial-event analysis, with these transfer functions, shows that the conductive ridge lies under the Main Ranges of the Rockies and not under the trench. Its great width indicates a structure of major tectonic significance, which will be considered in another paper.

Distribution of Dermacentor andersoni (Acari: Ixodidae) in Grassland Regions of Alberta, Canada

2021 ◽  
Author(s):  
Timothy J Lysyk ◽  
Shaun J Dergousoff ◽  
Kateryn Rochon ◽  
Neil B Chilton ◽  
Anne M Smith
Keyword(s):  
Rocky Mountains ◽  
Rocky Mountain ◽  
Winter Precipitation ◽  
Dermacentor Andersoni ◽  
Tick Density ◽  
Northerly Direction ◽  
Westerly Direction ◽  
Previous Summer ◽  
Rocky Mountain Wood Tick ◽  
Soil Groups

Abstract The geographic distribution of the Rocky Mountain wood tick, Dermacentor andersoni Stiles, was determined in Alberta, Canada, by drag sampling at 86 and 89 sites during 2011 and 2012, respectively. Tick density and prevalence varied between years, averaging (range) 1.0 (0–26.2) and 5.9 (0–110) ticks/1,000 m2 in 2011 and 2012, respectively. Ticks were detected at 24.4% and 42.7% of the sites sampled in each respective year. Tick density and presence declined in a northerly direction to 51.6°N and in a westerly direction to ca. 113°W, except for a small area of high density at the edge of the Rocky Mountains in the southeastern portion of the province. Ticks were most abundant in the Dry Mixedgrass and Montane natural subregions and in areas with Brown Chernozemic, Regosol, and Solodized Solonetzic great soil groups. A logistic regression model indicated that tick presence was increased in the Dry Mixedgrass natural subregion and in regions with greater temperatures during the previous summer and normal winter precipitation but was reduced in areas with Dark Brown Chernozemic soils. The model will be useful for predicting tick presence and the associated risk of tick-borne diseases in the province.

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