scholarly journals Cenozoic History of the Southern Rocky Mountains

1975 ◽  
Keyword(s):  
Rocky Mountains ◽  
Southern Rocky Mountains ◽  
History Of

THE TECTONIC SIGNIFICANCE OF MESOSCOPIC SUBFABRICS IN THE SOUTHERN ROCKY MOUNTAINS OF ALBERTA AND BRITISH COLUMBIA

1967 ◽  
Vol 4 (1) ◽  
pp. 39-70 ◽  
Author(s):  
R. A. Price
Keyword(s):  
Rocky Mountains ◽  
Metamorphic Rocks ◽  
Southern Rocky Mountains ◽  
Relative Extension ◽  
Discrete Surfaces ◽  
Tectonic Significance ◽  
Dynamic Analyses ◽  
History Of ◽  
Principal Elements ◽  
Layered Sequence

Deformation throughout much of the southern Rocky Mountains was characterized by brittle failure in a strongly anisotropic layered sequence of non-metamorphic rocks. On a megascopic scale, the overall structure is dominated by an interlocking system of imbricate thrust plates that have moved relatively eastward or northeastward and upward. On a mesoscopic scale, the principal elements in the fabric of these rocks are fractures that are statistically parallel or perpendicular to the bedding, or else intersect it at preferred angles of approximately 25° or 70°. During deformation many of these fractures obviously were kinematically active, as discrete surfaces of slip that became slickensided, as zones of dilation that became filled with vein minerals, or as surfaces of pressure solution that are now marked by stylolites. Each of these fractures provides a partial record of the kinematics of some stage of the deformation, even when they are considered individually rather than as components in a fracture array whose symmetry is related to that of the movement picture during deformation. Each defines a unique line of slip and axis of rotation for slip, or a unique direction of relative extension or compression. Collectively, they provide a direct and succinct record of the kinematic history of an individual fabric domain, and a sound basis for dynamic analyses of deformation.Some preliminary results of a reconnaissance study of these mesoscopic subfabrics illustrate their tectonic significance.A movement picture can be established for the deformation that occurs within an individual thrust plate during its development and translation. Kinematic relationships between and among the interlocking thrust plates can. be studied.Within a broad area centered along the prominent structural reentrant that crosses the Rocky Mountains near Crowsnest Pass, two different movement pictures occur in superposition. Movement about both northerly and north westerly trending axes can be outlined on the basis of the mesoscopic subfabrics of rocks which, on a megascopic scale, have either a northwesterly or a northerly trending fabric axis. Movement patterns for the deformation associated with each of two regional structural salients converge in the vicinity of the reentrant.The mesoscopic subfabrics associated with transverse faults in parts of the Front Ranges outline a pattern of movement which indicates that they did not originate as tear faults related to the translation of the thrust plates, but instead are probably older gravity faults, whose orientation may be controlled by the fabric of the Hudsonian basement extending beneath the mountains from the Canadian Shield.

Redefining the metamorphic history of the oldest rocks in the southern Rocky Mountains

2016 ◽  
Vol 128 (7-8) ◽  
pp. 1207-1227 ◽  
Author(s):  
Ruth F. Aronoff ◽  
Christopher L. Andronicos ◽  
Jeffrey D. Vervoort ◽  
Robert A. Hunter
Keyword(s):  
Rocky Mountains ◽  
Southern Rocky Mountains ◽  
Metamorphic History ◽  
History Of

Pruning to manage white pine blister rust in the southern Rocky Mountains

2011 ◽  
Author(s):  
Amanda Crump ◽  
William R. Jacobi ◽  
Kelly S. Burns ◽  
Brian E. Howell
Keyword(s):  
Rocky Mountains ◽  
White Pine Blister Rust ◽  
White Pine ◽  
Southern Rocky Mountains ◽  
Blister Rust

Linking biophysical models and public preferences for ecosystem service assessments: a case study for the Southern Rocky Mountains

2015 ◽  
Vol 16 (7) ◽  
pp. 2005-2018 ◽  
Author(s):  
Kenneth J. Bagstad ◽  
James M. Reed ◽  
Darius J. Semmens ◽  
Benson C. Sherrouse ◽  
Austin Troy
Keyword(s):  
Rocky Mountains ◽  
Ecosystem Service ◽  
Public Preferences ◽  
Southern Rocky Mountains ◽  
Biophysical Models

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 The Distribution of Glaciers in the Rocky Mountains of the United States

1977 ◽  
Vol 18 (79) ◽  
pp. 325-328 ◽  
Author(s):  
W. L. Graf
Keyword(s):  
United States ◽  
Rocky Mountains ◽  
The United States ◽  
Aerial Photographs ◽  
Northern Rocky Mountains ◽  
Southern Rocky Mountains

AbstractEvidence from aerial photographs, maps, and field checks indicates that 319 glaciers lie in cirques of the Rocky Mountains, south of the United States-Canadian border. On a subcontinental scale, the distribution of glaciers is highly clustered, with larger and denser clusters located in the northern Rocky Mountains. Lesser concentrations of small glaciers occur in the southern Rocky Mountains. The total area of glaciers in the Rocky Mountains of the U.S.A. is 78.9 km2.

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