Storm-dominated shallow marine deposits: the Fernie–Kootenay (Jurassic) transition, southern Rocky Mountains: Discussion

1981 ◽  
Vol 18 (3) ◽  
pp. 665-666
Author(s):  
L. F. Jansa
Keyword(s):  
Rocky Mountains ◽  
Shallow Marine ◽  
Southern Rocky Mountains ◽  
Marine Deposits

Storm-dominated shallow marine deposits: the Fernie–Kootenay (Jurassic) transition, southern Rocky Mountains

1979 ◽  
Vol 16 (9) ◽  
pp. 1673-1690 ◽  
Author(s):  
Anthony P. Hamblin ◽  
Roger G. Walker
Keyword(s):  
Rocky Mountains ◽  
Tidal Current ◽  
Density Current ◽  
Sedimentary Structure ◽  
Fair Weather ◽  
Shallow Marine ◽  
Southern Rocky Mountains ◽  
Marine Deposits ◽  
Storm Waves ◽  
Lowermost Part

The transition from the Passage Beds of the Fernie into the lowermost part of the Kootenay Formation is exposed in 11 sections in the Crowsnest Pass to Banff area. Six distinct facies can be defined. Facies A (thin bedded turbidites) and facies B (thicker bedded turbidites) both have sole marks indicating north-northwestward flow. Facies C is the most important and consists of interbedded sandstones and shales, with sole marks indicating north-northwestward flow, and "hummocky cross stratification" as the characteristic internal sedimentary structure. It is interpreted to be formed by storm waves in depths below fair-weather wave base. Facies D contains low angle intersecting sets of parallel lamination (beach) and facies E is characterized by trough cross bedding (fluvial). Facies F consists of lenticular sandstones and shales, with coals. The facies occur in the sequence listed and indicate a northward prograding beach complex. Following intense storms, water driven toward the beach surges back seaward, entraining sand and developing into a density current. If deposition from the density current takes place in depths stirred by the storm waves, hummocky cross stratification is formed. In slightly deeper, quieter water the density current deposits a classical turbidite. Thus, the eastward-prograding Kootenay "delta" of previous interpretations now appears to be a northward-prograding beach complex fed by rivers, but with sand transported alongshore by waves. There is no evidence of tidal current activity, and shallow marine deposition is dominated by storms.

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.

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