Transverse folding and superposed deformation, Mount Fisher area, southern Canadian Rocky Mountain thrust and fold belt

1982 ◽  
Vol 19 (5) ◽  
pp. 1011-1024 ◽  
Author(s):  
M. E. McMechan ◽  
R. A. Price
Keyword(s):  
Rocky Mountain ◽  
Normal Faults ◽  
Fold Belt ◽  
East Side ◽  
Dominant Structure ◽  
Southern Rocky Mountain ◽  
Middle Proterozoic

A northeast-facing panel of Middle Proterozoic (Purcell Supergroup) strata occurs beneath Cambrian and Devonian strata along the east side of the Rocky Mountain Trench in the Mount Fisher area. Anomalous northeast-trending folds, faults, and cleavage that formed during Cretaceous–Paleocene deformation occur in this panel in the northern part of the area. The dominant structure in the southern part is the northwest-trending Lizard segment of the (Mesozoic) Hosmer nappe, which folds an older north-trending cleavage that probably formed during the East Kootenay Orogeny (1300–1350 Ma). Thickness and facies variations in Purcell strata and changes in the level of erosion beneath the sub-Devonian unconformity imply that many of the important structural boundaries in the Mount Fisher area and also the normal faults along the southern Rocky Mountain Trench follow the locus of older structures that were active in the Middle Proterozoic and the early Paleozoic.The anomalous northeast-trending structures in the Mount Fisher and adjacent areas formed because the underlying Hosmer thrust developed across a major, pre-Devonian, northwest-facing drape fold, the Dibble Creek monocline. Ramps connecting bedding-glide zones were deflected across the monocline, and strata were gravitationally compressed to form northeast-trending folds, faults, and cleavage as they were displaced up the monocline along the Moyie – Dibble Creek fault.

scholarly journals Reconnaissance for mineral occurrences in North-East Greenland (76°–78°N)

1994 ◽  
Vol 162 ◽  
pp. 163-168
Author(s):  
S.M Jensen ◽  
H Stendal
Keyword(s):  
Present Knowledge ◽  
Stream Sediment ◽  
Normal Faults ◽  
Fold Belt ◽  
East Greenland ◽  
Geochemical Anomalies ◽  
North East ◽  
Economic Significance ◽  
Incompatible Elements ◽  
Middle Proterozoic

Reconnaissance for indications of potentially economic mineralisation in the Caledonian fold belt of North-East Greenland has shown that stream sediment geochemical anomalies and mineral occurrences are related to Lower-Middle Proterozoic and Caledonian skarns, Caledonian shear and thrust zones, and breccias in post-Jurassic normal faults. None of the mineral showings are of economic significance. Mineralised rock samples, stream sediment silt samples and panned stream sediment heavy mineral concentrates generally have low contents of metals and incompatible elements, and only few areas stand out as being geochronically anomalous. On the basis of the present knowledge of the geology of the region the mineral potential is considered low.

Proterozoic gneisses of the Malton Complex, near Valemount, British Columbia: U–Pb ages and Nd isotopic signatures

1991 ◽  
Vol 28 (8) ◽  
pp. 1202-1216 ◽  
Author(s):  
Michael R. McDonough ◽  
Randall R. Parrish
Keyword(s):  
British Columbia ◽  
Rocky Mountain ◽  
Granite Gneiss ◽  
Canadian Shield ◽  
Crustal Material ◽  
East Side ◽  
Complex Span ◽  
Late Proterozoic ◽  
Zircon Crystallization ◽  
Southern Rocky Mountain

Proterozoic gneisses of the Malton Complex in the vicinity of Valemount, British Columbia, occur in a series of lithologically and structurally complex, fault-bounded slices of crystalline basement and interleaved cover. Gneisses of the Malton Complex span the Southern Rocky Mountain Trench and underlie the western part of the Rocky Mountain fold and thrust belt and the eastern part of the Omineca Belt of the Canadian Cordillera. Structural and stratigraphic relationships indicate that they formed the basement upon which an enigmatic quartzite unit and the Late Proterozoic Windermere Supergroup were deposited.The Yellowjacket and Bulldog gneisses, on the east side of the Rocky Mountain Trench, have yielded four U–Pb zircon crystallization ages of ca. 1870 Ma, with εNd(T) values of −2.6 to −3.4. The Hugh Allan gneiss, also on the east side of the trench but separated from the Yellowjacket gneiss by a major thrust fault, includes leucocratic granite gneiss having a zircon U–Pb age of [Formula: see text], which has intruded an older (undated) lithologically heterogeneous assemblage of gneiss. The basal Windermere succession of the Valemount region is inferred to be younger than ca. 740 Ma, since these intrusions are not found within the Late Proterozoic stratified rocks.Augen granitoid orthogneiss of the Malton Range on the west side of the Rocky Mountain Trench has been dated as [Formula: see text] using zircons. A second sample yields data suggesting an age between 2050 and 2100 Ma, but its interpretation is uncertain because of scatter in analyses and possible zircon inheritance. The latter sample has an εNd(T) at 1990 Ma of −2.6. Nd model ages for the Malton, Yellowjacket, and Bulldog samples range from 2.45 to 2.56 Ga, indicating that the igneous protoliths were derived from a source that probably had some component of Archean crustal material involved.The U–Pb ages and Nd model ages are quite similar to those of rocks underlying portions of Alberta and the western Canadian Shield, specifically the Fort Simpson terrane, the Great Bear magmatic zone, and parts of the Thelon–Taltson arc. This evidence, as well as structural and stratigraphic arguments, links the Malton Complex gneisses with those of the Canadian Shield, precluding their derivation by large-magnitude displacements from the southwestern United States. Structural analysis indicates that they restore to locations 100–200 km southwest of their present exposure.Structural, stratigraphic, and isotopic data indicate that the Southern Rocky Mountain Trench is not a suture.

EMPLACEMENT STYLE OF A POST-CALDERA INTRUSION: INSIGHTS FROM STRUCTURE AND MAGNETIC ANISOTROPY OF THE ALAMOSA RIVER PLUTON (SOUTHERN ROCKY MOUNTAIN VOLCANIC FIELD, COLORADO)

2018 ◽  
Author(s):  
Filip Tomek ◽  
◽  
Michael S. Petronis ◽  
Michael S. Petronis ◽  
Amy K. Gilmer ◽  
...  
Keyword(s):  
Magnetic Anisotropy ◽  
Rocky Mountain ◽  
Volcanic Field ◽  
Southern Rocky Mountain

scholarly journals Supplemental Material: Postcaldera intrusive magmatism at the Platoro caldera complex, Southern Rocky Mountain volcanic field, Colorado, USA

2021 ◽  
Author(s):  
A.K. Gilmer ◽  
et al.
Keyword(s):  
Trace Element ◽  
Rocky Mountain ◽  
Volcanic Field ◽  
Trace Element Geochemistry ◽  
Zircon Geochronology ◽  
Element Geochemistry ◽  
Isotopic Compositions ◽  
Southern Rocky Mountain

<div>Table S1: Whole-rock compositions of analyzed samples. Table S2: Major and trace element geochemistry of feldspar. Table S3: Major and trace element geochemistry of pyroxene. Table S4: Major and trace element geochemistry of biotite. Table S5: Major and trace element geochemistry of amphibole. Table S6: Zircon geochronology and trace element geochemistry. Table S7: Lutetium and hafnium isotopic compositions of zircon. Table S8: Amphibole-plagioclase thermometry. Table S9: Sample locations and lithologies.<br></div>

A study of microseismicity in Northern Baja California, Mexico

1976 ◽  
Vol 66 (6) ◽  
pp. 1921-1929 ◽  
Author(s):  
Tracy L. Johnson ◽  
Juan Madrid ◽  
Theodore Koczynski
Keyword(s):  
Fault Zone ◽  
Focal Mechanism ◽  
Baja California ◽  
Surface Deformation ◽  
Normal Faults ◽  
East Side ◽  
Composite Focal Mechanism ◽  
Agua Blanca Fault ◽  
Eastern Edge ◽  
Low Activity

abstract Five microearthquake instruments were operated for 2 months in 1974 in a small mobile array deployed at various sites near the Agua Blanca and San Miguel faults. An 80-km-long dection of the San Miguel fault zone is presently active seismically, producing the vast majority of recorded earthquakes. Very low activity was recorded on the Agua Blanca fault. Events were also located near normal faults forming the eastern edge of the Sierra Juarez suggesting that these faults are active. Hypocenters on the San Miguel fault range in depth from 0 to 20 km although two-thirds are in the upper 10 km. A composite focal mechanism showing a mixture of right-lateral and dip slip, east side up, is similar to a solution obtained for the 1956 San Miguel earthquake which proved consistent with observed surface deformation.

Protracted Multipulse Emplacement of a Postresurgent Pluton: The Case of Platoro Caldera Complex (Southern Rocky Mountain Volcanic Field, Colorado)

2019 ◽  
Vol 20 (11) ◽  
pp. 5225-5250
Author(s):  
F. Tomek ◽  
A .K. Gilmer ◽  
M. S. Petronis ◽  
P. W. Lipman ◽  
M. S. Foucher
Keyword(s):  
Rocky Mountain ◽  
Volcanic Field ◽  
Southern Rocky Mountain

Structure and tectonic development of the southern Rocky Mountain trench

Tectonics ◽  
1996 ◽  
Vol 15 (3) ◽  
pp. 517-544 ◽  
Author(s):  
Arie J. van der Velden ◽  
Frederick A. Cook
Keyword(s):  
Rocky Mountain ◽  
Tectonic Development ◽  
Southern Rocky Mountain

Classification of glaciers during summer in Southern Rocky Mountain Trench using surface albedo and temperature anomalies

2020 ◽  
Author(s):  
Ali Naeimi ◽  
Martin Sharp
Keyword(s):  
Surface Temperature ◽  
Surface Albedo ◽  
Rocky Mountain ◽  
Surface Melting ◽  
Poor Correlation ◽  
Positive Temperature ◽  
Temperature Anomalies ◽  
Time Periods ◽  
Southern Rocky Mountain ◽  
Snow And Ice

&lt;p&gt;Under most atmospheric conditions, the albedo and temperature of surface snow and ice are two of the main influences on the energy budget for glacier melting. Given that surface albedo and temperature are linked, knowing where and when negative albedo and positive surface temperature anomalies coincide is important for identifying locations and time periods in which anomalously high rates of surface melting are likely. We used measurements from the Moderate Resolution Imaging Spectroradiometer (MODIS) sensors on NASA's AQUA and TERRA satellites&amp;#160;to map the albedo and surface temperature of snow and ice &amp;#160;on glaciers in the of Southern Rocky Mountain Trench ecoregion in the summer months (June-August)&amp;#160;from 2000 to 2018. We use these data to identify specific regions and time periods in which low albedo and high surface temperature coincide since these conditions are likely to support anomalously high rates of surface melting. We also use these data to identify regions/periods in which albedo is particularly low while surface temperature is average or low, since such conditions suggest localized and/or short-term decoupling between the two parameters. We found anomalously low albedo and average/low temperature consistently at multiple glaciers during time periods when there were major forest fire events. We suggest the low albedo results from deposition of pyrogenic carbon from forest fires. We found that, on average, ~25% of the glaciers in the region experienced increasingly negative albedo anomalies and increasingly positive temperature anomalies in summer months from 2000 to 2018. However, we also found that for ~45% of the glaciers that are small, there was a poor correlation between the timing of albedo and temperature anomalies. Our results indicate that the correlation between albedo and temperature was weaker for the small glaciers, and identify specific glaciers that are likely the most vulnerable to climate warming.&lt;/p&gt;

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