Stratigraphy and deformational history of the Scrip Nappe, Monashee Mountains, British Columbia

1983 ◽  
Vol 20 (4) ◽  
pp. 639-650 ◽  
Author(s):  
Robert P. Raeside ◽  
Philip S. Simony
Keyword(s):  
British Columbia ◽  
Lower Limb ◽  
Rocky Mountains ◽  
Metamorphic Grade ◽  
Deformational History ◽  
Crenulation Cleavage ◽  
Deformation Phase ◽  
Nappe Complex ◽  
Selkirk Mountains ◽  
History Of

The Scrip Nappe, a large recumbent anticline that occupies the northern Selkirk and northern Monashee Mountains, has an inverted lower limb, some 50 km in length across strike, and comprises stratigraphic divisions of the Hadrynian Horsethief Creek Group, which can be traced southward with decreasing metamorphic grade through the Selkirk Mountains to the northern Purcell Mountains. The Scrip Nappe has a southwesterly vergence and it formed that way during the first folding phase of the Mesozoic Columbian Orogeny. Metamorphism no greater than biotite zone accompanied that first deformation. The nappe was subsequently refolded into tight northeast verging folds. Metamorphism rose to upper amphibolite facies late in the second deformation phase. After the metamorphic climax, northeast verging buckle folds and associated crenulation cleavage formed locally during a third folding episode. The entire nappe complex was then carried northeastward, on the Purcell thrust, over the folds and thrusts of the western Rocky Mountains.

scholarly journals Mesostructures and deformational history of the Central Crystallines: an example from Garhwal Himalaya, India

1998 ◽  
Vol 17 ◽  
Author(s):  
V. K. Singh ◽  
S. P. Singh ◽  
P. S. Saklani ◽  
C. S. Dubey
Keyword(s):  
Large Scale ◽  
Ductile Deformation ◽  
Metamorphic Rocks ◽  
Geochronological Data ◽  
Deformational History ◽  
Crenulation Cleavage ◽  
Ductile Shearing ◽  
History Of ◽  
Transcurrent Faults ◽  
East West

Structural analysis reveals that the Central Crystallines in the Garhwal region were subjected to four phases of deformations (D1 to D4). The D1 deformational phase is highly obliterated and usually found as F1 intrafolial (rootless) tight isoclinal folds in migmatites and gneisses. The D2 deformational phase produced strong pervasive S2 schistosity and asymmetric and open fold (F2) plunging 20-30° towards ENE-WSW. The L2 lineation plunge 5-10° towards east-west is well developed in medium grade metamorphic rocks. The D1 deformations were responsible for F3 folds reflected in large scale anticlinal and synclinal, overturned and recumbent folds, which have 10-40° plunges towards NW. The late D3 deformational stresses were responsible for shearing along the middle limbs of F1 folds and they ultimately initiated thrusting. The NNE­ SSW plunging mineral or stretching lineation (L3), S3 crenulation cleavage and S-C fabrics were developed during the dominant ductile shearing related to the late D3 deformation. The D4 phase characterised by brittle-ductile deformation (minor kinks, puckers, transverse/transcurrent faults, and S-C' fabrics) and extensive cataclasis along thrust- and fault-zones reflects the last episode of deformation. The structural and geochronological data indicate that D1 and D2 deformation episodes may be related to the Precambrian time while D3 and D4 are exclusively of the Tertiary age.

Stratigraphy, sedimentology, and regional correlation of the Horsethief Creek Group (Hadrynian, Late Precambrian) in the northern Purcell and Selkirk Mountains, British Columbia

1980 ◽  
Vol 17 (12) ◽  
pp. 1708-1724 ◽  
Author(s):  
T. P. Poulton ◽  
P. S. Simony
Keyword(s):  
British Columbia ◽  
Rocky Mountains ◽  
Submarine Fan ◽  
Source Areas ◽  
Late Precambrian ◽  
Coarse Sediment ◽  
Regional Correlation ◽  
Selkirk Mountains ◽  
Igneous Activity ◽  
Thickness Variations

The Hadrynian Horsethief Creek Group in the northernmost Purcell Mountains and adjacent Selkirk Mountains is subdivisible regionally into grit, slate, carbonate, and upper clastic divisions in upward succession. The grit division represents a submarine fan assemblage and the slate division hemipelagic muds probably deposited in intermediate depths. The carbonate division comprises an interval of discontinuous lenses representing "bahamian" carbonate bank and off-bank assemblages, and the upper clastic division is a heterogeneous clastic wedge, which shows some evidence of northerly and westerly increasing depositional depths. Feldspathic quartz pebble conglomerate beds intercalated with the carbonates in both bank and off-bank facies indicate tectonic activation of granitic source areas like those from which similar rocks in the upper part of the Miette Group of the Rocky Mountains were derived.The upper part of the slate division, which can be differentiated in western localities as a distinct semipelite–amphibolite unit, and the upper clastic division each expand in thickness northwestward to dominate the Horsethief Creek outcrops in the Selkirk Mountains. These thickness variations, the increase of amphibolite northward in the semipelite–amphibolite unit, and the loss of grit beds northward in the slate division suggest deposition in a depocentre that received coarse sediment from southerly and easterly directions, and that became the site of mafic igneous activity.

Metamorphism in the Solitude Range, southwestern Rocky Mountains, British Columbia: comparison with adjacent Omineca Belt rocks and tectonometamorphic implications for the Purcell Thrust

1990 ◽  
Vol 27 (11) ◽  
pp. 1511-1520 ◽  
Author(s):  
L. P. Gal ◽  
E. D. Ghent
Keyword(s):  
British Columbia ◽  
Rocky Mountains ◽  
Rocky Mountain ◽  
Metamorphic Grade ◽  
Normal Faulting ◽  
Physical Conditions ◽  
Big Bend

Rocks of the Solitude Range, British Columbia, have been metamorphosed from chloritoid–chorite-zone to kyanite-zone conditions. The grade of metamorphism increases southwestward toward the Rocky Mountain Trench (RMT) and the Omineca Belt. Isograds crosscut lithologies and trend more northerly than deformation 2 (D2) structures and the RMT. They are thought to have been quenched syn- to post-D2. Pelitic (Mahto Formation) and calc-pelitic (Tsar Creek unit) rocks contain assemblages that reflect the increase in metamorphic grade. Physical conditions of metamorphism are estimated to be approximately 450–540 °C from the garnet to the kyanite zone; pressures averaged 6–7 kbar (1 kbar = 100 MPa). The pressures, temperatures, and metamorphic assemblages are very similar to those of the Adamant Range, which lies across the Purcell Thrust, to the southwest. This is in contrast with the Big Bend area, to the northwest, where differences in pressure across the Purcell Thrust (PT) have been documented. Two possible models to explain these contrasting relationships are presented. One model suggests that there was post-movement heating on the PT, which reduced the metamorphic contrast across the PT. The second model suggests that a combination of thrust and normal faulting, including warping of isobaric surfaces, has produced an apparently unbroken metamorphic sequence across the PT.

On the Life History of the Douglas-fir Cone Moth, Barbara colfaxiana (Kft.) (Lepidoptera: Olethreutidae), and one of its Parasites, Glypta evetriae Cush. (Hymenoptera: Ichneumonidae)

1960 ◽  
Vol 92 (11) ◽  
pp. 826-834 ◽  
Author(s):  
A. F. Hedlin
Keyword(s):  
British Columbia ◽  
Life History ◽  
Rocky Mountains ◽  
Pacific Coast ◽  
Douglas Fir ◽  
Lake Area ◽  
Seed Loss ◽  
The Pacific ◽  
History Of ◽  
Loss Range

The Douglas-fir cone moth has been reported causing damage to cones and seeds of Douglas fir for a number of years; reports of seed loss range from light to almost 100 per cent. The insect occurs throughout the range of the host in British Columbia, the Pacific Coast States, and the Rocky Mountains.Observations recorded here were made during 1957 and 1958 in the Cowichan Lake area of Vancouver Island, and 1959 in the interior of British Columbia.

Multiple Glaciation in Central British Columbia

1971 ◽  
Vol 8 (7) ◽  
pp. 743-752 ◽  
Author(s):  
Howard W. Tipper
Keyword(s):  
British Columbia ◽  
Rocky Mountains ◽  
Ice Sheet ◽  
Glacial History ◽  
Ample Evidence ◽  
Coast Mountains ◽  
Lacustrine Deposits ◽  
Glacier Ice ◽  
History Of

During Fraser Glaciation central British Columbia was covered by glacier ice that accumulated in the Coast and Cariboo Mountains, flowed inwardly as a piedmont glacier to the Interior Plateau and thence northeasterly as an ice sheet toward the Rocky Mountains. After withdrawal of the Fraser ice sheet a limited re-advance of ice from Cariboo and Coast Mountains took place but not as a coalescent ice sheet. Drumlinoid forms, eskers, meltwater channels, kettled deposits, and lacustrine deposits provide ample evidence from which a glacial history of the area can be deduced. Although Fraser Glaciation is not believed to have culminated as an ice dome over central British Columbia, there is some evidence to suggest that earlier glaciations did form such a dome from which ice flowed radially over the Coast and Rocky Mountains.

Conodont biostratigraphy of the latest Cambrian - Early Ordovician upper McKay Group, southeastern British Columbia

2007 ◽  
Vol 44 (12) ◽  
pp. 1713-1740 ◽  
Author(s):  
Leanne J Pyle ◽  
Christopher R Barnes ◽  
Lee McKenzie McAnally
Keyword(s):  
British Columbia ◽  
Rocky Mountains ◽  
Canadian Rocky Mountains ◽  
Conodont Biostratigraphy ◽  
Northern Rocky Mountains ◽  
Early Ordovician ◽  
Low Diversity ◽  
History Of ◽  
Conodont Fauna ◽  
Thermal Subsidence

The age of the upper McKay Group based on conodont biostratigraphy is latest Cambrian (Cordylodus proavus Zone) to late Early Ordovician (middle Floian; Oepikodus communis Zone). A collection of 12 940 conodont elements was recovered from 306 samples of upper McKay Group strata exposed in the Western Main Ranges of the southern Canadian Rocky Mountains, southeastern British Columbia. The conodont fauna is assigned to 53 species representing 30 genera. Twelve zones are recognized, two of which are cosmopolitan: Cordylodus proavus Zone and Iapetognathus Zone. Seven Midcontinent Realm zones, in ascending order, include Polycostatus falsioneotensis, Rossodus tenuis, Rossodus manitouensis, low diversity interval, Scolopodus subrex, and Acodus kechikaensis zones, and Tropodus sweeti Subzone (of the Oepikodus communis Zone). Three Atlantic Realm zones, in ascending order, include Cordylodus angulatus, Acodus deltatus, and Paroistodus proteus zones. The zonation for the upper McKay Group establishes correlation with the Survey Peak Formation and lower Outram Formation of the Bow Platform, and with the Kechika Formation and lower Skoki Formation of the Macdonald Platform and Kechika Trough in the northern Rocky Mountains. The McKay Group represents deposition during post-rift thermal subsidence of the margin, although its thickness, abrupt transition to black shale of the overlying Glenogle Formation, and intercalation of volcanogenic rocks imply a history of differential subsidence similar to that of the northern Cordillera, probably related to periodic extension.

Metasedimentary rocks, intrusions and deformation history in the south-east part of the c. 1800 Ma Ketilidian orogen, South Greenland: Project SUPRASYD 1996

1997 ◽  
pp. 60-65
Author(s):  
Adam A. Garde ◽  
Brian Chadwick ◽  
John Grocott ◽  
Cees Swager
Keyword(s):  
Field Work ◽  
Deformation History ◽  
The South ◽  
Present Contribution ◽  
East Part ◽  
Metasedimentary Rocks ◽  
Deformational History ◽  
Base Camp ◽  
History Of ◽  
Geological Map

NOTE: This article was published in a former series of GEUS Bulletin. Please use the original series name when citing this article, for example: Garde, A. A., Chadwick, B., Grocott, J., & Swager, C. (1997). Metasedimentary rocks, intrusions and deformation history in the south-east part of the c. 1800 Ma Ketilidian orogen, South Greenland: Project SUPRASYD 1996. Geology of Greenland Survey Bulletin, 176, 60-65. https://doi.org/10.34194/ggub.v176.5063 _______________ The south-east part of the c. 1800 Ma Ketilidian orogen in South Greenland (Allaart, 1976) is dominated by strongly deformed and variably migmatised metasedimentary rocks known as the ‘Psammite and Pelite Zones’ (Chadwick & Garde, 1996); the sediments were mainly derived from the evolving Julianehåb batholith which dominates the central part of the orogen. The main purpose of the present contribution is to outline the deformational history of the Psammite Zone in the region between Lindenow Fjord and Kangerluluk (Fig. 2), investigated in 1994 and 1996 as part of the SUPRASYD project (Garde & Schønwandt, 1995 and references therein; Chadwick et al., in press). The Lindenow Fjord region has high alpine relief and extensive ice and glacier cover, and the fjords are regularly blocked by sea ice. Early studies of this part of the orogen were by boat reconnaissance (Andrews et al., 1971, 1973); extensive helicopter support in the summers of 1992 and 1994 made access to the inner fjord regions and nunataks possible for the first time.A preliminary geological map covering part of the area between Lindenow Fjord and Kangerluluk was published by Swager et al. (1995). Hamilton et al. (1996) have addressed the timing of sedimentation and deformation in the Psammite Zone by means of precise zircon U-Pb geochronology. However, major problems regarding the correlation of individual deformational events and their relationship with the evolution of the Julianehåb batholith were not resolved until the field work in 1996. The SUPRASYD field party in 1996 (Fig. 1) was based at the telestation of Prins Christian Sund some 50 km south of the working area (Fig. 2). In addition to base camp personnel, helicopter crew and the four authors, the party consisted of five geologists and M.Sc. students studying mafic igneous rocks and their mineralisation in selected areas (Stendal et al., 1997), and a geologist investigating rust zones and areas with known gold anomalies.

Sacral plexus disorder caused by a wooden toothpick in the rectum

2021 ◽  
Vol 14 (1) ◽  
pp. e238690
Author(s):  
Takuro Endo ◽  
Taku Sugawara ◽  
Naoki Higashiyama
Keyword(s):  
Lower Limb ◽  
Spinal Nerve ◽  
Leg Pain ◽  
Sacral Plexus ◽  
Lateral Recess ◽  
Lateral Recess Stenosis ◽  
Preoperative Ct ◽  
History Of ◽  
History Of Pain ◽  
The Right

A 67-year-old man presented with a 2-month history of pain in his right buttock and lower limb. MRI depicted right L5/S1 lateral recess stenosis requiring surgical treatment; however, preoperative CT showed an approximately 7 cm long, thin, rod-shaped structure in the rectum, which was ultimately determined to be an accidentally ingested toothpick. It was removed surgically 6 days after diagnosis, because right leg pain worsened rapidly. The pain disappeared thereafter, and the symptoms have not recurred since. The pain might have been localised to the right buttock and posterior thigh in the early stages because the fine tip of the toothpick was positioned to the right of the anterior ramus of the S2 spinal nerve. Although sacral plexus disorder caused by a rectal foreign body is extremely rare, physicians should be mindful to avoid misdiagnosis.

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