PERICOLLISIONAL STRIKE-SLIP FAULTS AND SYNOROGENIC BASINS, CANADIAN CORDILLERA

Author(s):  
G. H. EISBACHER
1979 ◽  
Vol 16 (3) ◽  
pp. 770-791 ◽  
Author(s):  
J. W. H. Monger ◽  
R. A. Price

The present geodynamic pattern of the Canadian Cordillera, the main features of which were probably established in Miocene time, involves a combination of right-hand strike-slip movements on transform faults along the continental margin, and, in the south and extreme north, convergence in subduction zones in which oceanic lithosphere moves beneath the continent, with consequent magmatism along the continental margin. In the southern Canadian Cordillera, geophysical surveys have outlined the subducting slab and the asthenospheric bulge that occurs beneath and behind the magmatic arc. They also show that there is now no root of thickened Precambrian continental crust beneath the tectonically shortened supracrustal strata in the southern parts of the Omineca Crystalline Belt and Rocky Mountain Belt.The Rocky Mountain, Omineca Crystalline, Intermontane, Coast Plutonic, and Insular Belts, the structural and physiographic provinces that dominate the present configuration of the Canadian Cordillera, were established with the initial uplift and the intrusion of granitic rocks in the Omineca Crystalline Belt in Middle and Late Jurassic time and in the Coast Plutonic Complex in Early Cretaceous time, and they dominated patterns of uplift, erosion and deposition through Cretaceous and Paleogene time. Their development may be due to compression with thrust faulting in the eastern Cordillera, and to magmatism that accompanied subduction and to accretion of an exotic terrane, Wrangellia, in the western Cordillera. Major right-lateral strike-slip faulting, which occurred well east of but sub-parallel with the continental margin during Late Cretaceous and Paleogene time, accompanied major tectonic shortening due to thrusting and folding in the Rocky Mountain Belt as well as the main subduction-related (?) magmatism in the Coast Plutonic Complex.The configuration of the western Cordillera prior to late Middle Jurassic time is enigmatic. Late Paleozoic and early Mesozoic volcanogenic strata form a complex collage of volcanic arcs and subduction complexes that was assembled mainly in the Mesozoic. The change in locus of deposition between Upper Triassic and Lower to Middle Jurassic volcanogenic assemblages, and the thrust faulting in the northern Cordillera may record emplacement of another exotic terrane, the Stikine block, in latest Triassic to Middle Jurassic time.The earliest stage in the evolution of the Cordilleran fold belt involved the protracted (1500 to 380 Ma) development of a northeasterly tapering sedimentary wedge that discordantly overlaps Precambrian structures of the cratonic basement. This miogeoclinal wedge may be a continental margin terrace wedge that was prograded into an ocean basin, but it has features that may be more indicative of progradation into a marginal basin in which there was intermittent volcanic activity, than into a stable expanding ocean basin of the Atlantic type.


Geology ◽  
2020 ◽  
Vol 49 (1) ◽  
pp. 101-105
Author(s):  
M.E. McMechan ◽  
K.G. Root ◽  
P.S. Simony ◽  
D.R.M. Pattison

Abstract Cambrian and Upper Devonian to Mississippian strata can be confidently traced westward, without strike-slip offset, from the autochthonous section above North American basement into the southeastern Canadian Cordillera, and are thus “nailed” to the craton. These strata are in turn stratigraphically pinned to older (Mesoproterozoic Belt-Purcell Supergroup, Neoproterozoic Windermere Supergroup, and Ediacaran), intermediate-aged (Ordovician–Silurian), and younger (Permian to Middle Jurassic) strata found only in the mountains, thus linking them to the adjacent autochthonous craton. The overlapping distribution of linking successions, regionally traceable unique stratigraphic horizons in the Belt-Purcell and Windermere Supergroups, and across-strike stratigraphic features show that the entire Cariboo, northern Selkirk, Purcell, and Rocky Mountains are directly tied to the adjacent North American craton without discernible strike-slip or oblique displacement, or substantial purely convergent plate-scale (>400 km) horizontal displacement. They link the entire width of the Belt-Purcell and Windermere basins in the southeastern Canadian Cordillera to the adjacent craton and show that any proposed Cretaceous ribbon continent suture, with its thousands of kilometers of proposed displacement, cannot run through the southeastern Canadian Cordillera.


2005 ◽  
Vol 42 (12) ◽  
pp. 2141-2160 ◽  
Author(s):  
Stefan Kruse ◽  
Paul F Williams

Regionally recognized dextral strike-slip faulting is present in the Monashee complex of the southern Canadian Cordillera but is overprinted and partially obscured by subsequent extension. Eocene brittle faults and fractures within the Thor–Odin culmination of the Monashee complex are divisible into three distinct sets. Initial 340°–010° trending strike-slip faults (set 1) were locally overprinted and reactivated by normal faults with a 325°–020° trend (set 2). A third set of 255°–275° trending fractures (set 3) are interpreted as conjugates to set 1, reactivated as transfer faults to the set 2 normal faults. Large regional faults weather recessively, forming topographic lineaments that transect the Monashee complex. The Victor Creek Fault defines one such lineament. Detailed mapping within the northern Thor–Odin culmination reveals piercement points (fold hinges) on the east side of the fault that are not readily matched on the west side. The minimum displacement required on the Victor Creek Fault to down-drop the fold hinge below the level of exposure on the west side is 1370 m, assuming normal down-to-the-west displacement. The geometry of the fault is consistent with a set 1 dextral strike-slip fault, however. Matching the piercement points in the study area with possible equivalents to the north indicates 55–60 km of dextral strike-slip displacement.


1980 ◽  
Vol 70 (5) ◽  
pp. 1771-1786
Author(s):  
Garry C. Rogers ◽  
Robert M. Ellis ◽  
Henry S. Hasegawa

abstract At 22h37m02s UTC on May 14, 1978, a magnitude (ML) 4.8 earthquake occurred in the Canadian Rockies near McNaughton Lake, the large reservoir behind the Mica Dam in eastern British Columbia. The data suggest it was not a reservoir-induced earthquake. The earthquake was within a seismic array monitoring the reservoir and consequently, the epicenter is well constrained in a northwest-southeast direction. The preferred epicenter is 52.65°N, 118.89°W, slightly east of the Rocky Mountain Trench, with a shallow focal depth of about 10 km. There were no foreshocks but a normal aftershock sequence. The focal mechanism, the first for the eastern Canadian Cordillera, indicates predominantly right-lateral strike-slip faulting along the strike of the mountains with a significant thrust component. The moment is 4 ± 2 × 1023 dyne-cm with a low stress drop (<10 bars). A well-developed Lg phase was recorded to the south of the earthquake. The isoseismals are elongated in a north-south direction and the rate with which intensity attenuates in a southerly direction is comparable to that for eastern North America.


1978 ◽  
Vol 15 (5) ◽  
pp. 823-830 ◽  
Author(s):  
J. W. H. Monger ◽  
T. A. Richards ◽  
I. A. Paterson

The Omineca Crystalline Belt of the Canadian Cordillera is flanked on the west by the Hinterland Belt, characterized by folds and faults that show predominant westward directed tectonic transport. Rocks involved in northern and central British Columbia comprise the Cache Creek Group and, to the west, various Permian, Triassic and Jurassic units. The structures in this belt record three major episodes of deformation. Earliest folds in the Cache Creek Group probably reflect latest Triassic deformation and cannot be related to the Hinterland Belt for they trend obliquely to it. In northern and central British Columbia the Hinterland Belt as a structural entity was produced by probable latest Jurassic or earliest Cretaceous deformation. Major east-dipping thrust and reverse faults, associated locally with folds and schist terranes, bring Cache Creek strata over and against coeval and younger rocks to the west. This belt was later disrupted by strike-slip faults in Late Cretaceous – Early Tertiary time.


2020 ◽  
Vol 3 (2) ◽  
pp. 781-790
Author(s):  
M. Rizwan Akram ◽  
Ali Yesilyurt ◽  
A.Can. Zulfikar ◽  
F. Göktepe

Research on buried gas pipelines (BGPs) has taken an important consideration due to their failures in recent earthquakes. In permanent ground deformation (PGD) hazards, seismic faults are considered as one of the major causes of BGPs failure due to accumulation of impermissible tensile strains. In current research, four steel pipes such as X-42, X-52, X-60, and X-70 grades crossing through strike-slip, normal and reverse seismic faults have been investigated. Firstly, failure of BGPs due to change in soil-pipe parameters have been analyzed. Later, effects of seismic fault parameters such as change in dip angle and angle between pipe and fault plane are evaluated. Additionally, effects due to changing pipe class levels are also examined. The results of current study reveal that BGPs can resist until earthquake moment magnitude of 7.0 but fails above this limit under the assumed geotechnical properties of current study. In addition, strike-slip fault can trigger early damage in BGPs than normal and reverse faults. In the last stage, an early warning system is proposed based on the current procedure. 


1998 ◽  
Author(s):  
Warren J. Nokleberg ◽  
Timothy D. West ◽  
Kenneth M. Dawson ◽  
Vladimir I. Shpikerman ◽  
Thomas K. Bundtzen ◽  
...  

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