Three modes of isograd formation in the northern Monashee Complex of the Canadian Cordillera

2018 ◽  
Vol 478 (1) ◽  
pp. 373-388 ◽  
Author(s):  
Félix Gervais
Keyword(s):  
Canadian Cordillera ◽  
Monashee Complex

Northeastward extrusion and extensional exhumation of crystalline rocks of the Monashee complex, southeastern Canadian Cordillera

2000 ◽  
Vol 22 (5) ◽  
pp. 603-625 ◽  
Author(s):  
Dennis H. Johnston ◽  
Paul F. Williams ◽  
Richard L. Brown ◽  
James L. Crowley ◽  
Sharon D. Carr
Keyword(s):  
Crystalline Rocks ◽  
Canadian Cordillera ◽  
Monashee Complex

scholarly journals Assessing Inheritance of Zircon and Monazite in Granitic Rocks from the Monashee Complex, Canadian Cordillera

2008 ◽  
Vol 49 (11) ◽  
pp. 1915-1929 ◽  
Author(s):  
J. L. Crowley ◽  
R. L. Brown ◽  
F. Gervais ◽  
H. D. Gibson
Keyword(s):  
Granitic Rocks ◽  
Canadian Cordillera ◽  
Monashee Complex

U–Pb geochronologic constraints on the cover sequence of the Monashee complex, Canadian Cordillera: Paleoproterozoic deposition on basement

1997 ◽  
Vol 34 (7) ◽  
pp. 1008-1022 ◽  
Author(s):  
James L. Crowley
Keyword(s):  
Hanging Wall ◽  
Crystalline Basement ◽  
Detrital Zircons ◽  
Canadian Cordillera ◽  
Metasedimentary Rocks ◽  
Monashee Complex ◽  
Minimum Age ◽  
Age Constraints ◽  
Unconformable Contact ◽  
Different Parts

The cover sequence in the Monashee complex is a platformal metasedimentary succession that occupies a nearly unique position in the Canadian Cordillera due to its unconformable contact with exposed crystalline basement. Zircon U–Pb data and field observations show that the lower part of the sequence contains Paleoproterozoic rocks, the oldest known metasedimentary rocks in the Cordilleran miogeocline, and the upper part of the sequence is Mesoproterozoic or younger. Maximum age constraints on the lower part are provided by 1.99 Ga detrital zircons from the basal unit and a 1862 ± 1 Ma orthogneiss upon which it was presumably deposited. Minimum age constraints are provided by rocks that intruded into the lower part: 1852 ± 4 Ma pegmatite, 1762 ± 6 Ma leucogranite, and 724 ± 5 Ma syenitic gneiss. The upper part of the sequence must be considerably younger than the lower part because it contains a detrital zircon dated at ~1.21 Ga. Other detrital zircons, dated at Neoarchean (2.95–2.86 Ga) and Paleoproterozoic (1.85–1.81, 1.75 Ga), suggest a source in the western Canadian Shield. These ages constrain the thickness of Mesoproterozoic and Neoproterozoic metasedimentary rocks in the cover sequence to be < 2 km. Combining these ages with previously interpreted Paleozoic deposition ages for the middle and upper parts of the sequence constrains the thickness to be <0.2 km, considerably less than that of coeval rocks above the Monashee complex in the hanging wall of the Monashee décollement. Such a contrast suggests that deposition above and below the décollement occurred in different parts of the Cordilleran miogeocline.

Brittle faulting in the Thor–Odin culmination, Monashee complex, southern Canadian Cordillera: constraints on geometry and kinematics

2005 ◽  
Vol 42 (12) ◽  
pp. 2141-2160 ◽  
Author(s):  
Stefan Kruse ◽  
Paul F Williams
Keyword(s):  
Strike Slip ◽  
Normal Faults ◽  
Canadian Cordillera ◽  
The West ◽  
West Side ◽  
The North ◽  
Monashee Complex ◽  
Dextral Strike Slip Fault ◽  
Brittle Faulting ◽  
Dextral Strike Slip

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.

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