Kinematics and timing of exhumation of metamorphic core complexes along the Lewis and Clark fault zone, northern Rocky Mountains, USA

2007 ◽  
pp. 207-232 ◽  
Author(s):  
David A. Foster ◽  
P. Ted Doughty ◽  
Thomas J. Kalakay ◽  
C. Mark Fanning ◽  
Samuel Coyner ◽  
...  
Keyword(s):  
Fault Zone ◽  
Rocky Mountains ◽  
Northern Rocky Mountains ◽  
Metamorphic Core Complexes ◽  
Clark Fault ◽  
Lewis And Clark ◽  
Metamorphic Core

scholarly journals Whole-lithosphere shear during oblique rifting

Geology ◽  
2021 ◽  
Author(s):  
Brandon M. Lutz ◽  
Gary J. Axen ◽  
Jolante W. van Wijk ◽  
Fred M. Phillips
Keyword(s):  
Shear Zone ◽  
Fault Zone ◽  
Shear Zones ◽  
Death Valley ◽  
Necessary Condition ◽  
Middle Crust ◽  
Metamorphic Core Complexes ◽  
Dextral Shear ◽  
Depth Gradients ◽  
Metamorphic Core

Processes controlling the formation of continental whole-lithosphere shear zones are debated, but their existence requires that the lithosphere is mechanically coupled from base to top. We document the formation of a dextral, whole-lithosphere shear zone in the Death Valley region (DVR), southwest United States. Dextral deflections of depth gradients in the lithosphere-asthenosphere boundary and Moho are stacked vertically, defining a 20–50-km-wide, lower lithospheric shear zone with ~60 km of shear. These deflections underlie an upper-crustal fault zone that accrued ~60 km of dextral slip since ca. 8–7 Ma, when we infer that whole-lithosphere shear began. This dextral offset is less than net dextral offset on the upper-crustal fault zone (~90 km, ca. 13–0 Ma) and total upper-crustal extension (~250 km, ca. 16–0 Ma). We show that, before ca. 8–7 Ma, weak middle crust decoupled upper-crustal deformation from deformation in the lower crust and mantle lithosphere. Between 16 and 7 Ma, detachment slip thinned, uplifted, cooled, and thus strengthened the middle crust, which is exposed in metamorphic core complexes collocated with the whole-lithosphere shear zone. Midcrustal strengthening coupled the layered lithosphere vertically and therefore enabled whole-lithosphere dextral shear. Where thick crust exists (as in pre–16 Ma DVR), midcrustal strengthening is probably a necessary condition for whole-lithosphere shear.

Spatial databases for the geology of the northern Rocky Mountains - Idaho, Montana, and Washington

2005 ◽  
Author(s):  
Michael L. Zientek ◽  
Pamela D. Derkey ◽  
Robert J. Miller ◽  
J. Douglas Causey ◽  
Arthur A. Bookstrom ◽  
...  
Keyword(s):  
Rocky Mountains ◽  
Spatial Databases ◽  
Northern Rocky Mountains

Guide to geophysical data for the northern Rocky Mountains and adjacent areas, Idaho, Montana, Washington, Oregon, and Wyoming

2004 ◽  
Author(s):  
Edward A. Mankinen ◽  
Thomas G. Hildenbrand ◽  
Michael L. Zientek ◽  
Stephen E. Box ◽  
Arthur A. Bookstrom ◽  
...  
Keyword(s):  
Rocky Mountains ◽  
Geophysical Data ◽  
Northern Rocky Mountains
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