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Title: The western Idaho suture zones meets the central Montana trough: A soft indentee model

Abstract

The western Idaho suture zone is defined by a thin (5--25 km) belt of mylonitic granitoid rocks formed during large-scale, Cretaceous, dextral strike-slip activity. It marks an initial subvertical boundary between accreted oceanic terranes and cratonic North America. Deformation style along the suture zone changes abruptly from transpressions on the southern segment, to west-vergent thrusting on the northern segment, the change occurring near Slate Ck. The northern segment appears to be a structural and metamorphic culmination-the Clearwater culmination-that acts as the mylonitic root-zone of the Rapid River thrust, which splays off to the SW. The northern and southern extents of the Clearwater culmination coincide with the north and south boundaries of the Central Montana Trough (CMT), an east-west trough containing thick packages of Proterozoic through Mesozoic strata. The CMT has been interpreted as an aulacogen, and as such must have extended to the western edge of N. America after Proterozoic rifting. The change in structural style from pure-shear dominated dextral transpression south of Slate Ck. to west-directed thrusting north of Slate Ck. is likely due to the strong rheologic contrast caused by the intersection of the western Idaho suture zone and the CMT. The CMT acts as a soft-indented', focusingmore » the collisional deformation of the Seven Devils/Wallowa terrain eastward into the unusually thick Proterozoic through Mesozoic rocks of the CMT.« less

Authors:
 [1]
  1. Univ. of Minnesota, Minneapolis, MN (United States). Dept. of Geology and Geophysics
Publication Date:
OSTI Identifier:
5020252
Report Number(s):
CONF-9305259-
Journal ID: ISSN 0016-7592; CODEN: GAAPBC
Resource Type:
Conference
Journal Name:
Geological Society of America, Abstracts with Programs; (United States)
Additional Journal Information:
Journal Volume: 25:5; Conference: 89. annual meeting of the Cordilleran Section and the 46th annual meeting of the Rocky Mountain Section of the Geological Society of America (GSA), Reno, NV (United States), 19-21 May 1993; Journal ID: ISSN 0016-7592
Country of Publication:
United States
Language:
English
Subject:
58 GEOSCIENCES; GEOLOGIC FAULTS; GEOLOGY; GEOLOGIC STRUCTURES; IDAHO; MONTANA; CRETACEOUS PERIOD; DEFORMATION; GEOLOGIC MODELS; GRANITES; OCEANIC CRUST; PLATE TECTONICS; DEVELOPED COUNTRIES; EARTH CRUST; GEOLOGIC AGES; GEOLOGIC FRACTURES; IGNEOUS ROCKS; MESOZOIC ERA; NORTH AMERICA; PLUTONIC ROCKS; ROCKS; TECTONICS; USA; 580000* - Geosciences

Citation Formats

Strayer, L M. The western Idaho suture zones meets the central Montana trough: A soft indentee model. United States: N. p., 1993. Web.
Strayer, L M. The western Idaho suture zones meets the central Montana trough: A soft indentee model. United States.
Strayer, L M. Thu . "The western Idaho suture zones meets the central Montana trough: A soft indentee model". United States.
@article{osti_5020252,
title = {The western Idaho suture zones meets the central Montana trough: A soft indentee model},
author = {Strayer, L M},
abstractNote = {The western Idaho suture zone is defined by a thin (5--25 km) belt of mylonitic granitoid rocks formed during large-scale, Cretaceous, dextral strike-slip activity. It marks an initial subvertical boundary between accreted oceanic terranes and cratonic North America. Deformation style along the suture zone changes abruptly from transpressions on the southern segment, to west-vergent thrusting on the northern segment, the change occurring near Slate Ck. The northern segment appears to be a structural and metamorphic culmination-the Clearwater culmination-that acts as the mylonitic root-zone of the Rapid River thrust, which splays off to the SW. The northern and southern extents of the Clearwater culmination coincide with the north and south boundaries of the Central Montana Trough (CMT), an east-west trough containing thick packages of Proterozoic through Mesozoic strata. The CMT has been interpreted as an aulacogen, and as such must have extended to the western edge of N. America after Proterozoic rifting. The change in structural style from pure-shear dominated dextral transpression south of Slate Ck. to west-directed thrusting north of Slate Ck. is likely due to the strong rheologic contrast caused by the intersection of the western Idaho suture zone and the CMT. The CMT acts as a soft-indented', focusing the collisional deformation of the Seven Devils/Wallowa terrain eastward into the unusually thick Proterozoic through Mesozoic rocks of the CMT.},
doi = {},
url = {https://www.osti.gov/biblio/5020252}, journal = {Geological Society of America, Abstracts with Programs; (United States)},
issn = {0016-7592},
number = ,
volume = 25:5,
place = {United States},
year = {1993},
month = {4}
}

Conference:
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