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Mesozoic tectonics west of the accretionary boundary in west-central Idaho; a road log along U.S. Highway 95 between Moscow and New Meadows, Idaho

Keegan L. Schmidt, Keith D. Gray, Reed S. Lewis, Cody J. Steven and Vince H. Isakson
Mesozoic tectonics west of the accretionary boundary in west-central Idaho; a road log along U.S. Highway 95 between Moscow and New Meadows, Idaho (in Exploring the geology of the inland Northwest, Reed S. Lewis (editor) and Keegan L. Schmidt (editor))
Field Guide (Geological Society of America) (2016) 41: 175-209

Abstract

The late Mesozoic accretionary boundary in west-central Idaho has played a critical role in tectonic models proposed for the northwestern U.S. Cordillera. From west-to-east, major elements include the Permian to Jurassic Wallowa island-arc terrane, a poorly understood transition zone consisting of the Riggins Group assemblage and deformation belt along the west side of the island arc-continent boundary, Late Jurassic to Cretaceous arc-continent boundary, and Precambrian North American margin intruded by the Cretaceous-Paleogene Idaho batholith. We focus on the transition zone in the area between White Bird and Riggins, Idaho, which includes a contractional belt in variously deformed and metamorphosed rocks of island-arc affinity. We propose that the rocks of the entire transition zone, including those originally defined as the Riggins Group, are likely of Wallowa terrane origin and/or related basinal assemblages. Ultramafic rocks in the transition zone are possibly related to a Jurassic or Cretaceous basinal assemblage that includes the Squaw Creek Schist of the Riggins Group. Our recent work addresses the kinematic history of structures in the contractional belt. The belt was reactivated in the Neogene to accommodate mostly brittle normal faulting that strongly influenced preservation of the Miocene Columbia River Basalt Group at this location along the eastern margin of the flood basalt province. This field guide provides a road log for examining the geology between Moscow and New Meadows, Idaho, along U.S. Highway 95.


ISSN: 2333-0937
EISSN: 2333-0945
Serial Title: Field Guide (Geological Society of America)
Serial Volume: 41
Title: Mesozoic tectonics west of the accretionary boundary in west-central Idaho; a road log along U.S. Highway 95 between Moscow and New Meadows, Idaho
Title: Exploring the geology of the inland Northwest
Author(s): Schmidt, Keegan L.Gray, Keith D.Lewis, Reed S.Steven, Cody J.Isakson, Vince H.
Author(s): Lewis, Reed S.editor
Author(s): Schmidt, Keegan L.editor
Affiliation: Lewis-Clark State College, Division of Natural Sciences, Lewiston, ID, United States
Affiliation: University of Idaho, Idaho Geological Survey, Moscow, ID, United States
Pages: 175-209
Published: 2016
Text Language: English
Publisher: Geological Society of America, Boulder, CO, United States
References: 175
Accession Number: 2016-083399
Categories: Structural geology
Document Type: Serial
Bibliographic Level: Analytic
Illustration Description: illus. incl. sects., geol. sketch maps
N45°00'00" - N47°00'00", W117°15'00" - W115°00'00"
Secondary Affiliation: Wichita State University, USA, United StatesUniversity of Idaho, USA, United StatesBoise State University, USA, United States
Country of Publication: United States
Secondary Affiliation: GeoRef, Copyright 2017, American Geosciences Institute. Reference includes data supplied by the Geological Society of America, Boulder, CO, United States
Update Code: 201640
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