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Mesozoic terranes of the central Cascades; geology of the Hicks Butte Complex, Easton metamorphic suite, Peshastian Formation and Ingalls ophiolite complex
Journal article

Mesozoic terranes of the central Cascades; geology of the Hicks Butte Complex, Easton metamorphic suite, Peshastian Formation and Ingalls ophiolite complex

James H. MacDonald, Joe D. Dragovich, Mark E. Pecha, Glenn T. Thompson, Shanna C. Stingu, Alex D. Maruszczak, Kristy M. Zalud and Scott H. Milliken
Field Guide (Geological Society of America), Vol.49, pp.79-100
01-2017

Abstract

Areal geology Cascade Range Cretaceous Easton metamorphic suite faults field trips guidebook Hicks Butte Complex Ingalls ophiolite complex Jurassic Mesozoic North America North American Cordillera ophiolite complexes Peshastian Formation petrology Puget Lowland road log tectonic elements terranes thrust sheets United States Washington Windy Pass Thrust
This paper reviews the Mesozoic terranes in the central Cascades, south of the Windy Pass thrust and east of the Straight Creek-Fraser River fault, and provides a guide to field locations for these units. These include the Easton Metamorphic Suite, Hicks Butte complex and higher-grade tectonic zone, the Peshastin Formation, and the Ingalls ophiolite complex (also known as the Ingalls terrane). Age data, whole rock and mineral chemistry, and structural data are reviewed. These oceanic- and arcaffinity terranes formed outboard of the North American craton during the Jurassic and accretion likely occurred during the Late Jurassic or Early Cretaceous. They were then dextrally translated north and emplaced in Washington State during the Late Cretaceous. A better understanding of these Mesozoic terranes will more closely constrain the tectonic development of the North American Cordillera.

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