First Advisor

Gilbert T. Benson

Date of Publication

1982

Document Type

Thesis

Degree Name

Master of Science (M.S.) in Geology

Department

Earth Science

Language

English

Subjects

Areal Geology, Oregon, Pacific Coast

DOI

10.15760/etd.3247

Physical Description

1 online resource (86 p.)

Abstract

The Floras Creek area, east of the town of Langlois, near the southwest Oregon coast, includes Colebrooke Schist (a klippe of metamorphosed pelitic sediments of Jurassic age), Jurassic Otter Point Formation (a melange complex), and lower the middle Eocene Roseburg and Lookingglass Formations, part of a sandstone-shale sequence occurring more extensively in other areas. The Colebrooke Schist occurs in the south-central part of the area, bounded on the Otter Point and Roseburg. The Lookingglass is exposed as a small (1.5 sq. km) block in the north-north-west part of the area. Two major structural trends are found in the Floras Creek area; an older Mesozoic east-west normal fault trend which is truncated by younger serpentinitefilled, north-south shear zones. The younger fault trend was active into the Tertiary as the faults cut the Eocene. Detrital modal analyses of sandstones suggest that the Otter Point is related to the coeval Dothan Formation of the interior Klamath Mountains, in the same way that the Franciscan is related to the Great Valley sequence in California. The detrital modal analysis indicates that the Otter Point is trench-slope deposited sediments as is the Franciscan and the Dothan is forearc basin deposits similar to the Great Valley.

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Comments

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This thesis includes supplemental content

Persistent Identifier

http://archives.pdx.edu/ds/psu/18694

Additional Files
geological-map-smaller.pdf (482 kB)
Geologic Map of the Floras Creek Area
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