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DEPOSITIONAL RELATIONS OF UMPQUA AND TYEE FORMATIONS (EOCENE), SOUTHWESTERN OREGON.

American Association of Petroleum Geologists Bulletin

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Abstract

The Umpqua Formation (as herein restricted) consists of as much as 10,000 ft of mudstone, sandstone, and conglomerate of nonmarine to deep marine origin. A basaltic basement that underlies the sedimentary rocks in most of the area and was formerly included in the Umpqua is herein considered a separate unit and assigned to the Siletz River Volcanics. A proposal to subdivide the Umpqua into three unconformity-bounded formations in the area west of Roseburg, Oregon, is not recognized in this report because of questionable correlations and limited extent of some units. The Tyee Formation, which conformably overlies the Umpqua, is a predominantly sandstone unit about 6,000 ft thick, deposited in environments ranging from shallow marine and nonmarine deltaic on the south, to slope and deep marine basinal to the north. Deposition across the Umpqua-Tyee boundary contact represents a change in tectonic setting. Refs.

Additional Publication Details

Publication type:
Article
Publication Subtype:
Journal Article
Title:
DEPOSITIONAL RELATIONS OF UMPQUA AND TYEE FORMATIONS (EOCENE), SOUTHWESTERN OREGON.
Series title:
American Association of Petroleum Geologists Bulletin
Volume
69
Issue:
8
Year Published:
1985
Language:
English
Larger Work Type:
Article
Larger Work Subtype:
Journal Article
First page:
1217
Last page:
1229
Number of Pages:
13