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June Lecture: John Armentrout, the Marine Coaledo Formation:

  • Cramer Hall, Portland State University 1721 Southwest Broadway Portland, OR, 97201 United States (map)

The Marine Coaledo Formation: Progress report on an integrated study of an Eocene subtropical shelf-margin delta, Coos Bay, Oregon

The Middle to Late Eocene Coaledo Formation and underlying Beds of Sacchi Beach record a marine history of forearc sedimentation. The sediments aggrade from slope turbidites to shoreface deltaic sandstone encased in deep-water silty mudstone. This talk is a progress report on a multiyear, multidiscipline research program, testing the hypothesis that the Sacchi Beach-Coaledo succession represents a shelf-margin lowstand of sealevel deltaic system. A team of 12 geoscientists is collecting an interdisciplinary database for reassessing the depositional history of the rocks exposed along the Cape Arago, Shore Acres and Sunset Bay State Parks.

John Armentrout

John Armentrout

John Armentrout is a native Oregonian, and graduate of the University of Oregon and the University of Washington. He was OMSI Outdoor Education Director from 1967 to 1970 (including at Camp Hancock). He focused on Petroleum Geology as a Mobil Oil Exploration geologist (1973-2000), Consulting Geologist (2000-2016), and University of Oregon Instructor for Petroleum Geology (2014-2018).