Portland State University. Department of Geology
Marvin H. Beeson
Date of Publication
Master of Science (M.S.) in Geology
Stratigraphic geology, Geology -- Oregon -- Keasey Formation, Geology -- Oregon -- Cowlitz Formation, Gas wells -- Oregon
1 online resource (109 p.)
Lithological, geophysical, paleontological and geochemical methods were used in order to define the contact relationship between the Keasey and the Cowlitz formations in northwestern Oregon. Drill cuttings from six wells located in Columbia County were analyzed by the Instrumental Neutron Activation Analysis (INAA) method. The concentrations of K, Th, Rb and Sc/Co ratio in the samples established four different groups: 1) High K, Rb, and TH, with low Sc/Co ratio typical of Cowlitz sediments. 2) Low K, Th and Rb and high Sc/Co ratio, more characteristics of the Keasey Formation. 3) Very low concentrations of Rb and high Sc, which is indicative of basaltic volcanism. 4) vertically varying K, Th and Rb concentrations. The provenance of group four is uncertain, but it may represent reworked sediments or the interfingering of the Keasey and the Cowlitz formations. Plots of these elements vs. depth define the geochemical contacts between the formations.
Lira, Olga Berenice, "Subsurface and geochemical stratigraphy of northwestern Oregon" (1990). Dissertations and Theses. Paper 4314.