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Porath, D.A., 2008

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Porath, D.A., 2008, Stratigraphy, paleontology, and paleogeography of the middle Pleistocene Tugidak Formation, Trinity Islands, Alaska: Boca Raton, Florida, Florida Atlantic University, M.S. thesis, 286 p.


Tugidak Island, the northernmost of the Trinity Islands off the SW coast of Kodiak Island, is the stratotype of the Tugidak Formation. The continuous section of the Tugidak Formation crops out in the sea cliffs along the northern and southwestern parts of the island and is the most complete section in the Trinity Islands. The exposed section of the Tugidak Formation is composed of 1,395 m of glacial marine diamictite containing abundant molluscan fossils. Seismic profiles and well data indicate a regionally extensive deposition of the Tugidak Formation across the Kodiak Shelf. Paleomagnetic sampling and diatom analysis in this work has further refined the age of the Tugidak Formation as early-middle Pleistocene. By attempting a reconstruction of the tectonic evolution and through faunal identification, inferences are made about the paleobiogeography, paleoclimate, and timing of sedimentary depositional cycles, around Tugidak Island.

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