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Magnetic Stratigraphy and Tectonic Rotation of the Eocene Tyee Formation, Southwestern Oregon
| Content Provider | Semantic Scholar |
|---|---|
| Author | Prothero, Donald Hoffman, Jonathan M. Ryu, In-Chang |
| Copyright Year | 2011 |
| Abstract | The Tyee Formation consists of a long sequence of volcaniclastic-rich turbidite sandstones and tﾬeous siltstones about 2000 m (6000 feet) thick exposed in roadcuts and stream beds in southwestern Oregon. Sampling was conducted along the best continuous traverse through the section along roadcuts on Oregon Highway 38 west of Drain, and east of Elkton, Oregon. Most samples yielded directions during the low-temperature thermal demagnetization that are held in magnetite and passed a reversal test. Petrographic examination of the rocks showed abundant magnetite with no significant hematite. Our results gave a tectonic rotation of 65° ± 15°, consistent with earlier studies by Simpson and Cox (1977) on the Tyee-White Tail Ridge formations, and with all other clockwise rotations reported across the entire Cenozoic sequence of the Oregon-Washington Coast Ranges. Based on the presence of Zone CP12a nannofossils, Domengine Stage mollusks, and Ulatisian Stage benthic foraminifera, the magnetic stratigraphy of the Highway 38 section gives a reversed-normal-reversed polarity pattern that best correlates with the end of Chron C22r, all of Chron C22n, and the earliest part of Chron C21r (48.5-50 Ma), or latest Early Eocene and earliest Middle Eocene. |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | http://www.donaldprothero.com/files/92368738.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
