Evolution of a Permo-Triassic sedimentary melange, Grindstone terrane, east-central Oregon
Links
- More information: Publisher Index Page (via DOI)
- Download citation as: RIS | Dublin Core
Abstract
The Grindstone terrane in east-central Oregon is one of the few areas in western North America where large blocks of unmetamorphosed Devonian, Mississippian, and Permian limestones are inter mixed with Permian and Lower Triassic radiolarian chert and Pennsylvanian?, Permian, and Triassic volcaniclastic rocks. Although originally described as parts of a coherent succession, we interpret the Grindstone rocks to be a sedimentary mélange composed of Paleozoic limestone slide and slump blocks that became detached from a carbonate shelf fringing a volcanic knoll or edifice in Late Permian to Middle Triassic time and were intermixed with Permian and Triassic slope to basinal clastic and volcaniclastic rocks in a forearc basin setting. Paleogeographic affinities of the Grindstone limestone faunas and volcaniclastic debris in the limestone and clastic rocks all indicate deposition in proximity to an island-arc system near the North American craton. The Grindstone terrane deposits are unconformably overlain by Upper Triassic to Middle Jurassic sequences of the Izee terrane. Although lithologic and faunal differences indicate that the Grindstone and Izee terranes together represent a tectonic block separate from the adjacent Baker terrane, all three terranes were juxtaposed by Late Triassic or Early Jurassic time.
Study Area
| Publication type | Article |
|---|---|
| Publication Subtype | Journal Article |
| Title | Evolution of a Permo-Triassic sedimentary melange, Grindstone terrane, east-central Oregon |
| Series title | Geological Society of America Bulletin |
| DOI | 10.1130/0016-7606(1991)103<1280:EOAPTS>2.3.CO;2 |
| Volume | 103 |
| Issue | 10 |
| Year Published | 1991 |
| Language | English |
| Publisher | Geological Society of America |
| Description | 17 p. |
| First page | 1280 |
| Last page | 1296 |
| Country | United States |
| State | Oregon |
| Google Analytic Metrics | Metrics page |