Eruption-controlled epiclastic sedimentation in a Devonian trench-slope basin: Evidence from sandstone petrofacies, Klamath Mountains, California
Journal Article
·
· Journal of Sedimentary Research - Section A; (United States)
OSTI ID:7233617
- Univ. of Nevada, Las Vegas, NV (United States). Dept. of Geoscience
The Devonian Gazelle Formation comprises sparsely fossiliferous shale, siltstone, siliceous mudstone, volcaniclastic sandstone, and conglomerate whose cumulative thickness is at least 1.25 km. Two end-member sand compositions combined locally to form a third mixed'' petrofacies. The volcaniclastic petrofacies was derived from an undissected magmatic arc, whereas the chert-mudrock petrofacies reflects derivation from melange of the underlying accretionary prism. The stratigraphically restricted mixed petrofacies is compositionally discrete and records thorough mixing of these two compositional end members. Data from sandstone petrography are consistent with independent geologic evidence indicating that the Gazelle Formation represents the fill of a Devonian trench-slope basin that formed above an east-dipping subduction zone. The authors interpretation of the Balaklala Rhyolite as the source of the volcaniclastic petrofacies requires proximity of the Yreka and Eastern Klamath terranes during the Early Devonian, and indicates that the eastern Klamath province has behaved as a single crustal block (sensu lato) ever since. Field study and petrographic analysis indicate that the delivery of coarse terrigenous detritus to the basin was controlled principally by episodic eruptions of rhyolitic tephra in the arc source and also by one discernible episode of change in relative sea level. This study indicates that caution must be used when invoking changes in relative sea level to explain the stratigraphic distribution of epiclastic turbidites in island-arc settings.
- OSTI ID:
- 7233617
- Journal Information:
- Journal of Sedimentary Research - Section A; (United States), Journal Name: Journal of Sedimentary Research - Section A; (United States) Vol. A64:2; ISSN XZ288H
- Country of Publication:
- United States
- Language:
- English
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