Thesis
Tephrochronology of mid-Miocene Clarkia Lake sedimentary deposits
Washington State University
Master of Science (MS), Washington State University
2017
Handle:
https://hdl.handle.net/2376/102717
Abstract
Mid-Miocene Clarkia Lake developed when a Priest Rapids Member flow of the Columbia River Basalt Group Wanapum Formation blocked the ancestral St. Maries River, causing the water to back up into a large water body. The deep, anoxic lake bottom conditions, as well as the apparently rapid deposition of lake sediments, provided excellent preservation for fallen vegetation and reworked distal ash deposits; Consequently twelve distinct ash strata have been identified within ~34m of lacustrine sediment. This thesis presents the tephrostratigraphy of the southern end of the lake. Chemical signatures of ashes found within the lake match those of the early Yellowstone Hotspot, the ancestral Cascades, and other high-silica rhyolite sources with unknown origins. Clarkia Lake ashes have been successfully correlated to 1) The Eastern Oregon Bully Creek Formation of ~15.9 Ma (ages of Nash and Perkins, 2012 recalculated to FCS=28.201 Ma); 2) The Northern Nevada Santa Rosa-Calico Cold Springs Tuff of ~15.9 Ma (ages of Brueseke and Hart, 2008 recalculated to FCS=28.201 Ma); 3) Several Buffalo Canyon Formation ashes of ~15.6 and 15.7 Ma; 4) Several Española Basin ashes including two of Cold Springs Tuff chemistry, as well as White Ashes 3 and 4 of ~15.7 and 15.5 Ma, respectively (ages of Koning et al., 2007, recalculated to FCS=28.201Ma). These correlations constrain the age of Clarkia Lake to ~15.5-16.0 Ma, affirming that the majority of Columbia River Basalt volcanism erupted before 15.5 Ma. In addition, chemical correlations between Clarkia Lake sedimentary deposit sites P33 and P37 have allowed for the complete construction of a Clarkia Lake sedimentary deposit tephrostratigraphic column.
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Details
- Title
- Tephrochronology of mid-Miocene Clarkia Lake sedimentary deposits
- Creators
- Cassie S. Geraghty
- Contributors
- John A. Wolff (Degree Supervisor)
- Awarding Institution
- Washington State University
- Academic Unit
- Environment, School of the (CAHNRS)
- Theses and Dissertations
- Master of Science (MS), Washington State University
- Publisher
- Washington State University; [Pullman, Washington] :
- Identifiers
- 99900525136001842
- Language
- English
- Resource Type
- Thesis