Thesis
The stable isotopic composition of authigenic and pedogenic minerals from paleosols in Eastern Washington as makers for climatic change in response to Cascade Range barriers
Washington State University
Master of Science (MS), Washington State University
2003
Handle:
https://hdl.handle.net/2376/133
Abstract
The Cascade Range now forms an extensive topographic and climatic boundary in the Pacific Northwest. In Washington, a mild and humid climate predominates west of the range, where greater than approximately 1800 mm/year of rainfalls; a cooler and drier climate prevails to east of the range due to a massive orographic rain shadow. Distinct pedogenesis between forest soils on the west and desert and grassland soils on the east is obviously associated with the disparate vegetation on each side. Numerous geological and paleofloral studies have argued that a late Cenozoic climate change in eastern Washington from a sub-tropical to a semi-arid/desert climate regime depends on whether the topography of the Washington Cascade Range was prominent, or subdued. The d18O values of authigenic smectites that crystallized in equilibrium with meteoric water were collected from a series of stratigraphic sections in eastern Washington. There strata accumulated between late Miocene time to present record a ~3.2‰ decrease in the d18O values of authigenic smectites between 5–11 Ma; this result suggests d18O values in meteoric water varied due to significant surface uplift of the Washington Cascade Range. The Washington Cascades became a massive orographic barrier to Pacific-derived precipitation during late Miocene time, and the corresponding regional rain shadow region in eastern Washington was developed. The quantitative relationship between elevation change and isotopic depletion of precipitation over mountain belts (isotopic lapse rate) demonstrates the paleorelief of the Washington Cascade Range between late Miocene time and present is approximately 1600 m. This significant surface uplift episode examined by the oxygen isotopic evidence from authigenic clay minerals is supported by the timing of the uplift of the Washington Cascades as determined by apatite and zircon (U-Th)/He and apatite fission-track ages (Reiners et al., 2002).
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Details
- Title
- The stable isotopic composition of authigenic and pedogenic minerals from paleosols in Eastern Washington as makers for climatic change in response to Cascade Range barriers
- Creators
- Akinori Takeuchi
- Contributors
- Peter B. Larson (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, Wash. :
- Identifiers
- 99900525055501842
- Language
- English
- Resource Type
- Thesis