Coastal lakes along the Pacific Northwest provide valuable sedimentary archives for reconstructing Holocene paleoenvironmental variability, coastal landscape evolution, and extreme events associated with the Cascadia Subduction Zone. Woahink Lake, a dune-dammed freshwater lake situated approximately 3.2 km from the Pacific Ocean in the Oregon Coast Range, preserves a sedimentary sequence spanning the last ~7,500 years. Previous paleolimnological investigations revealed a complex environmental history characterized by a transition from marine-estuarine to freshwater conditions between approximately 7.5 and 5.4 ka, followed by relatively stable lacustrine sedimentation interrupted by episodic disturbances potentially associated with regional seismic activity. Building upon this existing stratigraphic and chronological framework, the proposed study aims to refine the paleoenvironmental reconstruction of Woahink Lake through an integrated sedimentological and geochemical investigation. High-resolution X-ray fluorescence (XRF) elemental analyses will provide insights into changes in detrital sediment supply, sediment provenance, mineralogical composition, and depositional conditions. Total organic carbon (TOC) and total inorganic carbon (TIC) measurements will be employed to assess changes in organic matter accumulation, carbonate formation, and lake productivity, while grain-size distributions and end-member modelling will help identify variations in sediment transport mechanisms, hydrodynamic energy, and depositional environments. Particular attention will be directed toward identifying abrupt sedimentary changes and event deposits potentially associated with regional earthquakes, coastal flooding, and tsunami inundation. Complementary organic geochemical investigations, including lipid biomarkers such as n-alkanes, sterols, and selected marine- and terrestrial-derived molecular compounds, will be explored to distinguish sedimentary organic matter sources and identify potential evidence of marine incursions and sediment reworking. The integration of these proxies with the existing radiocarbon chronology will allow the reassessment of previously identified disturbance horizons, particularly those potentially associated with major Cascadia earthquakes and tsunami events. Ultimately, this research seeks to develop a refined reconstruction of Holocene coastal environmental evolution and evaluate the potential of coastal lacustrine sediments as archives of extreme events along the Cascadia Subduction Zone. 

This project is carried out in cooperation with the University of Oregon, USA.