The Umpqua Group of southwestern Oregon preserves one of the most complete sedimentary records of the early Eocene collision between the Siletz terrane and North America. My research investigates how tectonic loading, basin subsidence, sediment supply, and evolving source-area topography controlled the development of the Umpqua Basin during its transition from syn-collisional to post-collisional conditions.
The study integrates geologic mapping, LiDAR analysis, measured stratigraphic sections, geologic cross sections, detrital-zircon U-Pb geochronology, biostratigraphic data, and existing well and seismic information. Preliminary results indicate that the basin developed as an asymmetric syn-collisional flexural foredeep adjacent to the Klamath Mountains. The Umpqua Group reaches approximately 3 km in thickness in the southeastern basin and thins northwestward across the Umpqua Arch. Repeated transitions from fluvial– deltaic to marine environments suggest episodes during which tectonically driven subsidence outpaced sediment supply.
A regional unconformity at the base of the Camas Valley Formation records the transition to post-collisional sedimentation during initiation of the Cascadia subduction zone at approximately 50–47 Ma. By refining the basin’s chronology, geometry, and depositional history, this project evaluates how terrane collision and subsequent tectonic reorganization shaped early Eocene sedimentary systems in western Oregon.
This research is part of the ESCAPE project, a broader collaborative effort to reconstruct how landscapes, river systems, sedimentary basins, and sediment-routing networks responded to the collision of Siletzia and the subsequent initiation of Cascadia subduction.
The study integrates geologic mapping, LiDAR analysis, measured stratigraphic sections, geologic cross sections, detrital-zircon U-Pb geochronology, biostratigraphic data, and existing well and seismic information. Preliminary results indicate that the basin developed as an asymmetric syn-collisional flexural foredeep adjacent to the Klamath Mountains. The Umpqua Group reaches approximately 3 km in thickness in the southeastern basin and thins northwestward across the Umpqua Arch. Repeated transitions from fluvial– deltaic to marine environments suggest episodes during which tectonically driven subsidence outpaced sediment supply.
A regional unconformity at the base of the Camas Valley Formation records the transition to post-collisional sedimentation during initiation of the Cascadia subduction zone at approximately 50–47 Ma. By refining the basin’s chronology, geometry, and depositional history, this project evaluates how terrane collision and subsequent tectonic reorganization shaped early Eocene sedimentary systems in western Oregon.
This research is part of the ESCAPE project, a broader collaborative effort to reconstruct how landscapes, river systems, sedimentary basins, and sediment-routing networks responded to the collision of Siletzia and the subsequent initiation of Cascadia subduction.
