Portland DDU Feasibility Study: The Spatial and Temporal Evolution of the Portland and Tualatin Basins, Oregon, USA
The Portland and Tualatin basins are part of the Puget-Willamette Lowland in the Cascadia forearc of Oregon and Washington. The Coast Range to the west has undergone Paleogene transtension and Neogene transpression, which is reflected in basin stratigraphy. To better understand the tectonic evolution of the region, Darby Scanlon modeled three key stratigraphic horizons and their associated depocenters (areas of maximum sediment accumulation) through space and time using well log, seismic, outcrop, aeromagnetic, and gravity data. Three isochore maps were created to constrain the location of Portland and Tualatin basin depocenters during 1) Pleistocene to mid-Miocene (0-15 Ma), 2) eruption of the Columbia River Basalt Group (CRBG, 15.5-16.5 Ma), and 3) MidMiocene to late Eocene time (~17-35 Ma).
Results show that the two basins each have distinct mid-Miocene to Pleistocene depocenters. The depth to CRBG in the Portland basin reaches a maximum of ~1,640 ft, 160 ft deeper than the Tualatin basin. Although the Portland basin is separated from the Tualatin basin by the Portland Hills, inversion of gravity data suggests that the two were connected as one continuous basin prior to CRBG deposition. Local thickening of CRBG flows over a gravity low coincident with the Portland Hills suggests that Neogene transpression in the forearc reactivated the SylvanOatfield and Portland Hills faults as high angle reverse faults. This structural inversion separated the once continuous Portland and Tualatin basins in the mid-late Miocene. A change in the stress regime at that time marks the transition from Paleogene forearc extension to deformation dominated by north-south shortening due to collision of the forearc against the Canadian Coast Mountains. An eastward shift of the forearc basin ii depocenter over the Neogene likely reflects uplift of the Coast Range to the west. A change in regional stress in the mid to late-Miocene, along with uplift of the Oregon Coast Range, caused a 10-fold decrease in sediment accumulation rates across the Portland and Tualatin basins. Transpressional oblique-slip faulting continues to deform the region as the forearc undergoes clockwise rotation and collides with the rigid Canadian Coast Mountains to the north.
Citation Formats
TY - DATA
AB - The Portland and Tualatin basins are part of the Puget-Willamette Lowland in the Cascadia forearc of Oregon and Washington. The Coast Range to the west has undergone Paleogene transtension and Neogene transpression, which is reflected in basin stratigraphy. To better understand the tectonic evolution of the region, Darby Scanlon modeled three key stratigraphic horizons and their associated depocenters (areas of maximum sediment accumulation) through space and time using well log, seismic, outcrop, aeromagnetic, and gravity data. Three isochore maps were created to constrain the location of Portland and Tualatin basin depocenters during 1) Pleistocene to mid-Miocene (0-15 Ma), 2) eruption of the Columbia River Basalt Group (CRBG, 15.5-16.5 Ma), and 3) MidMiocene to late Eocene time (~17-35 Ma).
Results show that the two basins each have distinct mid-Miocene to Pleistocene depocenters. The depth to CRBG in the Portland basin reaches a maximum of ~1,640 ft, 160 ft deeper than the Tualatin basin. Although the Portland basin is separated from the Tualatin basin by the Portland Hills, inversion of gravity data suggests that the two were connected as one continuous basin prior to CRBG deposition. Local thickening of CRBG flows over a gravity low coincident with the Portland Hills suggests that Neogene transpression in the forearc reactivated the SylvanOatfield and Portland Hills faults as high angle reverse faults. This structural inversion separated the once continuous Portland and Tualatin basins in the mid-late Miocene. A change in the stress regime at that time marks the transition from Paleogene forearc extension to deformation dominated by north-south shortening due to collision of the forearc against the Canadian Coast Mountains. An eastward shift of the forearc basin ii depocenter over the Neogene likely reflects uplift of the Coast Range to the west. A change in regional stress in the mid to late-Miocene, along with uplift of the Oregon Coast Range, caused a 10-fold decrease in sediment accumulation rates across the Portland and Tualatin basins. Transpressional oblique-slip faulting continues to deform the region as the forearc undergoes clockwise rotation and collides with the rigid Canadian Coast Mountains to the north.
AU - Scanlon, Darby
DB - Geothermal Data Repository
DP - Open EI | National Renewable Energy Laboratory
DO -
KW - geothermal
KW - energy
KW - tetonic eveolution
KW - isochore maps
KW - modeling
KW - top crbg
KW - eocene basement
KW - paleogene
KW - neogene
KW - resource assement
KW - spatial
KW - temporal
KW - portland
KW - tualatin basin
KW - oregon
KW - geophysics
KW - geophysical
KW - geothermal exploration
LA - English
DA - 2019/07/29
PY - 2019
PB - Portland State University
T1 - Portland DDU Feasibility Study: The Spatial and Temporal Evolution of the Portland and Tualatin Basins, Oregon, USA
UR - https://gdr.openei.org/submissions/1167
ER -
Scanlon, Darby. Portland DDU Feasibility Study: The Spatial and Temporal Evolution of the Portland and Tualatin Basins, Oregon, USA. Portland State University, 29 July, 2019, Geothermal Data Repository. https://gdr.openei.org/submissions/1167.
Scanlon, D. (2019). Portland DDU Feasibility Study: The Spatial and Temporal Evolution of the Portland and Tualatin Basins, Oregon, USA. [Data set]. Geothermal Data Repository. Portland State University. https://gdr.openei.org/submissions/1167
Scanlon, Darby. Portland DDU Feasibility Study: The Spatial and Temporal Evolution of the Portland and Tualatin Basins, Oregon, USA. Portland State University, July, 29, 2019. Distributed by Geothermal Data Repository. https://gdr.openei.org/submissions/1167
@misc{GDR_Dataset_1167,
title = {Portland DDU Feasibility Study: The Spatial and Temporal Evolution of the Portland and Tualatin Basins, Oregon, USA},
author = {Scanlon, Darby},
abstractNote = {The Portland and Tualatin basins are part of the Puget-Willamette Lowland in the Cascadia forearc of Oregon and Washington. The Coast Range to the west has undergone Paleogene transtension and Neogene transpression, which is reflected in basin stratigraphy. To better understand the tectonic evolution of the region, Darby Scanlon modeled three key stratigraphic horizons and their associated depocenters (areas of maximum sediment accumulation) through space and time using well log, seismic, outcrop, aeromagnetic, and gravity data. Three isochore maps were created to constrain the location of Portland and Tualatin basin depocenters during 1) Pleistocene to mid-Miocene (0-15 Ma), 2) eruption of the Columbia River Basalt Group (CRBG, 15.5-16.5 Ma), and 3) MidMiocene to late Eocene time (~17-35 Ma).
Results show that the two basins each have distinct mid-Miocene to Pleistocene depocenters. The depth to CRBG in the Portland basin reaches a maximum of ~1,640 ft, 160 ft deeper than the Tualatin basin. Although the Portland basin is separated from the Tualatin basin by the Portland Hills, inversion of gravity data suggests that the two were connected as one continuous basin prior to CRBG deposition. Local thickening of CRBG flows over a gravity low coincident with the Portland Hills suggests that Neogene transpression in the forearc reactivated the SylvanOatfield and Portland Hills faults as high angle reverse faults. This structural inversion separated the once continuous Portland and Tualatin basins in the mid-late Miocene. A change in the stress regime at that time marks the transition from Paleogene forearc extension to deformation dominated by north-south shortening due to collision of the forearc against the Canadian Coast Mountains. An eastward shift of the forearc basin ii depocenter over the Neogene likely reflects uplift of the Coast Range to the west. A change in regional stress in the mid to late-Miocene, along with uplift of the Oregon Coast Range, caused a 10-fold decrease in sediment accumulation rates across the Portland and Tualatin basins. Transpressional oblique-slip faulting continues to deform the region as the forearc undergoes clockwise rotation and collides with the rigid Canadian Coast Mountains to the north.},
url = {https://gdr.openei.org/submissions/1167},
year = {2019},
howpublished = {Geothermal Data Repository, Portland State University, https://gdr.openei.org/submissions/1167},
note = {Accessed: 2025-04-24}
}
Details
Data from Jul 29, 2019
Last updated Aug 8, 2019
Submitted Jul 30, 2019
Organization
Portland State University
Contact
Darby Scanlon
503.725.3378
Authors
Keywords
geothermal, energy, tetonic eveolution, isochore maps, modeling, top crbg, eocene basement, paleogene, neogene, resource assement, spatial, temporal, portland, tualatin basin, oregon, geophysics, geophysical, geothermal explorationDOE Project Details
Project Name Portland Deep Direct-Use Thermal Energy Storage (DDU-TES) Feasibility Study
Project Lead Arlene Anderson
Project Number EE0008104