Skip to main content
OSTI.GOVU.S. Department of Energy Office of Scientific and Technical Information
U.S. Department of Energy
Office of Scientific and Technical Information
 

The spatial and temporal evolution of the Portland and Tualatin forearc basins, Oregon, USA

Journal Article · · Geosphere
DOI:https://doi.org/10.1130/ges02298.1· OSTI ID:1828069
 [1];  [2];  [2];  [2]
  1. Portland State Univ., OR (United States); Portland State University
  2. Portland State Univ., OR (United States)
+ Show Author Affiliations
The Portland and Tualatin basins are part of the Salish-Puget-Willamette Lowland, a 900-km-long, forearc depression lying between the volcanic arc and the Coast Ranges of the Cascadia convergent margin. Such inland seaways are characteristic of warm, young slab subduction. We analyzed the basins to better understand their evolution and relation to Coast Range history and to provide an improved tectonic framework for the Portland metropolitan area. We model three key horizons in the basins: (1) the top of the Columbia River Basalt Group (CRBG), (2) the bottom of the CRBG, and (3) the top of Eocene basement. Isochore maps constrain basin depocenters during (1) Pleistocene to mid-Miocene time (0–15 Ma), (2) CRBG (15.5–16.5 Ma), and (3) early Miocene to late Eocene (ca. 17–35 Ma) time. Results show that the Portland and Tualatin basins have distinct mid-Miocene to Quaternary depocenters but were one continuous basin from the Eocene until mid-Miocene time. A NW-striking gravity low coincident with the NW-striking, fault-bounded Portland Hills anticline is interpreted as an older graben coincident with observed thickening of CRBG flows and underlying sedimentary rocks. Neogene transpression in the forearc structurally inverted the Sylvan-Oatfield and Portland Hills normal faults as high-angle dextral-reverse faults, separating the Portland and Tualatin basins. An eastward shift of the forearc basin depocenter and ten-fold decrease in accommodation space provide temporal constraints on the emergence of the Coast Range to the west. Clockwise rotation and northward transport of the forearc is deforming the basins and producing local earthquakes beneath the metropolitan area.
Research Organization:
Portland State Univ., OR (United States)
Sponsoring Organization:
USDOE Office of Energy Efficiency and Renewable Energy (EERE), Renewable Power Office. Geothermal Technologies Office
Grant/Contract Number:
EE0008104
OSTI ID:
1828069
Journal Information:
Geosphere, Journal Name: Geosphere Journal Issue: 3 Vol. 17; ISSN 1553-040X
Publisher:
Geological Society of AmericaCopyright Statement
Country of Publication:
United States
Language:
English

References (41)

A note on fault reactivation journal January 1985
The Portland Hills Fault: uncovering a hidden fault in Portland, Oregon using high-resolution geophysical methods journal June 2003
Global plate boundary evolution and kinematics since the late Paleozoic journal November 2016
Active tectonics of northwestern U.S. inferred from GPS-derived surface velocities: PACIFIC NORTHWEST GPS journal February 2013
Coseismic Rupture Geometry and Slip Rupture Process During the 2018 Mw 7.1 Anchorage, South‐Central Alaska Earthquake: Intraplate Normal Faulting by Slab Tear Constrained by Geodetic and Teleseismic Data journal January 2020
Source‐Dependent Amplification of Earthquake Ground Motions in Deep Sedimentary Basins journal June 2019
Seismic velocity structure of the Puget Sound Region from 3-D Non-linear tomography journal November 1997
Cenozoic plate motions and the volcano-tectonic evolution of western Oregon and Washington journal April 1984
Sedimentary underplating at the Cascadia mantle-wedge corner revealed by seismic imaging journal July 2011
Megathrust shear force controls mountain height at convergent plate margins journal June 2020
Petrofacies and Petrologic Evolution of the Late Cretaceous Fore-Arc Basin, Northern and Central California journal May 1978
Contemporary deformation in the Yakima fold and thrust belt estimated with GPS journal July 2016
Fault locking, block rotation and crustal deformation in the Pacific Northwest journal June 2007
Crustal Architecture of the Cascadia Forearc journal October 1994
Miocene Tholeiitic Basalts of Coastal Oregon and Washington and Their Relations to Coeval Basalts of the Columbia Plateau journal January 1973
Intracanyon flows of the Columbia River Basalt Group in the lower Columbia River Gorge and their relationship to the Troutdale Formation journal January 1984
Case for periodic, colossal jökulhlaups from Pleistocene glacial Lake Missoula journal January 1985
Tectonic setting of the Portland-Vancouver area, Oregon and Washington: Constraints from low-altitude aeromagnetic data journal September 1995
Late Cenozoic exhumation of the Cascadia accretionary wedge in the Olympic Mountains, northwest Washington State journal August 1998
New aeromagnetic data reveal large strike-slip (?) faults in the northern Willamette Valley, Oregon journal August 2000
Location, structure, and seismicity of the Seattle fault zone, Washington: Evidence from aeromagnetic anomalies, geologic mapping, and seismic-reflection data journal February 2002
Modern and ancient sedimentary basins: Comparative accumulation rates journal January 1976
Two-phase stratigraphic model of foreland-basin sequences journal January 1988
High-angle reverse faults, fluid-pressure cycling, and mesothermal gold-quartz deposits journal January 1988
Stratigraphic modeling of foreland basins: Interpreting thrust deformation and lithosphere rheology journal January 1990
Fore-arc migration in Cascadia and its neotectonic significance journal January 1998
Late Miocene exhumation and uplift of the Washington Cascade Range journal January 2002
Seismically imaged relict slab from the 55 Ma Siletzia accretion to the northwest United States journal January 2011
Steady rotation of the Cascade arc journal September 2013
Tectonic evolution of the Tualatin basin, northwest Oregon, as revealed by inversion of gravity data journal April 2014
Diverse rupture modes for surface-deforming upper plate earthquakes in the southern Puget Lowland of Washington State journal August 2014
Northward migration of the Oregon forearc on the Gales Creek fault journal February 2020
Seismic Source Characterization of Faults in the Portland and Tualatin Basins and a Paleoseismic Study of the Gales Creek Fault, or conference January 2019
Provenance of the Hillsboro Formation: Implications for the Structural Evolution and Fluvial Events in the Tualatin Basin, Northwest Oregon journal January 2000
Gravity Study through the Tualatin Mountains, Oregon: Understanding Crustal Structure and Earthquake Hazards in the Portland Urban Area journal August 2004
Identifying the Rupture Plane of the 2001 Nisqually, Washington, Earthquake journal June 2008
Broadband Synthetic Seismograms for Magnitude 9 Earthquakes on the Cascadia Megathrust Based on 3D Simulations and Stochastic Synthetics, Part 1: Methodology and Overall Results journal August 2018
Multiple Holocene Earthquakes on the Gales Creek Fault, Northwest Oregon Fore-Arc journal October 2020
The 30 November 2018 Mw 7.1 Anchorage Earthquake journal October 2019
Tholeiitic and alkalic basalts of the Eocene Siletz River Volcanics, Oregon Coast Range journal June 1968
Slip History of the 1995 Kobe, Japan, Earthquake Determined from Strong Motion, Teleseismic, and Geodetic Data. journal January 1996

Similar Records

Multiple Holocene Earthquakes on the Gales Creek Fault, Northwest Oregon Fore-Arc
Journal Article · Tue Oct 20 00:00:00 EDT 2020 · Bulletin of the Seismological Society of America · OSTI ID:1828067
Tectonic implications of a high-resolution aeromagnetic survey of the Portland basin, Oregon and Washington
Conference · Wed Mar 31 23:00:00 EST 1993 · Geological Society of America, Abstracts with Programs; (United States) · OSTI ID:5422799
Elevation Grid for top Columbia River Basalt (CRBG) in the Portland Basin used in DDU Feasibility Study
Dataset · Fri Nov 30 23:00:00 EST 2018 · OSTI ID:1493810

Related Subjects

15 GEOTHERMAL ENERGY