Andrew Frassetto
2014-01-14 18:12:25
"The Western U.S. Lithosphere Blues" will be presented at 2 pm EST (7 pm
UTC) on Wednesday, 1/15.
Register to attend: https://www2.gotomeeting.com/register/620067122
You will be emailed a confirmation containing a link for accessing the
webinar. The presentation and subsequent interactions between the
speaker, host, and audience are recorded and made available within a few
days. Access to the webinar archive, along with related materials and
more information on the series is found here:
http://www.iris.edu/hq/webinar/
Presenter: Dr. Rob Porritt, NSF Post-doctoral Fellow, University of
Southern California
Abstract: The Western United States has long been studied as the
typically atypical plate boundary zone. Recent deformation is observed
from the Pacific-North America coast to the Rocky Mountains. Along the
coast and south of the Mendocino Triple Junction in Northern California,
the San Andreas Fault Zone accommodates translational motion between the
Pacific and North American plates through a series of en echelon
strike-slip faults. North of the triple junction, the Juan de Fuca-North
America plate boundary zone is a prolifically aseismic subduction zone
with paleoseismic records of megathrust events, but insufficient events
in the modern age to map the subducting plate deeper than 100km depth.
Moving inboard from the coast, extension through the Basin and Range
Province is pushing apart the Sierra Nevada block and the Colorado
Plateau. Major igneous features include the Tertiary Ignimbrite
Flare-up, the 17Ma Yellowstone and Newberry hotspot tracks, and the
active Cascades Arc.
Using teleseismic and ambient noise data from the Earthscope USArray,
regional seismic networks, and the US backbone seismic network, we image
a generally low seismic wave-speed upper mantle with discrete high
wave-speed features throughout the region. We interpret these features
to be primarily fragments of the Farallon Plate caught in the upper
mantle. Alternatively, many of these features have been interpreted as
lithospheric instabilities as an explanation for the anomalously thin
lithosphere and regional mantle anisotropy inconsistent with simple
plate motion. In this webinar, I present the argument that many, if not
all, of the observed high wave-speed anomalies are pieces of the
Farallon plate. This argument does not rule out the important role
played by lithospheric instabilities in long-term continental growth,
but rather forces the discussion toward the expanded role of oceanic
plate subduction in continental evolution.
Please direct any related inquiries or amusing memes to Andy Frassetto
(andyf<at>iris.edu).
System Requirements
PC-based attendees: Windows® 8, 7, Vista, XP or 2003 Server
Mac®-based attendees: Mac OS® X 10.6 or newer
Mobile attendees: iPhone®, iPad®, Android™ phone or Android tablet
UTC) on Wednesday, 1/15.
Register to attend: https://www2.gotomeeting.com/register/620067122
You will be emailed a confirmation containing a link for accessing the
webinar. The presentation and subsequent interactions between the
speaker, host, and audience are recorded and made available within a few
days. Access to the webinar archive, along with related materials and
more information on the series is found here:
http://www.iris.edu/hq/webinar/
Presenter: Dr. Rob Porritt, NSF Post-doctoral Fellow, University of
Southern California
Abstract: The Western United States has long been studied as the
typically atypical plate boundary zone. Recent deformation is observed
from the Pacific-North America coast to the Rocky Mountains. Along the
coast and south of the Mendocino Triple Junction in Northern California,
the San Andreas Fault Zone accommodates translational motion between the
Pacific and North American plates through a series of en echelon
strike-slip faults. North of the triple junction, the Juan de Fuca-North
America plate boundary zone is a prolifically aseismic subduction zone
with paleoseismic records of megathrust events, but insufficient events
in the modern age to map the subducting plate deeper than 100km depth.
Moving inboard from the coast, extension through the Basin and Range
Province is pushing apart the Sierra Nevada block and the Colorado
Plateau. Major igneous features include the Tertiary Ignimbrite
Flare-up, the 17Ma Yellowstone and Newberry hotspot tracks, and the
active Cascades Arc.
Using teleseismic and ambient noise data from the Earthscope USArray,
regional seismic networks, and the US backbone seismic network, we image
a generally low seismic wave-speed upper mantle with discrete high
wave-speed features throughout the region. We interpret these features
to be primarily fragments of the Farallon Plate caught in the upper
mantle. Alternatively, many of these features have been interpreted as
lithospheric instabilities as an explanation for the anomalously thin
lithosphere and regional mantle anisotropy inconsistent with simple
plate motion. In this webinar, I present the argument that many, if not
all, of the observed high wave-speed anomalies are pieces of the
Farallon plate. This argument does not rule out the important role
played by lithospheric instabilities in long-term continental growth,
but rather forces the discussion toward the expanded role of oceanic
plate subduction in continental evolution.
Please direct any related inquiries or amusing memes to Andy Frassetto
(andyf<at>iris.edu).
System Requirements
PC-based attendees: Windows® 8, 7, Vista, XP or 2003 Server
Mac®-based attendees: Mac OS® X 10.6 or newer
Mobile attendees: iPhone®, iPad®, Android™ phone or Android tablet
