The Cenozoic history
of the western US
Goals of the project:
The underplating and subsequent sinking or removal of the Farallon slab
must have been the crucial event that has influenced tectonics in the Western
US since the early Tertiary.
Yet there is no agreement on the fate of the subducting Farallon beneath
North America and various models exist (e.g. Coney and Reynolds, 1977; Bird,
1988; Severinghaus and Atwater, 1990; Humphreys, 1995; Van der Lee and Nolet,
1997).
Models are based on limited datasets, and it is not clear which model,
if any, would satisfy the totality of what is known. In addition, seismological
data sets have greatly increased recently in California/Nevada, and very
soon USArray will provide a quantum leap in station coverage for the rest
of our region of interest, the western part of North America.
It is important to integrate data sets and to develop models that satisfy
all available data - seismological as well as geological.
In more detail, we plan to:
* Modify existing data processing software to allow different types of
data and other constraints to be input into one, general purpose (linear)
inversion strategy. Data include seismic and non-seismic observations.
* Develop or modify flexible (non-uniform) parameterization schemes for
the joint modeling of these data sets. Model parameters include seismic velocities,
anisotropy, attenuation, and density which are interpretable in terms of
constraints on composition, temperature and crystal or crack orientation.
* Test-drive the joint inversion approach on currently available data,
in anticipation of EarthScope, and provide a starting model for future efforts
that will rely heavily on the data produced by the EarthScope observatory,
* Test current hypotheses on Rocky Mountain contraction, western US uplift,
the post-Laramide igmembritic flareup, and the present-day magmatic and
tectonic activity against the starting model,
* Discover at an early stage where the station coverage of USArray leaves
crucial gaps in information needed to understand the tectonic and magmatic
history, to enable us to design effective deployments of the Flexible Array
component.
Collaborators:
Gene Humphreys,
Doug Toomey (U. Oregon)
Suzan van der Lee (Northwestern)
Alan Levander (Rice)
Postdocs:
Raffaella Montelli
Graduate students:
Karin Sigloch
Paul McGee
Funding:
NSF EarthScope
Program
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