Award Abstract # 1853296
Asthenospheric melting and melt-induced evolution of the lithosphere beneath the Colorado Plateau and the Basin and Range from a seismic characterization of mantle layering

NSF Org: EAR
Division Of Earth Sciences
Recipient: THE TRUSTEES OF COLUMBIA UNIVERSITY IN THE CITY OF NEW YORK
Initial Amendment Date: May 9, 2019
Latest Amendment Date: June 12, 2020
Award Number: 1853296
Award Instrument: Standard Grant
Program Manager: Paul Raterron
praterro@nsf.gov
 (703)292-8565
EAR
 Division Of Earth Sciences
GEO
 Directorate for Geosciences
Start Date: May 15, 2019
End Date: September 30, 2020 (Estimated)
Total Intended Award Amount: $134,910.00
Total Awarded Amount to Date: $134,910.00
Funds Obligated to Date: FY 2019 = $51,843.00
History of Investigator:
  • James Gaherty (Principal Investigator)
    james.gaherty@nau.edu
  • Emily Hopper (Former Principal Investigator)
  • James Gaherty (Former Co-Principal Investigator)
Recipient Sponsored Research Office: Columbia University
615 W 131ST ST
NEW YORK
NY  US  10027-7922
(212)854-6851
Sponsor Congressional District: 13
Primary Place of Performance: Lamont-Doherty Earth Observatory
61 ROUTE 9W
PALISADES
NY  US  10964-1707
Primary Place of Performance
Congressional District:
17
Unique Entity Identifier (UEI): F4N1QNPB95M4
Parent UEI:
NSF Program(s): Geophysics
Primary Program Source: 01001819DB NSF RESEARCH & RELATED ACTIVIT
01001920DB NSF RESEARCH & RELATED ACTIVIT
Program Reference Code(s): 1031
Program Element Code(s): 157400
Award Agency Code: 4900
Fund Agency Code: 4900
Assistance Listing Number(s): 47.050

ABSTRACT

Partial melting in the Earth's upper mantle plays a key role in controlling surface volcanism. It also impacts the evolution of tectonic plates and the deformation of the hot mantle underneath, called the asthenosphere. In recent years, the continental United States has been blanketed by EarthScope's Transportable Array, a program that deployed thousands of seismic instruments. The collected data provide unprecedented new constraints on the structure of the uppermost mantle, informing its dynamics and history of formation and alteration. Here, the researchers analyze the data from the Colorado Plateau, an area with ancient Proterozoic crust. This area has remained relatively undeformed through multiple compression episodes and subsequent extension of the surrounding Basin and Range. The rise of the Plateau from near sea level to its current elevation is not well understood. The volcanism of the Basin and Range is now actively encroaching on the ancient Plateau. By combining seismology and thermodynamic modeling, the team maps out the partial melt and alteration of the uppermost mantle. This project brings new light on the past evolution and present state of an important region of the southwestern United States. It also supports an early-career female scientist, the principal investigator, and provides training to an undergraduate student in the field of seismology.

The team investigates the Colorado Plateau region, where disparate tectonic settings are juxtaposed within a small geographical area. The researchers use surface-wave dispersion data and information derived from S-to-P receiver functions about sharp velocity gradients in the upper mantle. They calculate accurate seismic-velocity models which employ a geologically reasonable layered framework. The models build on the Principal Investigator's previous work with receiver functions, which provides the layered lithosphere-asthenosphere framework in which to invert the dispersion data. The team combine seismic analysis with thermodynamic modeling in a self-consistent way to estimate regional velocity structures. The modeling accounts for the composition, pressure and temperature, as well as melt fraction at depth. These estimates are constrained by compositional and temperature data from the abundant volcanism and xenoliths in the area.

This award reflects NSF's statutory mission and has been deemed worthy of support through evaluation using the Foundation's intellectual merit and broader impacts review criteria.

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