NSF Org:	EAR Division Of Earth Sciences
Awardee:	UTAH STATE UNIVERSITY
Initial Amendment Date:	June 28, 2020
Latest Amendment Date:	June 28, 2020
Award Number:	2016338
Award Instrument:	Standard Grant
Program Manager:	Audrey Huerta ahuerta@nsf.gov  (703)292-7438 EAR  Division Of Earth Sciences GEO  Directorate For Geosciences
Start Date:	July 1, 2020
End Date:	June 30, 2022 (Estimated)
Total Intended Award Amount:	$42,331.00
Total Awarded Amount to Date:	$42,331.00
Funds Obligated to Date:	FY 2020 = $42,331.00
History of Investigator:	Dennis  Newell (Principal Investigator) dennis.newell@usu.edu
Awardee Sponsored Research Office:	Utah State University 1000 OLD MAIN HILL LOGAN UT  US  84322-1000 (435)797-1226
Sponsor Congressional District:	01
Primary Place of Performance:	Utah State University Logan UT  US  84322-4505
Primary Place of Performance Congressional District:	01
Unique Entity Identifier (UEI):	SPE2YDWHDYU4
Parent UEI:	SPE2YDWHDYU4
NSF Program(s):	Tectonics
Primary Program Source:	040100 NSF RESEARCH & RELATED ACTIVIT
Program Reference Code(s):	7916
Program Element Code(s):	1572
Award Agency Code:	4900
Fund Agency Code:	4900
Assistance Listing Number(s):	47.050

ABSTRACT

The Denali Fault in Alaska is a >2000-km-long, active, predominately horizontal motion (strike-slip) fault zone associated with the boundary between the North American and the Pacific tectonic plates. Fault zones are breaks in the Earth’s crust that can act as conduits for transport of water from great depths (>20 miles). Major questions exist about how deeply this fault penetrates into the crust, how the multiple strands of the fault are connected at depth, and how the changes in the style of faulting along its trace impact the circulation of deep groundwater. To inform these unknowns, this study will examine the isotope geochemistry of springs that discharge along the Denali fault zone. Results will improve the understanding of the Denali Fault, particularly with respect to the depth and interconnectedness of fault strands, with important implications for earthquake hazards and the distribution of geothermal and mineral resources. This study fosters a new interdisciplinary collaboration between investigators in Alaska and Utah, and advances education and training for undergraduate students, including those from underrepresented groups.

This one-year project will examine the helium isotope signature of springs discharging along the Denali Fault system and along splay thrust faults. The fault system transitions east-to-west from a transform fault to a continental strike-slip fault, and provides a system to test hypotheses on the nature of continental strike-slip faults and splay thrust faults as potential conduits for mantle-derived fluids. Helium isotope (3He/4He), carbon, oxygen, and hydrogen stable isotope, and water chemistry data from springs will constrain the contribution of mantle-derived fluids to test competing geophysics models on variations in the crustal scale of the Denali Fault system, the depth splay faults connect with the master strand of the Denali Fault, and possible influences of the underlying subducting slab geometry on fluid isotopic composition. For this exploratory study, ten springs were selected along the trace of the Denali Fault system in Alaska, including six CO2-rich springs that deposit travertine to maximize capturing signals from deep flow paths. In addition to advancing understanding of the structural and geochemical record of fluid-fault interaction, this study provides a framework for future helium isotopic analysis of additional springs along the Denali Fault system, other regional structures, and the tectonic-magmatic regime responsible for geothermal resources across Alaska.

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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