| NSF Org: |
EAR Division Of Earth Sciences |
| Recipient: |
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| Initial Amendment Date: | January 9, 2017 |
| Latest Amendment Date: | January 9, 2017 |
| Award Number: | 1650244 |
| Award Instrument: | Standard Grant |
| Program Manager: |
Steven Whitmeyer
EAR Division Of Earth Sciences GEO Directorate for Geosciences |
| Start Date: | February 1, 2017 |
| End Date: | November 30, 2018 (Estimated) |
| Total Intended Award Amount: | $218,477.00 |
| Total Awarded Amount to Date: | $218,477.00 |
| Funds Obligated to Date: |
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| History of Investigator: |
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| Recipient Sponsored Research Office: |
266 WOODS HOLE RD WOODS HOLE MA US 02543-1535 (508)289-3542 |
| Sponsor Congressional District: |
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| Primary Place of Performance: |
260 Woods Hole Rd Woods Hole MA US 02543-1535 |
| Primary Place of
Performance Congressional District: |
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| Unique Entity Identifier (UEI): |
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| Parent UEI: |
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| NSF Program(s): |
Tectonics, Geomorphology & Land-use Dynam |
| Primary Program Source: |
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| Program Reference Code(s): | |
| Program Element Code(s): |
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| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.050 |
ABSTRACT
Rifting is the process by which continents get stretched and ultimately break apart, potentially leading to the formation of a new ocean basin. Active rifting is currently underway throughout large extents of North America, for example within the Basin and Range Province, along the Rio Grande River in New Mexico, and in the Gulf of California. Rifting areas often focus natural resources (e.g., hydrocarbons, metals, geothermal heat) and can be associated with significant seismic hazards. Understanding the processes that shape rift architecture and landscapes is therefore essential on both a fundamental and societal level. This project specifically investigates the sensitivity of two key rifting processes: fault growth and magmatic activity to topographic stresses, which are forces in Earth's crust due to the build-up of topographic relief. Such stresses are known to affect continental deformation where tectonic plates collide (e.g., Taiwan, the Himalayas), but little is known regarding their influence on continental rifting. These stresses are strongly modulated by the erosive action or rivers and glaciers, and the weight of sediments accumulating in basins and lowlands. This study will combine numerical models and field observations to assess how such active surface processes influence fault development and the spatial extent of volcanic activity during rifting. It will support an early-career scientist as well as a minority graduate student. The products of this study will be widely distributed as part of scientific outreach initiatives, and provide material for educators and wilderness conservation areas.
Numerous field and theoretical studies have addressed the feedbacks between surface processes and strain localization in convergent margins at the scale of entire orogens (100?1000 km). However, very little work has been done in extensional settings, where magmatic processes are an integral part of plate boundary evolution, and sizeable topography grows at the scale of individual normal fault-bounded ranges (10?100 km). The goal of this study is to couple existing rifting models with a realistic parameterization of landscape evolution in order to uncover feedbacks between topography growth and tectono-magmatic deformation at depth. Specifically, the project will first document the full range of mass redistribution efficiency in rifts worldwide using a landscape evolution model that allows direct comparison with observables, e.g., the total relief of normal fault footwalls, the morphology of their major catchment basins, and the sedimentary infill of the hanging wall block. We will then implement these calibrated landscape models as an upper boundary condition in a long-term tectonic model where faults can form spontaneously and magmatic intrusions respond to the ambient stress field. A large suite of numerical simulations will enable tests of the following hypotheses: (1) Denudation of the footwall and deposition on the hanging wall are essential in allowing half-grabens to accommodate offsets commensurate with the thickness of the faulted upper crust; (2) Horst formation is promoted by inefficient surface processes, which preserve relief and favor the build up of topographic stresses near the fault; and (3) Efficient redistribution of surficial masses focuses magmatic activity to the rift axis. Model outputs will be systematically compared with field observations of fault growth and volcanic emplacement to identify the contribution of surface processes to the tectono-magmatic evolution of continental rifts.
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