| NSF Org: |
EAR Division Of Earth Sciences |
| Recipient: |
|
| Initial Amendment Date: | June 6, 2007 |
| Latest Amendment Date: | June 6, 2007 |
| Award Number: | 0711293 |
| Award Instrument: | Standard Grant |
| Program Manager: |
David Fountain
EAR Division Of Earth Sciences GEO Directorate for Geosciences |
| Start Date: | July 1, 2007 |
| End Date: | June 30, 2009 (Estimated) |
| Total Intended Award Amount: | $22,752.00 |
| Total Awarded Amount to Date: | $22,752.00 |
| Funds Obligated to Date: |
|
| History of Investigator: |
|
| Recipient Sponsored Research Office: |
1776 E 13TH AVE EUGENE OR US 97403-1905 (541)346-5131 |
| Sponsor Congressional District: |
|
| Primary Place of Performance: |
1776 E 13TH AVE EUGENE OR US 97403-1905 |
| Primary Place of
Performance Congressional District: |
|
| Unique Entity Identifier (UEI): |
|
| Parent UEI: |
|
| NSF Program(s): |
Tectonics, Geomorphology & Land-use Dynam |
| Primary Program Source: |
|
| Program Reference Code(s): |
|
| Program Element Code(s): |
|
| Award Agency Code: | 4900 |
| Fund Agency Code: | 4900 |
| Assistance Listing Number(s): | 47.050 |
ABSTRACT
A research team from the University of North Carolina, University of Oregon, and Western Washington University is conducting a multi-disciplinary examination of a remarkably complete and well exposed archive of late Pliocene to modern paleo-erosion rates preserved in the Fish Creek - Vallecito basin in southern California. Erosion rates in the source are determined from cosmogenic nuclide concentrations in detrital quartz, with corrections for minimal post-depositional nuclide in-growth during rapid burial and exhumation of basinal sediments. Relief production in the source areas are assessed by comparison of (U-Th)/He cooling ages in modern bedrock exposures to detrital minerals in basinal sediments. Depositional ages and sedimentation rates are calibrated with high-precision magnetic reversal and paleointensity stratigraphy. These data yield a high resolution time series of cosmogenic nuclide in-growth of alluvial sediments, which record important changes in catchment-averaged erosion rates through time. Temporal changes in source-area erosion rate are compared to the stratigraphic record of changes in facies architecture and sediment accumulation rates in the basin, allowing assessment of the process-response functions that link erosional forcing to stratigraphic outcomes. Using these approaches, the team is testing hypotheses for tectonic - versus climate driven changes in erosion of the bedrock source: (1) a shift into cooler and more temporally variable climate conditions at the onset of northern hemisphere glaciation approximately 2.5 to 3.0 million years ago caused increased erosion and pronounced progradation of locally derived sediment; and (2) significant, upper mantle-driven uplift lead to relief production and enhanced erosion in the Peninsular Ranges beginning at about 1.0 to 1.3 million years ago.
It is well documented that rates of bedrock erosion and sediment production are closely linked to climate forcing and tectonic construction of topographic relief, though the exact nature and feedback dynamics of those controls remain incompletely understood. Detrital cosmogenic nuclide concentrations in modern stream sediments are widely used for quantifying short-term catchment erosion rates, and for assessing the role of tectonic forcing, lithology, and erosion processes on sediment production rates. While this method is common in studies of modern sediment-catchment systems, its application to ancient sediments is relatively rare, and its use in continuous sedimentary sequences is rarer still. This study is charting new ground through the application of these methods to older sediments. If successful, geologists will have new tools to distinguish the role of climate versus tectonics in landscape evolution.
Please report errors in award information by writing to: awardsearch@nsf.gov.
