Award Abstract # 0715181
RUI: Paleomagnetic Study of Transitional Fields Recorded Throughout the Cenozoic by Australasian Lavas

NSF Org: EAR
Division Of Earth Sciences
Recipient: UNIVERSITY OF WISCONSIN SYSTEM
Initial Amendment Date: January 23, 2007
Latest Amendment Date: January 23, 2007
Award Number: 0715181
Award Instrument: Standard Grant
Program Manager: Robin Reichlin
EAR
 Division Of Earth Sciences
GEO
 Directorate for Geosciences
Start Date: December 1, 2006
End Date: August 31, 2009 (Estimated)
Total Intended Award Amount: $112,941.00
Total Awarded Amount to Date: $112,941.00
Funds Obligated to Date: FY 2003 = $112,941.00
History of Investigator:
  • Kenneth Hoffman (Principal Investigator)
    khoffman@geology.wisc.edu
Recipient Sponsored Research Office: University of Wisconsin-Madison
21 N PARK ST STE 6301
MADISON
WI  US  53715-1218
(608)262-3822
Sponsor Congressional District: 02
Primary Place of Performance: University of Wisconsin-Madison
21 N PARK ST STE 6301
MADISON
WI  US  53715-1218
Primary Place of Performance
Congressional District:
02
Unique Entity Identifier (UEI): LCLSJAGTNZQ7
Parent UEI:
NSF Program(s): Geophysics,
EAST ASIA AND PACIFIC PROGRAM
Primary Program Source: app-0103 
Program Reference Code(s): 0000, 1031, 5912, 5941, OTHR
Program Element Code(s): 157400, 597800
Award Agency Code: 4900
Fund Agency Code: 4900
Assistance Listing Number(s): 47.050

ABSTRACT

Hoffman
0230347


The most remarkable feature of Earth's magnetic field is its ability to reverse polarity, and much of our knowledge of this phenomenon has come from the paleomagnetic record found in rocks. The goal of this project is to locate, sample and analyze transitional field behavior recorded in Australasia by hotspot-erupted lavas that comprise the Great Dividing Range of Eastern Australia and New Zealand's South Island volcanoes. These volcanics are known to span the past 70 Ma, that is, the entire Cenozoic period, and thus offer an unprecedented opportunity to investigate aspects of Earth's reversing geodynamo from a single regional site over considerable geologic time. In particular, the investigators plan to test the claim that an inordinate number of transitional virtual geomagnetic poles (VGPs) associated with several available paleomagnetic reversal records are found near Australia. This observation has prompted an intriguing possibility, namely, that a concentration of magnetic flux emanating from Earth's fluid outer core below Australasia has largely dominated the field structure during many past reversals, and further, that this flux feature is a consequence of long-standing physical conditions of the lowermost mantle. Because the volcanics of Australia and New Zealand are almost directly above the claimed flux concentration, the project is designed to test this hypothesis. It is anticipated that results from this project will shed light on whether the lower mantle has had such a pronounced effect on the transitioning field over much, or all, of the Cenozoic period, and if so, whether any observable variation, or drift, of the flux feature has occurred since the end of the Mesozoic. In addition, an attempt will be made to determine both paleointensity over this span of time as well as precise radiometric ages of the lava sections. The project will be assisted by undergraduate physics majors working on their senior projects (a mandatory requirement for graduation at Cal Poly State University), exposing them to many aspects of original basic research. Dr Gary Acton of Texas A& M University and Professor Brad Singer of the University of Wisconsin will collaborate on this research.
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PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH

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Hoffman, K.A., and Singer, B.S "Magnetic source separation in earth?s outer core" Science , v.321 , 2008 , p.1800 10.1126/science.1159777
K.A. Hoffman, B.S. Singer, P. Camps, L.N. Hansen, K.A. Johnson, S. Clipperton, C. Carvallo "Stability of Mantle Control Over Dynamo Flux Since the Mid-Cenozoic" Physics of the Earth and Planetary Interiors , v.169 , 2008 , p.20 10.1016/j.pepi.2008.07.012
Kenneth A Hoffman & Andrew J Biggin "A rapid multiple-sample approach to the determination of absolute paleointensity" Journal of Geophysical Research, Solid Earth , v.110 , 2005 , p.B12108 10.1029/2005JB003646
Kenneth A Hoffman & Andrew J Biggin "A rapid multiple-sample approach to the determination of absolute paleointensity" Journal of Geophysical Research, Solid Earth , v.110 , 2005 , p.B12108
Singer, B.S., Hoffman, K.A., Schnepp, E., Guillou, H., "Multiple Brunhes Chron Excursions in the West Eifel (Germany) Volcanics: Support for Long-held Mantle Control on Non-axial Dipole Fields" Physics of the Earth and Planetary Interiors , v.169 , 2008 , p.28 10.1016/j.pepi.2008.05.001
Singer, B.S., K.A. Hoffman, R.S. Coe, L.L. Brown, B.R. Jicha, M.S. Pringle, A. Chauvin "Structural and temporal requirements for geomag-netic field reversal deduced from 40Ar/39Ar dated lava flows" Nature , v.434 , 2005 , p.633
Singer, B.S., K.A. Hoffman, R.S. Coe, L.L. Brown, B.R. Jicha, M.S. Pringle, A. Chauvin "Structural and temporal requirements for geomagnetic field reversal deduced from 40Ar/39Ar dated lava flows" Nature , v.434 , 2005 , p.633 10.1038/nature03431

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