Award Abstract # 0911742
Geologic and Paleomagnetic Study of the Basal Belt Supergroup, Little Belt Mountains, Montana: Testing the Siberian Connection to Rodinia

NSF Org: EAR
Division Of Earth Sciences
Recipient: UNIVERSITY OF MONTANA
Initial Amendment Date: July 26, 2009
Latest Amendment Date: July 26, 2009
Award Number: 0911742
Award Instrument: Standard Grant
Program Manager: Stephen Harlan
EAR
 Division Of Earth Sciences
GEO
 Directorate for Geosciences
Start Date: August 1, 2009
End Date: July 31, 2011 (Estimated)
Total Intended Award Amount: $55,466.00
Total Awarded Amount to Date: $55,466.00
Funds Obligated to Date: FY 2009 = $55,466.00
ARRA Amount: $55,466.00
History of Investigator:
  • James Sears (Principal Investigator)
    james.sears@umontana.edu
Recipient Sponsored Research Office: University of Montana
32 CAMPUS DR
MISSOULA
MT  US  59812-0003
(406)243-6670
Sponsor Congressional District: 01
Primary Place of Performance: University of Montana
32 CAMPUS DR
MISSOULA
MT  US  59812-0003
Primary Place of Performance
Congressional District:
01
Unique Entity Identifier (UEI): DAY7Z8ZD48Q3
Parent UEI:
NSF Program(s): Tectonics
Primary Program Source: 01R00910DB RRA RECOVERY ACT
Program Reference Code(s): 0000, 6890, 9150, OTHR
Program Element Code(s): 157200
Award Agency Code: 4900
Fund Agency Code: 4900
Assistance Listing Number(s): 47.050

ABSTRACT

This award is funded under the American Recovery and Reinvestment Act of 2009 (Public Law 111-5).

The passing of enormous amounts of time obscures Earths tectonic history much as it does human history. The ancient tectonic connections of continents are of great interest to society because they control critical aspects of, for example, the distribution of energy and mineral resources. Geologists have proposed that the tectonic breakup of the hypothetical supercontinent, Rodinia, separated Siberia and North America and triggered significant geologic events, including global ice-ages, sea-level changes, and the origin and dispersal of animal life. This project will test the magnetic memory of ancient sedimentary rock formations in central Montana for comparison with previous results from similar sediments in Siberia to evaluate whether these now distant landmasses were adjacent parts of a single supercontinent about 1.5 billion years ago. If so, they should converge on a common magnetic pole position when they are restored through time using the magnetic memory of the rocks. In addition to revealing the ancient connections of the continents, results from this study will improve our basic understanding of the nature and history of the ancient magnetic field.

Geoscientists have proposed several configurations for the hypothetical Precambrian supercontinent Rodinia. The investigators will evaluate these models by deriving North American paleopole positions for the interval 1.6-1.5 billion years ago from undisturbed sedimentary rocks of the basal Belt Supergroup in the Little Belt Mountains of central Montana. The results will be compared with previous paleomagnetic positions that the PIs derived from similar and correlative strata on the Siberian craton, to test the relative locations of North America and Siberia within Rodinia. Geologists generally consider that Siberia and North America were already adjacent parts of a single large continent well before Rodinia formed, and became separated only when Rodinia broke apart. Successful paleomagnetic modeling in this project will fill in a critical time gap for the North American apparent polar wander path. The PI will collect oriented samples as part of ongoing collaborations and the group will use demagnetization methods to analyze the samples at leading international laboratories. The goal is to compare the results with those already obtained from Siberian samples. Using the same lab, techniques, and personnel to analyze the Montana samples will yield data directly comparable with the Siberian results, and ensure the veracity of the model wander paths.

PUBLICATIONS PRODUCED AS A RESULT OF THIS RESEARCH

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A.K. Khudoley, K.R. Chamberlain, A.K. Schmitt, T.M. Harrison, A.V. Prokopiev, J.W. Sears, R.V. Veselovskiy, V.F. Proskurnin "New U-Pb baddeleyite ages from mafic intrusions from Taimyr, northern and southeastern Siberia: implications for tectonics and stratigraphy" Russian Academy of Sciences , 2009
MacLean, J.S., Sears, J.W., and Chamberlain, K.R "SHRIMP and LAICPMS detrital zircon geochronology of Mesoproterozoic to early Cambrian samples from SE Siberia and SW Laurentia: Implications for Rodinia reconstruction" Geological Society of America Abstracts with Programs , v.42 , 2010 , p.517
Sears, J.W. "Breaking up is hard to do: Evolution of the North American Cordilleran margin in the context of the Siberian connection" Geological Society of America Abstracts with Programs , v.41 , 2009 , p.181
Sears, J.W., Link, P.K., Balgord, E.A., and Mahoney, J.B. "Quartzite of Argenta, Beaverhead County, Montana, revisited: Definitive evidence of Precambrian age indicates edge of Belt basin" Northwest Geology , v.39 , 2010 , p.41

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