by Michael Studinger, Lamont-Doherty Earth Observatory
The Transantarctic Mountains are an extreme example of rift flank uplift, extending over 3500 km across Antarctica and reaching elevations up to 4500 m (see map of the region). The mountain range was formed in the extensional environment associated with the breakup of Gondwanaland. Geological and geophysical work has shown that the Transantarctic Mountains developed along a long-lived lithospheric boundary between East and West Antarctica reactivated by a complex history of extensional and translational microplate motions. The Transantarctic Mountains are not uniform along strike. The variability in fundamental architecture along the mountain range indicates that neither a single event nor a sequence of identical events produced the rift flank uplift.
Most tectonic models assume that the Transantarctic Mountains were uplifted beginning in the Eocene when a phase of rapid denudation has been recorded along the Transantarctic Mountains and when rifting occurred in the basins along the front of the mountains. However, many aspects of the formation of the Transantarctic Mountains and the West Antarctic Rift System remain poorly understood, little studied or controversial.
Recent analysis of aerogeophysical transects across the Transantarctic Mountains (Studinger et al., 2004, 2006) has prompted us to evaluate new ideas for the tectonic and erosional development of the region using dynamic models of lithospheric deformation. This NSF funded project is in close collaboration with Roger Buck and Rob Bialas from Lamont and Paul Fitzgerald from Syracuse University. We have combined numerical models of large-scale (100 to 1000 kilometers) mechanical and thermal evolution of lithosphere with consideration of the small-scale development of individual faults. The small-scale deformation capability means that geologic data, like apatite fission-track studies, can be compared to model predictions. Presently, we considere alternative possibilities for the formation of the Transantarctic Mountains and the Ross Embayment.
Past Aerogeophysical Projects
Two aerogeophysical transects, one in southern Victoria Land and the other one in the Scott and Reedy Glacier region were the basis for this project (see map). The work was a National Science Foundation sponsored project at Lamont-Doherty Earth Observatory. Airborne geophysical surveys within this program were carried out by the Support Office for Aerogeophysical Research (SOAR), a National Science Foundation facility of the Office of Polar Programs located the at the University of Texas. The motivation for studying the Transantarctic Mountains is to try to understand the geodynamics of this extreme rift flank with airborne geophysical surveys and geodynamic modelling. Key results of this project are (for details see Studinger et al., 2004, 2006):
It is important to consider alternative scenarios for the formation of the Transantarctic Mountains.
Published Papers related to the Transantarctic Mountains and the West Antarctic Rift System:
Bialas, R.W., W.R. Buck, M. Studinger, P.G. Fitzgerald, Plateau collapse model for the Transantarctic Mountains West Antarctic Rift System: Insights from numerical experiments, Geology, Vol. 35, No. 8, 687-690, doi: 10.1130/G23825A.1, 2007.
Studinger, M. and Robin E. Bell, Moho Topography of the West Antarctic Rift System from Inversion of Aerogravity Data: Ramifications for Geothermal Heat Flux and Ice Streaming, 10th ISAES Extended Abstract 031: http://pubs.usgs.gov/of/2007/1047/ea/of2007-1047ea031.pdf
Fitzgerald, P., Robert W. Bialas, W. Roger Buck, and Michael Studinger, A Plateau Collapse Model for the Formation of the West Antarctic Rift System/Transantarctic Mountains, 10th ISAES Extended Abstract 087: http://pubs.usgs.gov/of/2007/1047/ea/of2007-1047ea087.pdf
Studinger, M., Bell, R.E., Fitzgerald, P.G., Buck, W.R., Crustal architecture of the Transantarctic Mountains between the Scott and Reedy Glacier region and South Pole from aerogeophysical data, Earth Planet. Sci. Lett., doi:10.1016/j.epsl.2006.07.035, Vol 250 (1-2), p 182-199, 2006.
Bell, R.E., Studinger M., Karner, G.D., Finn, C.A., and Blankenship, D.D., Identifying major sedimentary basins beneath the West Antarctic Ice Sheet from aeromagnetic data analysis, in: D.K. Fütterer, D. Damaske, G. Kleinschmidt, H. Miller, F. Tessensohn, (Eds), Antarctica: Contributions to global earth sciences, Springer-Verlag, Berlin Heidelberg New York, pp. 117 - 122, 2006.
Karner, G.D., Studinger, M., Bell, R.E., Gravity anomalies of sedimentary basins and their mechanical implications: Application to the Ross Sea basins, West Antarctica, Earth Planet. Sci. Lett., 235, p 577 - 596, 2005, doi:10.1016/j.epsl.2005.04.016.
Studinger, M., Bell, R.E., Buck, W.R., Karner,G.D., and Blankenship, D.D., Sub-ice geology inland of the Transantarctic Mountains in light of new aerogeophysical data, Earth Planet. Sci. Lett., 220, 391-408, 2004, doi:10.1016/10.1016/S0012-821X(04)00066-4.
Studinger, M., Bell, R.E., Finn, C.A., and Blankenship, D.D., Mesozoic and Cenozoic extensional tectonics of the West Antarctic rift system from high-resolution airborne geophysical mapping, In: J.A. Gamble, D.N.B. Skinner, and S. Henrys, Antarctica at the close of a millenium, R. Soc. of NZ Bull., 35, pp 563-569, 2002 (download PDF).
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