USAP-DC

Intellectual Merit:
To understand Antarctica's geodynamic development, origin of the Transantarctic Mountains (TAMs) and the Wilkes Subglacial Basin (WSB) must be determined. Current constraints on the crustal thickness and seismic velocity structure beneath the TAMs and the WSB are limited, leading to uncertainties over competing geologic models that have been suggested to explain their formation. The PI proposes to broaden the investigation of this region with a new seismic deployment, the Transantarctic Mountains Northern Network (TAMNNET), a 15-station array across the northern TAMs and the WSB that will fill a major gap in seismic coverage. Data from TAMNNET will be combined with that from other previous and ongoing seismic initiatives and will be analyzed using proven modeling techniques to generate a detailed image of the seismic structure beneath the TAMs and the WSB. These data will be used to test three fundamental hypotheses: the TAMs are underlain by thickened crust, the WSB is characterized by thin crust and thick sedimentary layers, and slow seismic velocities are prevalent along strike beneath the TAMs. Results from the proposed study will provide new information about the nature and formation of the Antarctic continent and will help to advance our understanding of important global processes, such as mountain building and basin formation. The proposed research also has important implications for other fields of Antarctic science. Constraints on the origin of the TAMs uplift are critical for climate and ice sheet models, and new information acquired about variations in the thermal and lithospheric structure beneath the TAMs and the WSB will be used to estimate critical ice sheet boundary conditions.

Broader impacts:
This project incorporates three educational strategies to promote the integration of teaching and research. Graduate students will be trained in Antarctic tectonics and seismic processing through hands-on fieldwork and data analysis techniques. Through NSF's PolarTREC program, the PI will work with K-12 educators. The PI will develop a three-week summer field program for recent high school graduates and early-career undergraduate students from Minority-Serving Institutions in Alabama. Teaching materials and participant experiences will be shared with individuals outside the program via a course website. Following the summer program, participants who were particularly engaged will be offered internship opportunities to analyze TAMNNET data. In successive years, the students could assist with fieldwork and could be recruited into the graduate program under the PI's supervision. Ultimately, this program would not only serve to educate undergraduates but would also generate a pipeline of underrepresented students into the geosciences.

Person	Role
Hansen, Samantha	Investigator

Antarctic Earth Sciences

Award # 1148982

USAP-1148982_1

None in the Database

Repository	Title (link)	Format(s)	Status
USAP-DC	Upper Mantle Seismic Structure beneath the Northern Transantarctic Mountains from Regional P- and S-wave Tomography	None	exist
USAP-DC	Upper Mantle Shear Wave Velocity Structure beneath the Northern Transantarctic Mountains	None	exist
USAP-DC	Shear Wave Splitting Analysis and Seismic Anisotropy beneath the Northern Transantarctic Mountains	None	exist
USAP-DC	Crustal Structure beneath the Northern Transantarctic Mountains and Wilkes Subglacial Basin: Implications for Tectonic Origins	None	exists

1. Graw, J.H., A.N. Adams, S.E. Hansen, D.A. Wiens, L. Hackworth, and Y. Park, (2016). Upper mantle shear wave velocity structure beneath northern Victoria Land, Antarctica: Volcanism and uplift in the northern Transantarctic Mountains, Earth Planet. Sci. Lett., 449, 48-60, doi:10.1016/j.epsl.2016.05.026. (doi:10.1016/j.epsl.2016.05.026)
2. White-Gaynor, A., Nyblade, A., Aster, R.C., Wiens, D., Bromirski, P., Gerstoft, P., Stephen, R., Hansen, S., Wilson, T., Dalziel, I. Huerta, A., Winberry, P., Anandakrishnan, S., Heterogeneous upper mantle structure beneath the Ross Sea Embayment and Marie Byrd Land, West Antarctica, revealed by P-wave tomography, EPSL, 513, 40 - 50, 10.1016/j.epsl.2019.02.013, 2019. (doi:10.1016/j.epsl.2019.02.013)
3. Lucas, E. M., Soto, D., Nyblade, A. A., Lloyd, A. J., Aster, R. C., Wiens, D. A., … Huerta, A. D. (2020). P- and S-wave velocity structure of central West Antarctica: Implications for the tectonic evolution of the West Antarctic Rift System. Earth and Planetary Science Letters, 546, 116437. (doi:10.1016/j.epsl.2020.116437)
4. Hansen, S. E., Kenyon, L. M., Graw, J. H., Park, Y., & Nyblade, A. A. (2016). Crustal structure beneath the Northern Transantarctic Mountains and Wilkes Subglacial Basin: Implications for tectonic origins. Journal of Geophysical Research: Solid Earth, 121(2), 812–825. (doi:10.1002/2015jb012325)
5. Graw, J. H., & Hansen, S. E. (2017). Upper mantle seismic anisotropy beneath the Northern Transantarctic Mountains, Antarctica from PKS, SKS, andSKKS splitting analysis. Geochemistry, Geophysics, Geosystems, 18(2), 544–557. (doi:10.1002/2016gc006729)
6. Lucas, E. M., Nyblade, A. A., Accardo, N. J., Lloyd, A. J., Wiens, D. A., Aster, R. C., Wilson, T. J., Dalziel, I. W., Stuart, G. W., O’Donnell, J. P., Winberry, J. P., & Huerta, A. D. (2022). Shear Wave Splitting Across Antarctica: Implications for Upper Mantle Seismic Anisotropy. Journal of Geophysical Research: Solid Earth, 127(4). Portico. (doi:10.1029/2021jb023325)
7. Lucas, E. M., Nyblade, A. A., Aster, R. C., Wiens, D. A., Wilson, T. J., Winberry, J. P., & Huerta, A. D. (2023). Tidally Modulated Glacial Seismicity at the Foundation Ice Stream, West Antarctica. Journal of Geophysical Research: Earth Surface, 128(7). Portico. (doi:10.1029/2023jf007172)