Crust and upper mantle structure of the Transantarctic Mountains and surrounding regions from receiver functions, surface waves, and gravity: Implications for uplift models

Abstract

[1] This study uses seismic receiver functions, surface wave phase velocities, and airborne gravity measurements to investigate the structure of the Transantarctic Mountains (TAM) and adjacent regions of the Ross Sea (RS) and East Antarctica (EA). Forty-one broadband seismometers deployed during the Transantarctic Mountain Seismic Experiment provide new insight into the differences between the TAM, RS, and EA crust and mantle. Combined receiver function and phase velocity inversion with niching genetic algorithms produces accurate crustal and upper mantle seismic velocity models. The crustal thickness increases from 20 ± 2 km in the RS to a maximum of 40 ± 2 km beneath the crest of the TAM at 110 ± 10 km inland. Farther inland, the crust of EA is uniformly 35 ± 3 km thick over a lateral distance greater than 1300 km. Upper mantle shear wave velocities vary from 4.5 km s À1 beneath EA to 4.2 km s À1beneath RS, with a transition between the two at 100 ± 50 km inland near the crest of the TAM. The $5 km thick crustal root beneath the TAM has an insufficient buoyant load to explain the entire TAM uplift, suggesting some portion of the uplift may result from flexure associated with a buoyant thermal load in the mantle beneath the edge of the TAM lithosphere.

Glimpses of East Antarctica: Aeromagnetic and satellite magnetic view from the central Transantarctic Mountains of East Antarctica

“…North of the transfer zone, the seismic boundary is not offset and generally follows the center and east side of the Wilkes Subglacial Basin (Figure 9). Local tomography studies suggest that high-velocity, thick lithosphere extends farther east nearly to the coast at ∼75°S [Lawrence et al, 2006a[Lawrence et al, , 2006bWatson et al, 2006]. The difference between the magnetically delineated and seismically delineated edges of the undeformed craton is puzzling and unusual.…”

“…Crustal thicknesses of 35-37 km beneath the polar plateau and ∼40 km beneath the TAM correspond to those modeled from gravity, surface, and bed elevation data in southern Victoria Land [Studinger et al, 2004] and the South Pole area [Studinger et al, 2006] and from seismic and gravity data in Victoria Land [Lawrence et al, 2006a]. The transition from the modified craton block to the outboard Neoproterozoic-Mesozoic block is marked by a steep gravity gradient (Figure 8) that, together with the magnetic data, suggests that the inferred Marsh fault (Figure 2) dips steeply eastward, coincident with an increase in crustal thickness from ∼35 to 42 km under the axis of the central TAM.…”

“…[6] Seismic velocity data indicate that crustal thickness varies from about 20 km in the Ross Sea basin to about 40 km at the range crest and about 35 km in inland East Antarctica [Lawrence et al, 2006a]. Gravity models indicate that thinner crust (∼30 km) underlies the northern Wilkes Subglacial Basin [Ferraccioli et al, 2001], a long-wavelength down warp behind the Transantarctic Mountains that extends from the Oates Coast to southern Victoria Land ( Figure 1a); it is thought to contain thin crust overlain by several kilometers of sediment fill, but its origin is enigmatic [Studinger et al, 2004;Ferraccioli et al, 2001Ferraccioli et al, , 2009.…”

Antarctic ice sheet thickness estimation using the horizontal-to-vertical spectral ratio method with single-station seismic ambient noise

“…Over the past two decades, several temporary seismic arrays have been deployed in Antarctica, including the TransAntarctic Mountains Seismic Experiment (TAMSEIS, 2000(TAMSEIS, -2003 (Lawrence et al, 2006), the Gamburtsev Antarctic Mountains Seismic Experiment (GAMSEIS, 2007(GAMSEIS, -2012 (Hansen et al, 2010) and the Polar Earth Observing Network/Antarctic Network (POLENET/ANET, 2007-2016) (Chaput et al, 2014). Despite their relatively sparse distribution compared to many dense seismic arrays on other continents, these three arrays combined effectively cover East and West Antarctica as well as the Transantarctic Mountains region (Fig.…”

“…Seismic waves also become more complex when traveling through an ice sheet with thicknesses ranging from hundreds to thousands of meters. Thus, accurate ice sheet thickness is a critical metric for recognizing and denoising seismic multiples trapped inside the ice sheet when imaging crustal and mantle structures below the ice sheet (Lawrence et al, 2006;Hansen et al, 2009Hansen et al, , 2010. Therefore, a better understanding of ice sheet thickness and structures can also improve the study of the geological structure underneath the ice sheet in Antarctica.…”