Broadband Seismic Deployments for Imaging the Upper Mantle Structure in the Lützow-Holm Bay Region, East Antarctica

Abstract

Broadband seismic deployments have been carried out in the Lützow-Holm Bay region (LHB), Dronning Maud Land, East Antarctica. The recorded teleseismic and local events are of sufficient quality to image the structure and dynamics of the crust and mantle of the terrain. Passive seismic studies by receiver functions and shear wave splitting suggest a heterogeneous upper mantle. Depth variations in topography for upper mantle discontinuities were derived from long period receiver function, indicating a shallow depth discontinuity at 660 km beneath the continental area of LHB. These results provide evidence of paleo upwelling of the mantle plume associated with Gondwana break-up. SKS splitting analysis anticipated a relationship between “fossil” anisotropy in lithospheric mantle and past tectonics. Moreover, active source surveys (DSSs) imaged lithospheric mantle reflections involving regional tectonic stress during Pan-African and succeeding extension regime at the break-up. By combining the active and passive source studies of the mantle structure, we propose an evolution model of LHB for constructing the present mantle structure.

Passive Seismic Deployments from the Lützow-Holm Bay to Inland Plateau of East Antarctica: The Japanese IPY Contribution to Structure and Seismicity

“…Variations in crustal thickness along the coast may reflect the tectonic history involving super-continent evolution, with increasing metamorphic grade in crystalline crust towards the southern part of LHB. Along with the crustal studies, long period receiver functions (after 0.2 Hz low-pass filter) demonstrate the depth variations in mantle discontinuities for both 410 km and 660 km in LHB, respectively [9]. The azimuthal heterogeneities were also identified in both 410 km and 660 km discontinuities in the two azimuth ranges of 20˚ -50˚ and 200˚ -260˚.…”

“…Moreover, the seismic deployments between Eastern Dronning Maud Land and Enderby Land area, by the Japanese Antarctic Research Expedition (JARE; [9]) significantly contributed as a part of both POLENET and AGAP/GAMSEIS. From the data obtained, local and regional seismic signals associated with ice movements, oceanic loading and local meteorological variations were recorded in addition to a significant number of teleseismic events.…”

An Overview of Seismological Projects during the International Polar Year

“…the data from these stations also contributed to the Global Alliance of Regional Networks (GARNET; Figure 2), and the lithospheric structure, upper mantle discontinuity, and seismic isotropy-related tectonics around the region have been identified [11,12]. Moreover, the other nations besides Japan, such as the UK, Australia, Italy, France, China, and New Zealand, developed their own new seismic networks near the coastal area of the Antarctic continent, providing precious regional dataset to POLENET.…”

Seismological Studies on the Deep Interiors of the Earth Viewed from the Polar Region

“…As one of the tectonic regions in East Antarctica, the Lützow-Holm Bay area where the Japanese permanent station (Syowa) has been situated, the upper mantle isotropy and seismic discontinuity were studied during the IPY by using broadband seismic data distributed by the Japanese Antarctic Research Expedition (JARE) [20,21]. A long-period P-wave receiver…”