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.
Highlights
Deployments of broadband seismic arrays on the Antarctic continent have often been the ambitious dreams of dedicated Earth scientists
Existing seismic stations belonging to the Federation Digital Seismographic Network (FDSN) allow resolution of the structure beneath the Antarctic continent at a horizontal scale of 1000 km, which is sufficient to detect fundamental differences in the lithosphere beneath East and West Antarctica, but not to clearly define the structure within each sector
The principle ideas of the Antarctic arrays were derived from components of the “Regional Leapfrogging Arrays (RLA)” and the “Program Oriented Experiments (POE)”
Summary
Deployments of broadband seismic arrays on the Antarctic continent have often been the ambitious dreams of dedicated Earth scientists. The broadband arrays in LHB make a significant contribution to the permanent global network of FDSN, and to such projects as the Global Alliance of Regional Networks (GARNET), RLA, POE, POLENET, and IPY. By combining the passive and active source results, a regional evolution model of LHB is presented to explain the formation of the present mantle structure. Regional tectonic history such as the Pan-African orogenic event, together with the break-up process of Gondwana supercontinent in mid-Mesozoic age, could be the plausible cause of present upper mantle structure. The multidisciplinary seismic investigations reviewed in this paper supply fruitful information for understanding the regional tectonic evolution of this area
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