Abstract
A gravity survey was conducted along the Mizuho traverse routes in austral summer of 1999-2000 by the 41st Japanese Antarctic Research Expedition (JARE-41). The main purpose of the survey was to obtain detail gravity anomaly along the traverse routes, where deep seismic exploration was simultaneously conducted in order to obtain a fine crustal structure of the Mizuho Plateau. By using SCINTREX (CG-3M) gravity meter, the survey was carried out at 160 sites with about 1 km interval in a distance of 190 km from S16 to Z20 on the traverse routes. Free-air and Bouguer anomalies were calculated using precise locations by GPS measurements, by taking into account an effect of the thick icesheet. The furrowed negative Free-air anomalies are identified around H192, where middle points of the whole traverse routes. Two bedrock elevation models derived both by seismic refraction analyses and radio-echo sounding might correspond to the bottom and the top of a mixture layer composed from ice-moraine rocks over the bedrock surface. Thickness of the crust estimated by Bouguer anomalies is 0.5 - 1 km larger toward inland at the terminal point of Z20 along the profile.
Highlights
The Japanese Antarctic Research Expedition (JARE) has been placed emphasis on the geophysical prospecting on the Mizuho Plateau, East Antarctica
The Mizuho Plateau locates in the Paleozoic Lützow-Holm Complex (LHC), where a regional metamorphism has occurred in 550 Ma as a Pan-African orogenic event [1]
The bedrock topography appears to undulate between +600 m and −600 m throughout the whole traverse routes
Summary
The Japanese Antarctic Research Expedition (JARE) has been placed emphasis on the geophysical prospecting on the Mizuho Plateau, East Antarctica. Several geophysical investigations have been carried out to understand the physical characteristics beneath the continental ice-sheet on the Plateau. Among several SEAL projects, the JARE-41 conducted a seismic refraction and wideangle reflection survey with a dense station distribution along the Mizuho routes in the austral summer of 19992000 [3]. A significant inclination of the Moho discontinuity from inland to the coast was estimated by the crustal density model [9,10] From these previous studies, distribution of the gravity measurement sites was very spare and was not enough numbers in order to compare with the detailed velocity model derived by the JARE-41 seismic exploration. We carried out the gravity survey with a dense distribution of the gravity observation sites along the JARE-41 seismic profile to study crustal density characteristics beneath the Plateau
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