Crustal structure from the Lützow-Holm Bay to the inland plateau of East Antarctica, based on onshore gravity surveys and broadband seismic deployments

摘要

Onshore gravity measurements were conducted over the inland traverse routes from Syowa Station(69.0S, 39.6E;SYO) to Dome-F(77.4°S, 39.6°E) by the Japanese Antarctic Research Expeditions(1992, 1997, and 1998).The crustal density structure between Lützow-Holm Bay(LHB) and the inland plateau was inferred from Bouguer gravity anomalies along these routes by assuming an initial model of the P-wave structure derived from seismic refraction surveys in the LHB.A decrease in the Bouguer anomalies down to - 200.mGal toward the inland plateau indicate that the crust thickens from 38-40.km at LHB to 48-50.km beneath Dome-F.During the International Polar Year in 2007-2008, the GAmburtsev Mountain SEISmic experiment(GAMSEIS) deployed many broadband stations over the large highland on the ice sheet from the crest of the Gambursev Subglacial Mountains(GSM) to the vicinity of Dome-F.S-wave receiver functions and Rayleigh phase velocities determined using the GAMSEIS data indicate that the cratonic crust surrounding the GSM is 40-47.km thick.These thickness estimates agree with those beneath Dome-F from the JARE's gravity surveys and are also consistent with average Pre-Cambrian terrains.Beneath the GSM, the crustal thickness increases to 55-58.km and has been interpreted as providing isostatic compensation for the high mountain elevations.Accordingly, a long-distance crustal model extending over 3000.km from LHB to Dome-F and to the GSM was compiled, providing significant information for future studies of the tectonic evolution of the Antarctic craton.