Geophys. J. Int. (2019) 218, 388–400 doi: 10.1093/gji/ggz154 Advance Access publication 2019 March 27 GJI Gravity, geodesy and tides A crustal thickness model of Antarctica calculated in spherical approximation from satellite gravimetric data Chikondi Chisenga, 1,2 Jianguo Yan 1,3 and Peng Yan 4 1 State Key Laboratory of Information Engineering in Surveying, Mapping and Remote Sensing, Wuhan University, Box 129, Luoyu Road, Wuhan 430079, China. E-mail: jgyan 511@163.com 2 Department of Earth Sciences, Ndata School of Climate and Earth Sciences, Malawi University of Science and Technology, P.O. Box 5196, Limbe, Malawi 3 Instituto de Astronomia y Ciencias Planetarias de Atacama, Universidad de Atacama, Copayapu 485, Chile 4 Chinese Antarctic Center of Surveying and Mapping, Wuhan University, Box 129, Luoyu Road, Wuhan 430079, China Accepted 2019 March 20. Received 2019 March 11; in original form 2018 October 13 SUMMARY The ice cap covering Antarctica has long limited our understanding of the continental-scale crustal model due to its inaccessibility and the resulting logistical difficulties when executing geophysical field work, such as seismograph deployment. Resolving a high spatial resolution crustal model for Antarctica where seismographs are sparsely distributed stimulates scien- tific interest in this relatively less studied continent. In this study, we utilize satellite gravity observations from the global gravity model EIGEN-6C4 to create an alternative crustal thick- ness model of Antarctica. The gravity data were corrected for sediments, topography and ice cover. Furthermore, we considered the gravity effect due to vertical deformation of the lithosphere caused by ice load besides the earth’s curvature in the modelling. We inverted the corrected gravity data using the regularized Bott’s inversion method in spherical approx- imation and constrained the results by seismic observations. This crustal thickness model shows a thicker average crust in East Antarctica and a thinner one in West Antarctica. The thickest crust is in the Gamburtsev Subglacial Mountains with a Moho depth of over 40 km. The thicker crust is particularly evident along the Transantarctic Mountains and the Dronning Maud lands. Comparisons with existing models show a good correlation in gravity-constrained areas. Differences appear in the sedimentary basins and crust with thickness closer to seismic point observations. Overall, our crustal model is relatively improved than the existing gravity derived models. Key words: Gravity anomalies and Earth structure; Antarctica; Gravity inversion; Crustal structure. 1 INTRODUCTION Resolving a high-resolution crustal model of Antarctica stimulates scientific interest. The inaccessibility of this continent limits the effectiveness of standard data collection methods making Antarc- tica a geophysical challenge. The development of the crustal model of Antarctica, however, is essential for understanding the processes responsible for the formation and splitting of Gondwana and the dynamics of plate tectonic motion. The early crustal models in Antarctica were derived from both seismic and gravity observa- tions (Evison et al. 1962). Crustal models from seismic observa- tions nevertheless still suffer from low resolution over Continental Antarctica, which result in greater trade-offs and poorly resolved crustal models due to inaccessibility, cost constraints and unevenly distributed seismic measurements. Advent of satellite gravity has greatly improved crustal thickness mapping in areas not adequately covered by seismic data (e.g. Tedla et al. 2011; Reguzzoni et al. 2013; Tugume et al. 2013; Van der Meijde et al. 2013; van der Meijde et al. 2015a; Llubes et al. 2017; Steffen et al. 2017). For nearly two decades, satellite gravity missions have collected bet- ter observational data over areas with sparsely seismic coverage that were previously not well-studied. Satellite gravity observations combined with terrestrial gravity data are available up to degree and order 2109 in most regions on the Earth (e.g. F¨ orste et al. 2014). The lack of terrestrial data, however, limited the possibil- ity to produce a model with degree and order 2109 in Antarc- tica. Availability of satellite gravity observations has fortunately led to improved crustal thickness estimates at continental scale of Antarctica. Earlier crustal studies in Antarctica started in the 1960s (Evison et al. 1962) with the first continental scale model obtained from a compilation of seismic observations in the 1990s (e.g. Groushin- sky et al. 1992). Over the years, crustal models of Antarctica have been produced from seismic observations (Baranov & Morelli 2013; 388 C  The Author(s) 2019. Published by Oxford University Press on behalf of The Royal Astronomical Society. Downloaded from https://academic.oup.com/gji/article/218/1/388/5420375 by guest on 20 February 2023