Imaging of crustal structure beneath the Larsemann Hills, Antarctica using scattered wave technique – First Results

Abstract

The crustal structure in terms of crustal thickness, shear wave velocities and Poisson's ratio plays a crucial role in understanding and/or deciphering the tectonic setting and its evolution. The receiver function analysis, H–K stacking and inversion techniques are the widely used tools to determine these parameters. In the present study, the data obtained from the first-ever established broadband seismological observatory at Larsemann Hills, East Antarctica has been utilized for the P receiver function (PRF) analysis and H–K stacking to decipher the crustal thickness, Poisson's ratio and the intra-crustal layer. Further, the obtained PRFs were inverted using Bayesian inversion to get the crustal structure. The results obtained from H–K analysis reveal a crustal thickness of ∼37.9 km and the corresponding Poisson's ratio is 0.19. The inversion technique also yielded consistent results, indicating a Moho depth of ∼37 km with a velocity jump from 4.1 km/s to 4.6 km/s and an intra-crustal layer at around 16 km with a velocity jump from 3.95 km/s to 4.06 km/s. It indicates a Poisson's ratio of 0.20. These findings suggest that the crust beneath the Larsemann Hills is felsic in nature and has high crustal shear wave velocity. Further, the variation in the crustal thickness along the coast of the Princess Elizabeth Land (PEL) region, ranging from 37.9 km to 36 km with the intra-crustal layer variation from 16 km to 13 km distinguishes the Neoproterozoic Larsemann Hills from the Archean-Mesoproterozoic Vestfold Hills.