Compilation of shipborne magnetic and gravity data images crustal structure of Prydz Bay (East Antarctica)

Abstract

A magnetic anomaly map and a free air anomaly map of Prydz Bay, of the adjacent slope and over the continental rise area (63°S-69.5°S, 69°E-81°E) were compiled using Russian, Australian, Japanese and other available data (more than 20 000 km in total length). Adjustment of different data sets was performed before gridding and making contour maps. Crossover differences of the magnetic data were significantly reduced by removing data segments with short-period time variations, by applying time variation corrections of Mawson Station to Australian and Japanese data, and by giving a constant bias to each trackline. Crossover differences of the gravity data were also substantially reduced by applying a constant bias to each cruise/leg. According to the compiled gravity data, in the western part of Prydz Bay the continent ocean boundary is inferred to be situated around the shelf edge at the seaward end of Prydz Channel, while it is in the continental rise in the eastern part. The gravity data also suggest the presence of sediments in the Prydz Bay basin reaching a thickness of about 8 km and overlying a "granitic" layer; the Moho beneath the basin is located at a depth of about 22 km. According to the magnetic data, highly-magnetized rocks occur at shallow depths northwest of the Prydz Bay basin and other parts of Prydz Bay.