Abstract:
Geophysical and geological surveys in and around the Princess Elizabeth Trough, East Antarctica, were carried out in the 1998-99 austral summer season. The survey area covers the Princess Elizabeth Trough, the southern margin of the Kerguelen Plateau, and the Bruce Plateau. Magnetic lineations, which were tentatively identified as anomalies M12 to M10, were recognized on the abyssal plain in the Princess Elizabeth Trough. Six seismic sequences (A to F) are recognized in the Princess Elizabeth Trough and north of the Bruce Plateau. On the southern Kerguelen Plateau, five seismic sequences (KP1 to KP5) are recognized. The geological time of the seismic sequences was estimated based on correlation with lithostratigraphic results of ODP Site 738 and relationship to tectonic history in this area. The geological times of the sequences are as follows. Sequence F on the continental rise is a pre-rift sequence that was deposited in late Jurassic or older time. On the abyssal plain in the Princess Elizabeth Trough, where magnetic lineations are observed, sequence F consists of oceanic crusts and was formed in the Early Cretaceous. Sequence E is a syn-rift sediment formed during late Jurassic to Early Cretaceous time. Sequence D is a post-rift sediments formed in the Early Cretaceous. Sequence C was deposited with marine transgression, which occurred with regional crustal subsidence accompanying the subsidence of the southern Kerguelen Plateau after approximately 90 Ma. Sequences C and B are correlated with sediments formed during Late Cretaceous to middle Eocene time and sediments formed after the middle Eocene, respectively. Sequence A is sediments formed during early Miocene to Quaternary time.