The Structure of the Continental Margin off Wilkes Land and Terre Adélie Coast, East Antarctica

IODP Expedition 318: From Greenhouse to Icehouse at the Wilkes Land Antarctic Margin

“…Initial studies now also reveal details of the tectonic history of the Australo-Antarctic Gulf (at 53 Ma), the onset of the second phase of rifting between Australia and Antarctica (Colwell et al, 2006;Close et al, 2009), ever-subsiding margins and deepening, to the present ocean/continent configuration. Tectonic and climatic change turned the initially shallow, broad subtropical Antarctic Wilkes Land offshore shelf into a deeply subsided basin with a narrow ice-infested margin (Fig.…”

“…We therefore planned to core several sequences from the Pleistocene and Pliocene that formed during interglacial intervals of exceptional warmth, periods that may provide valuable information about Antarctica's response to warming predicted in the centuries ahead. Furthermore, seismic reflection and shallow coring data indicate that the activity related to the commencement of rapid seafloor spreading in the Australia-Antarctic Basin (A AB), reported to initiate around the same time (~50 Ma; Colwell et al, 2006). Also, combined Site U1356 and ODP Leg 189 dinocyst distribution patterns suggest earliest through-flow of South Pacific Antarctic waters through the Tasmanian Gateway to be coeval with this tectonic phase.…”

Antarctica‘s continent-ocean transitions: consequences for tectonic reconstructions

“…A vast amount of seismic reflection, gravity, and magnetic data as well as nonreversed sonobuoy refraction data collected by Australian and Russian scientists in the last few years allows a characterization of the Wilkes Land and Terre Adélie Coast margin east of Bruce Rise ( Figure 5) (Stagg et al, 2005;Colwell et al, 2006;Leitchenkov et al, 2007b). Along most of this margin the shelf slope is underlain by a marginal rift zone of stretched and faulted basement.…”

Comment on "Major Australian-Antarctic Plate Reorganization at Hawaiian-Emperor Bend Time"

“…Integrated interpretation of geophysical data from both the Australian and Antarctic margins indicates that the onset of breakup was complex and diachronous with the oldest seafloor spreading anomalies identified as chron 32y (3,4) and chron 33o (3) in the central sector of the AustralianAntarctic Basin, between 127 and 133°E on the Australian margin and~125 and 128°E on the Antarctic margin. The Whittaker et al (1) identification of seafloor spreading magnetic anomalies for chrons 33o, 34y, and the QZB in this sector is at odds with these interpretations, and any finite reconstruction poles older than chron 32y are speculative.…”

“…Colwell et al (4) interpreted that magnetic anomalies landward of the identifications for chron 20o (to the west) to chron 24o (to the east) along the Sabrina Coast Sector of the Antarctic margin (110 to 124°E) possibly lie on transitional continental-oceanic crust with major magmatic components. This interpretation was based on the same profiles as the magnetic anomalies interpreted by (1), data collected by the Australian Government in 2001 and 2002.…”