Publication Date:
2019-10-10
Description:
Understanding the patterns and characteristics of sedimentary deposits on the conjugate
Australian‐Antarctic margins is critical to reveal the Cretaceous‐Cenozoic tectonic, oceanographic, and
climatic conditions in the basin. However, unraveling its evolution has remained difficult due to the
different seismic stratigraphic interpretations on each margin and sparse drill sites. Here, for the first
time, we collate all available seismic reflection profiles on both margins and use newly available offshore
drilling data to develop a consistent seismic stratigraphic framework across the Australian‐Antarctic basins.
We find sedimentation patterns similar in structure and thickness, prior to the onset of Antarctic glaciation,
enabling the basinwide correlation of four major sedimentary units and their depositional history. We
interpret that during the warm and humid Late Cretaceous (~83–65 Ma), large onshore river systems on both
Australia and Antarctica resulted in deltaic sediment deposition offshore. We interpret that the onset of
clockwise bottom currents during the early Paleogene (~58–48 Ma) formed prominent sediment drift
deposits along both continental rises. We suggest that these currents strengthened and progressed farther
east through the Eocene. Coevally, global cooling (〈48 Ma) and progressive aridification led to a large‐scale
decrease in sediment input from both continents. Two major Eocene hiatuses recovered by the Integrated
Ocean Discovery Program site U1356A at the Antarctic continental slope likely formed during this
preglacial phase of low sedimentation and strong bottom currents. Our results can be used to constrain
future paleo‐oceanographic modeling of this region and aid the understanding of the oceanographic changes
accompanying the transition from a greenhouse to icehouse world.
Repository Name:
EPIC Alfred Wegener Institut
Type:
Article
,
isiRev