Project details

Middle Miocene eustatic record from the mixed cabonate-siliciclastic record of the northeast Australian Margin (Marion Plateau, ODP Leg 194)

The middle Miocene is a critical interval in Earth history because around 13.5 Ma the East Antarctic ice sheet was permanently established. The formation of the ice sheet is recorded in stable isotopes of oxygen, which show a major increase. Conversely, this must be associated with some fall in global sea-level.

Unfortunately, the sea-level record for the Miocene is the least constrained, and estimates of the amplitude of sea-level for this critical time interval vary.

This project is funded by the American Chemical Society via a Petroleum Research Fund grant. We aim at reconstructing the timing and magnitude if Miocene eustasy using sediment and data from ODP Leg 194, drilled on the Marion Plateau offshore Queensland, Australia. The Marion Plateau is a passive margin covered with mostly Miocene carbonate buildup: it offers a perfect target to reconstruct eustasy via sediment backstripping, and to further constrain these estimates using stable isotopes.

The initial results of this research project are now in press (EPSL). We demonstrate that from 16.5 Ma to 12 Ma, sea-level fell by a composite amplitude of 54-69 meters.  Dr. C├ędric John is the main investigator for this project, but it is the result of a large international collaboration involving Garry D. Karner (ExxonMobil),  Mark Leckie (Umass), Emily Browning (Umass), Chris Lowery (Umass), Zenon Mateo (IODP-USIO) and Brooke Carlson (Chevron).