A dynamic process for drowning carbonate reefs on the northeastern Australian margin

Abstract

Drowned carbonate reefs on passive margins are puzzling because of their enormous growth potential compared to typical rates of passive margin subsidence and moderate sea-level fl uctuations. A possible solution to this paradox is that slow processes acting over geologic time weaken reefs and contribute to their ultimate demise. The Australian northeastern marginal plateaus, known for their drowned reefs, underwent a period of accelerated tectonic subsidence during the late Miocene to Pliocene that, combined with a sequence of second-order global sea-level rises, outpaced reef growth and drowned the once-thriving Miocene carbonate platforms. However, the mechanism for the observed anomalous subsidence of this relatively mature passive margin 1000 km from the nearest plate boundary is uncertain. We use a coupled plate, kinematic mantle fl ow model to show that in the late Miocene northeastern Australia overrode subducted slabs from Eocene Melanesian subduction north of Papua New Guinea. We fi nd that the rate of surface subsidence induced by the sinking slabs increases the likelihood that relative sea-level rises outpaced late Miocene reef growth. In addition to the well-known effects of long-term plate processes and short-term global sea-level and climate change, our results demonstrate that deep Earth processes can play a substantial role in driving the evolution of passive margins and coral reefs.

Spatial and temporal patterns of Cenozoic dynamic topography around Australia

“…These observations challenge the notion that the 10 5 −10 8 year growth potential of reefs is ~40 m Myr −1 [ Schlager , ]. They also challenge the assertion that Miocene reef demise along the Marion Plateau, offshore northeast Australia, was caused by rapid drowning triggered by a combination of glacio‐eustatic sea‐level rise and dynamic drawdown at rates of 50–60 m Myr −1 [ DiCaprio et al ., ].…”

Seismic geomorphology and growth architecture of a Miocene barrier reef, Browse Basin, NW-Australia

“…The clear sequence boundary from Marion Plateau is there replaced by a facies shift from tropical to non-tropical, triggered by the general climatic cooling and the submergence by subsidence pulses. DiCaprio et al (2010) recently provided a study with a new approach to explain the strong subsidence on the Australian NE Shelf. They show that mantle processes, namely the overriding of subducted crust slabs, can locally induce accelerated subsidence.…”

The response of a basin‐scale Miocene barrier reef system to long‐term, strong subsidence on a passive continental margin, Barcoo Sub‐basin, Australian North West Shelf

“…DiCaprio et al . () modelled such mantle processes leading to the observed topography, suggesting that subsidence caused by the northward drift of Australia overriding cool slabs of previously subducted Melanesian crust contributed to the late Miocene drowning of the carbonate platforms on the Marion Plateau (ODP Leg 194). On Fig.…”

“…DiCaprio et al . (, ) proposed for the Marion Plateau a subsidence due to mantle processes of ca. 200 m since the middle/late Miocene boundary, and for the Browse Basin a subsidence due to mantle processes close to 100 m for the same time interval.…”

“…However, DiCaprio et al . () recently proposed that mantle‐flow processes can contribute to reef drowning on passive margins. They argued that the development of a topography induced by mantle convection is at the same order of magnitude as eustatic sea‐level variations.…”