Relative Control of Paleoceanography, Climate, and Eustasy over Heterozoan Carbonates: A Perspective from Slope Sediments of the Marion Plateau (ODP LEG 194)

Abstract

In this paper we explore the relative control of paleoceanography, eustasy, and water temperature over the evolution of a carbonate slope system deposited on the Marion Plateau (Northeastern Australia). Growth of several carbonate platforms started in the early Miocene on this plateau, and although they occurred in low-latitude subtropical waters they are composed mainly of heterozoan organisms. We investigated an upper to distal slope transect drilled during ODP Leg 194 and located close to the Northern Marion Platform. We reconstructed mass accumulation rates of carbonate as well as the evolution in the ratios of carbon and oxygen stable isotopes. Power spectrum analysis of the carbon isotope record revealed the existence of cycles with main frequencies centered around 409 Kyr and 1800 Kyr. We interpret the 409 Kyr cycle as being paced by changes in the eccentricity of the Earth orbit, and we suggest that the 1800 Kyr cycle could be linked to long-term eustatic changes. Finally, on the basis of the timing of changes in mass accumulation rates of carbonate we infer that the strength and direction of oceanic currents affected sedimentation on the Marion Plateau by shifting depocenters of slope sedimentation, a process probably further modulated by sea-level changes. We argue that the evolution and demise of the heterozoan carbonate systems present on the Marion Plateau were controlled mainly by the evolution of strong benthic currents, and that eustasy and water temperature alone did not account for the drowning of the platforms in the mid Miocene.

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“…Many processes have been proposed, such as global anoxic events, tectonic breakup, and excess nutrients (Arthur and Schlanger, 1979;Hallock and Schlager, 1986;Philip and Schlager, 1990;Eberli, 1991). The close relationship between platform drowning and intensification of ocean currents has been proposed for the demise of the Miocene platforms on the Marion Plateau (Isern et al, 2004;John and Mutti, 2005;Eberli et al, 2010). Betzler et al (2009Betzler et al ( , 2013a and Lüdmann et al (2013) document partial platform drowning in the Maldives and propose that, in the Maldives, the drowning of the platforms is the combined product of current activity and nutrient supply.…”

“…Currents affect the water column down to the sediment surface and trigger erosion at the seafloor and migration of large-scale carbonate sand and mud waves. This depositional regime has persisted since the Miocene, and the hypothesis to test is that the onset of current and partial drowning of the carbonate banks were intimately linked (John and Mutti, 2005;Betzler et al, 2009;Eberli et al, 2010). Seismic stratigraphy and facies indicate that the onset of this current was a rapid process and that the intensity of the currents varied through time (Lüdmann et al, 2013).…”

The initiation of the southern central Great Barrier Reef: New multiproxy data from Pleistocene distal sediments from the Marion Plateau (NE Australia)

“…Drift geometries, indicative of strong currents, are effectively distinguished on seismic data in the upper part of the drilled section (Isern et al, 2002). Because there was no barrier to shelter the Marion Plateau from the open ocean, it is reasonable to assume that current patterns on the plateau shifted and/or strengthened in response to global paleoceanographic changes (John and Mutti, 2005). However, a reduction in nutrient supply could represent an alternative explanation for the larger sizes.…”

Sequential and climatic framework of the growth and demise of a carbonate platform: implications for the peritidal cycles (Late Jurassic, North-eastern France)

“…During this period, foramol or heterozoan assemblages (facies IX), assumed to be less productive than chloralgal associations (Mutti & Hallock, 2003), predominated on the platform. A change in the benthic community and the appearance of foramol assemblages was linked locally to a cooling of the sea water and the appearance of mesotrophic conditions (Mutti & Hallock, 2003; John & Mutti, 2005; Halfar et al. , 2006; Coffey & Read, 2007).…”

“…, 2003; Schlager, 2003; Vecsei, 2004; Bachtel et al. , 2005; John & Mutti, 2005; Ehrenberg et al. , 2006; Coffey & Read, 2007).…”