Abstract

Abstract The Miocene represents an interval of marked global change, and this evolution is reflected in carbonate platforms from this epoch. Seismic stratigraphic characterization of high-resolution (ca 60 Hz) 3D seismic data from the Browse Basin, offshore Australia, reveals a middle to upper Miocene three-part seismic stratigraphic subdivision. Each unit consists of several seismic sequence sets and their component sequences. Seismic stratal geometries and seismic facies define a prograding shelf (Langhian and older), a barrier-reef complex with scattered platforms (upper Langhian–early Tortonian), and aggrading and prograding isolated platforms (early Tortonian–Messinian). The data permit description and interpretation of high-fidelity stratigraphic details of the initiation, expansion, termination, and geomorphology of over 100 platforms in this interval. The results reveal that the isolated platforms initiated following the Middle Miocene Climatic Optimum. The succession includes major seismic stratigraphic boundaries and overall patterns of platform growth and demise that correspond roughly with periods of pronounced eustatic change associated with initiation of eastern Antarctic ice sheets. Although invoking a eustatic control for coarse trends may be tempting, mismatch between the numbers and ages of sequences, as well as the variable stacking patterns among contemporaneous platforms regionally, precludes such an interpretation; conversely, some globally recognized eustatic changes do not have a pronounced manifestation in this area. Thus, it appears that the eustatic signal combined with dynamic physical regional processes such as waves, currents, and variable subsidence creates the complex architecture and geomorphology of platforms. These results illustrate how global changes can interact with local controls to create diverse patterns of birth, growth, and demise of carbonate platforms and drive local stratal heterogeneity.

Highlights

  • Isolated platforms represent large-scale edifices constructed largely by the activity of organisms

  • To explore how architectural complexity of isolated carbonate platforms reflects the influences of these controls, this study examines the patterns of initiation, growth, and demise of platforms in a Miocene succession from the Browse Basin (Northwest Shelf, Australia)

  • High-resolution seismic characterization of Middle to late Miocene isolated carbonate platforms of part of the Northwest Shelf, Australia, documents complex a history of birth, growth, and demise

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Summary

Introduction

Isolated platforms represent large-scale edifices constructed largely by the activity of organisms As such, they provide records of any process that influences the flora and fauna or controls the accumulation of sediment derived from their skeletons [1,2,3,4,5,6]. Global climate started to cool [12], and by late Miocene, the Antarctic Ice Sheet started to expand markedly, followed by growth of the northern hemisphere ice sheets and the West Antarctic Ice Sheet in the latest Miocene to Pliocene This buildup of land-based ice sheets led to generally falling sea level [13] and higher amplitudes of change, in the latest Miocene to present.

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