Authors: Hinestrosa, G., Webster, J.M., Beaman, R.J., Anderson, L., Barrett, S.J.
Publication: 12th International Coral Reef Symposium, 9-13 July 2012. Coral Reef Studies Centre of Excellence, Cairns, Australia
Understanding of the past development of the Great Barrier Reef (GBR) provides an important framework with which to better predict the future of modern carbonate systems, especially in response to abrupt climate changes. This study takes a seismic-stratigraphic approach and investigates the geomorphic response of the submerged GBR shelf edge reefs to past sea level and climate changes since the Last Glacial Maximum (LGM).
Based on new high-resolution 2D seismic data (Topas, Sparker), constrained by other data sets (multibeam bathymetry, IODP Exp. 325 core and petrophysical data), we investigated the 3D architecture of the shelf edge at Hydrographers Passage.
We identified three distinct seismic units, bounded by prominent reflectors, in sub-bottom profiles across the inner lagoon to the reef edge. Within each of these units, seismic facies were recognized based on signal elements such as clinoform associations, character (mute, chaotic, continuous), attributes (e.g. amplitudes), and reflector shape.
These facies constitute the expression of specific depositional features (e.g. bedding patterns, reef growth, erosion, karst) and of the physical properties of the reef and associated sediments, and are fundamental to understanding the evolution of each broader seismic unit. The high density of seismic data at Hydrographers Passage allow for a 3D reconstruction of the system’s architecture, and constitutes an important starting point for 3D numerical reef modelling.
We present initial modelling results and discuss their broader implications for understanding the main geological and oceanographic processes that have influenced the evolution of the shelf edge since the LGM.