Module 1a - Modern Coastal and Marginal Marine Enviroments and Facies - Moreton Bay
Modern depositional environments and facies are studies along the subtropical Queensland coast.
Barrier island, tidal inlets, tidal flats, tidal shoals, mouth bars, bayhead deltas, sandy shoals and vegetated mud islands are visited on trips to Moreton Bay or Hervey Bay.
Details of sedimentary structures, bioturbation and sediment body geometry are observed first hand using overflights in small aircraft* and visits to sites by boat.
Short soft-sediment cores and trenches provided a basis for discussions on facies preservation.
Moreton Bay is a large marine embayment between Brisbane and the Gold Coast, Queensland, Australia, protected from most ocean waves by a series of sandy barrier islands (Moreton, North Stradbroke and South Stradbroke Island). Depositional settings within the souther part of Moreton Bay are tide-dominated within a subtropical, mangrove meso-tidal regime. The outboard side of the barrier islands comprises wave-dominated processes with a pronounced longshore drift.
This course visits sites of modern and Pliocene-Holocene sedimentation in the southern part of Moreton Bay. This offers opportunities to visit a diverse range of nearshore and coastal depositional environments.
Examination and discussion of short sediment cores obtained on site will aid in the understanding of key features of these deposits.
Key Objectives:
- Modern coastal depositional environments in a mixed muddy-sandy meso-tidal subtropical setting
- Tidally influenced reach of the Logan River. Pointbar processes. Holocene evolution of the Logan Estuary as an example of transgressive coastal systems
- Mouthbars and bayhead delta, geometry, sediment type, depositional features.
- Bioturbation. How it varies in character between depositional environments, using animal traces to refine depositional interpretations, principles of ichnofacies analysis. Influence of bioturation on reservoir characeteristics.
- Tidal flats, muddy, mixed and sandy. Sedimentary structures and processes, implications for reservoir quality.
- Barrier Island, barrier spit. South & North Stradbroke Islands. Processes of beach accretion and migration. Washovers, beach and upper shoreface facies and processes
- Tidal inlet at Jumpinpin. Observe process at tidal inlet, discuss migration of inlets, preservation potential and reservoir implications
- Flood & Ebb tidal deltas scale, sediment character, bioturbation, preservation potential and recognition of characteristic features
- Lateral variability and correlation length in coastal and shallow marine settings what are suitable reservoir modeling strategies for these facies. What are realistic variogram parameters?
The itinerary will depend in detail on the tides during the course. The timing of courses is always selected to coincide with generally favorable tide times and -ranges to allow maximum access to sites. Transport by 40’ surveyed catamaran sailing vessel on Moreton Bay as a mobile classroom. Transfer by inflatable boats or dinghies to individual sites. Participants will actively sample and describe the sediment at various sites and present their results to the rest of the group. Aerial photography and satellite imagery will be used to maintain an overview of each location in the context of the surrounding facies and environments. Overflights in small aircraft can be included in the itinerary
