Paleoshorelines and lowstand sedimentation on subtropical shelves: a case study from the Fraser Shelf, Australia

Passos, Tiago; Webster, Jody M.; Braga, Juan C.; Voelker, David C.; Renema, Willem; Beaman, Robin J.; Nothdurft, Luke D.; Hinestrosa, Gustavo; Clarke, Samantha; Yokoyama, Yūsuke; Barcellos, Roberto Lima; Kinsela, Michael A.; Nothdurft, Linda; Hubble, Thomas

doi:10.1080/08120099.2018.1558417

Cited by 10 publications

(7 citation statements)

References 65 publications

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“…coast 39,40 , supports this linkage and indicates active longshore sediment supply and associated dune building occurred during the last-glacial lowstand. Ribó et al 39 also proposed that longshore transport was enhanced at the -60 m shoreline position due to a lack of bedrock headlands restricting northward transport in the region.…”

Section: Sea Level and Sediment Supply Linked To Dune Buildingsupporting

confidence: 55%

Fraser Island (K'gari) and initiation of the Great Barrier Reef linked by Middle Pleistocene sea-level change

et al. 2022

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The eastern Australia coastline is characterized by impressive coastal landforms and an extensive northward-moving longshore drift system that have been influenced by a stable, long-term tectonic history over the Quaternary period. However, the timing and drivers of the formation of two conspicuous landscape features—Fraser Island (K’gari) and the Great Barrier Reef—remain poorly understood. Here we use optically stimulated luminescence and palaeomagnetic dating to constrain the formation of the extensive dunes that make up Fraser Island, the world’s largest sand island, and adjacent Cooloola Sand Mass in southeastern Queensland. We find that both formed between 1.2 Ma and 0.7 Ma, during a global climate reconfiguration across the Middle Pleistocene transition. They formed as a direct result of increased amplitude of sea-level fluctuations associated with increasing global ice volume that redistributed previously stored sediment across the continental shelf. The development of Fraser Island dramatically reduced sediment supply to the continental shelf north of the island. This facilitated widespread coral reef formation in the southern and central Great Barrier Reef and was a necessary precondition for its development. This major reorganization of the coastal sedimentary system is probably not unique to eastern Australia and should be investigated in other passive-margin coastlines.

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Section: Sea Level and Sediment Supply Linked To Dune Buildingsupporting

confidence: 55%

Fraser Island (K'gari) and initiation of the Great Barrier Reef linked by Middle Pleistocene sea-level change

et al. 2022

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“…While coral growth occurs in the South Solitary Islands area, reef-forming accretion is not documented and the rocky reefs documented to date comprise bedrock outcrops [95,96]. It, therefore, appears the ridges in the South Solitary Islands area most likely comprise drowned coastal sand barrier deposits that formed at times of lower sea level during the late-Quaternary glaciations [90,91].…”

Section: South Solitary Islands Case Study Areamentioning

confidence: 99%

“…Platform and patch reef outcrops likely comprise exposed bedrock reefs, overlain by sand sheets deposited during the last glacial transgression [79]. Expansive ridges were documented in the deeper waters of the survey area in 60 to 80 m depth, which are inferred as paleo-shoreline features likely comprised of remnant barrier deposits, such as those documented elsewhere along the Australian continental shelf in similar depths [45,90,91]. Similar paleo-shoreline features have been mapped around the mid-oceanic Lord Howe Island and Balls Pyramid shelves, and are interpreted as potential drowned coral reefs, due to the known accretion of coral reefs around the island shelves in the Holocene and present-day [92][93][94].…”

Section: South Solitary Islands Case Study Areamentioning

confidence: 99%

Techniques for Classifying Seabed Morphology and Composition on a Subtropical-Temperate Continental Shelf

et al. 2019

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In 2017, the New South Wales (NSW) Office of Environment and Heritage (OEH) initiated a state-wide mapping program, SeaBed NSW, which systematically acquires high-resolution (2–5 m cell size) multibeam echosounder (MBES) and marine LiDAR data along more than 2000 km of the subtropical-to-temperate southeast Australian continental shelf. This program considerably expands upon existing efforts by OEH to date, which have mapped approximately 15% of NSW waters with these technologies. The delivery of high volumes of new data, together with the vast repository of existing data, highlights the need for a standardised, automated approach to classify seabed data. Here we present a methodological approach with new procedures to semi-automate the classification of high-resolution bathymetry and intensity (backscatter and reflectivity) data into a suite of data products including classifications of seabed morphology (landforms) and composition (substrates, habitats, geomorphology). These methodologies are applied to two case study areas representing newer (Wollongong, NSW) and older (South Solitary Islands, NSW) MBES datasets to assess the transferability of classification techniques across input data of varied quality. The suite of seabed classifications produced by this study provide fundamental baseline data on seabed shape, complexity, and composition which will inform regional risk assessments and provide insights into biodiversity and geodiversity.

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“…These processes were responsible to shape the seafloor and, in the case of mesophotic habitats and mesophotic reefs, most of shelf morphology reflects features formed during sealevel fall and lowstand, which drowned during the deglaciation process. The development of mesophotic reefs, for instance, is related to submarine morphology resembling features such as drowned reefs (Harris and Davies, 1989;Bridge et al, 2011;Abbey et al, 2013), paleoshorelines (Brooke et al, 2014;Pretorius et al, 2016), hard grounds/terraces (Khanna et al, 2017), cemented dunes and barriers (Brooke et al, 2014;Passos et al, 2019), and incised valleys (Bastos et al, 2022).…”

Section: Discussionmentioning

confidence: 99%

Geomorphological significance of shelf-incised valleys as mesophotic habitats

Oliveira

Lavagnino

Rocha

et al. 2023

Front. Remote Sens.

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Geomorphology provides the core attributes for outlining marine seascapes, once the structural complexity of the seafloor mediates several oceanographic processes and ecosystem services, and is positively associated with biodiversity. Shelf-incised valleys and other prominent meso-scale structures such as reefs and sinkholes have a great potential for the discrimination of benthic habitat groups. Here, we investigate shelf-incised valleys as a mesophotic habitat, by focusing on their geomorphological control in defining distinct habitats in comparison with the flat surrounding area. The study was based on the integration of high-resolution bathymetry data (multibeam echosounder), video imaging, and physical-chemical parameters of the water column. Habitat mapping was conducted using object-based image analysis segmentation and clustering. Principal Component Analysis was used to assess the variables associated with habitat distribution at each morphological region of the valleys. Bathymetric data revealed the presence of 5 shelf-incised valleys and 5 seabed classes were defined as carbonate crusts, Rhodoliths (3 distinct classes) and unconsolidated sediments. A comprehensive habitat map with 17 classes was produced, and 13 are associated with valley´s relief. Extensive rhodolith beds were mapped in the valley flanks/bottom and in the flat areas. Shelf-incised valleys are prominent morphological features that add complexity to the seascape, contrasting with the flat relief that dominates the seascape. The seabed footage obtained in the valleys revealed that their heterogeneous, complex and irregular topography harbors a great diversity of epibionts, such as scleractinian corals, coralline algae, sponges and bryozoans. Most of the variability in the dataset is correlated with salinity, temperature and carbonate sediments, which seem to be the most influential variables over the biological assemblage, together with water depth and seabed slope. Shelf-incised valleys, similarly to submarine canyons, can define a complex mesophotic habitat and sustain distinct biodiversity, and even form mesophotic reefs. These features are the legacy of Quaternary sea-level changes and should be further investigated as important mesophotic habitats.

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Paleoshorelines and lowstand sedimentation on subtropical shelves: a case study from the Fraser Shelf, Australia

Cited by 10 publications

References 65 publications

Fraser Island (K'gari) and initiation of the Great Barrier Reef linked by Middle Pleistocene sea-level change

Fraser Island (K'gari) and initiation of the Great Barrier Reef linked by Middle Pleistocene sea-level change

Techniques for Classifying Seabed Morphology and Composition on a Subtropical-Temperate Continental Shelf

Geomorphological significance of shelf-incised valleys as mesophotic habitats

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