Abstract Storm disturbance and recovery of the peritidal benthic microbial ecosystem occurs as part of the natural climate regime in Shark Bay. However, tropical cyclone and winter storm frequency and intensity are known to be changing due to climate forcing. Presented here is an analysis of the biogeomorphic response of the benthic microbial ecosystem within the intertidal to upper subtidal zone and the beach face coquina deposits of Hamelin Pool, to the passage of Category 3 Severe Tropical Cyclone Olwyn (13 March 2015). Storm effects (initial response to 40 days post‐event) include: erosional sculpting of sediments, mats and structures; deposition and winnowing of sediments; accumulation of mucilaginous products into flocs, slurries and sludges; along with limited development of new coquina deposits in the beach face. Medium (15 months) term observations include: mat recovery and changes with transformation of mucilage deposits into new subtidal gelatinous mats, intertidal transitional mats and low‐elevation microbial structures. Observations suggest that this disturbance had both positive (the floc‐to‐mat biogeomorphic storm response) and negative feedbacks (enhanced bioturbation), which impact the development of stromatolite forming microbial mats and microbialite structures.

The World Heritage microbialites, coquinas, and microbialitic-sediments of Hamelin Pool, Shark Bay, Western Australia, form through complex community and environmental interactions resulting in surficial CO2 sequestration. Predicted climate-change impacts threaten the stability of this setting and the balance of biogeomorphological processes that generate them. In this setting, long-term surficial CO2 sequestration occurs through the combination of biomineralisation, organomineralisation and lithification, which locks atmospheric CO2 into CaCO3 rocks and sediments. Biogeomorphological processes that control the distribution and effectiveness of these mechanisms including biostabilisation, bioconstruction, bioerosion and bioturbation have not been addressed in this setting to date. A three-dimensional biogemorphological mapping unit framework is defined at three locations in Hamelin Pool within the shallow-subtidal to supratidal zones based on historical and recent multiscale datasets. This framework is used to review the complex distribution of geomorphological and biogeomorphological processes. The distribution of lithification within a biogeomorphological process context is examined, and current geological analogue models of microbialite and coquina development are expanded to include biogeomorphological processes. The framework is used to understand the impacts of increased water elevation in response to intensification of the Leeuwin Current during the 2010-2012 Ningaloo Nino event. Potential climate change impacts are identified including reduced intertidal bioconstruction, and a shift from microbialitic structure generation to increased grain generation reducing stromatolite development. Review of the uncertainty of impacts of ocean acidification and temperature shifts on biomineralisation, organomineralisation and lithification processes, crucial to the maintenance of the outstanding universal values in this World Heritage location, suggests urgent research is required.

The Kimberley Bioregion (NW Australia) is characterised by the largest macrotides of any tropical region in the world (about 11 m), frequent tropical cyclones and high-turbidity. Despite these challenging environmental conditions, the region is also known for extensive and diverse intertidal coral reef habitats. While the area has been recognised as an international biodiversity hotspot, it is still poorly investigated compared to other reefal ecosystems in Australia, primarily due to its extreme remoteness and lack of infrastructure. A combination of remote sensing, sub-bottom profiling and associated sedimentological work produced a geodatabase of coral reefs, providing the first detailed geospatial study of coral reefs within the bioregion. More than 800 reefs have been documented and a regional reef geomorphic classification scheme, which includes a new “high intertidal” geomorphic class of reef, was developed. Reef coring shows that reef growth began soon after the post-glacial flooding of the antecedent substrate. High-resolution seismic data, acquired along selected reefs, showed that pre-existing substrate has influenced the successive reef morphology. Global sea-level changes, controlled by ice age fluctuation events, are recorded as successive stages of the reef growth, separated by growth hiatuses. Two seismic reflectors can be distinguished, marking the boundaries between Holocene (Marine Isotope Stage 1, last 12,000, 10-20 m thick) and Last Interglacial (MIS5, 125,000 BP, 12 m thick) reefs and an ancient Neoproterozoic rock foundation.

High-resolution seismic profiles were conducted across the metropolitan area of the Swan River estuary (Perth, Western Australia) to explore the sub-surficial stratigraphic architecture, down to a depth of about 40 m below the river bed. The acoustic profiles revealed a complex system of palaeochannels where three main unconformities (R1, R2, R3) bound as many seismic units (U1, U2, U3), over the acoustic basement. Integrating these data with sediment borehole analysis, LiDAR data and available literature of the geology and stratigraphy of the area, it was possible to determine the development of these stratigraphic units, in response to Late Pleistocene and Holocene sea level fluctuations and conditioned by pre-existing topography and depositional palaeoenvironments during the last similar to 130,000 years. The deepest unit (U3) can be interpreted as the Perth Formation, which consists of interbedded sediments that were deposited in a large palaeo-valley downcutting into the underlying acoustic basement (bedrock: Tamala Limestone and Kings Park Formation), under a fluvial to estuarine setting, existing between similar to 130 and 80 ky BP (in the Last Interglacial).The middle unit (U2), composed of heterogenic fluvial (possibly lacustrine) and estuarine sediments, represents the Swan River Formation. Similarly to the Perth Formation, the formation infills channels incised in older formations and reflects the hydrogeological conditions linked with sea level fluctuation changes during the Last Glacial low stand. Holocene (last similar to 10 ky) fluvial and estuarine deposits form the shallowest uhit (U1). These sediments have a highly variable internal structure, ranging from heavily layered, filling palaeochahnels, to hard and chaotic, atop pre-existing topographic highs. The wave-dominated Swan River system shares several similarities with a number of estuaries worldwide, such as Burrill Lake (NSW, Australia) and Arcachon Lagoon (Aquitaine, France). This research represents the first environmental high-resolution acoustic investigation in the middle reach of the Swan River estuary. (C) 2017 Elsevier B.V. All rights reserved.

The inner shelf Kimberley Bioregion of Northwest Australia is characterised by a macrotidal setting where prolific coral reefs growth as developed around a complex drowned landscape and is considered a biodiversity “hotspot”. High-resolution shallow seismic studies were conducted across various reef settings in the Kimberley (Buccaneer Archipelago, north of Dampier Peninsula, latitude: between 16°40′S and 16°00′S) to evaluate stratigraphic evolution, interaction with different substrates, morphological patterns and distribution. Reef sites were chosen to assess most of the reef types present, particularly high intertidal planar reefs and fringing reefs. Reef internal acoustic reflectors were identified according to their shape, stratigraphic position and characteristics. Two main seismic horizons were identified marking the boundaries between Holocene reef (Marine Isotope Stage 1, MIS 1, last 12ky), commonly 10–20m thick, and MIS 5 (Last Interglacial, LIG, ~120ky, up to 12m thick) and Proterozoic rock foundation over which Quaternary reef growth occurred. Within the Holocene Reef unit, at least three minor internal reflectors, generally discontinuous, subparallel to the reef flat were recognised and interpreted as either growth hiatuses or a change of the coral framework or sediment matrix. The LIG reefs represent a new northernmost occurrence along the Western Australian coast.The research presented here achieved the first regional geophysical study of the Kimberley reefs. Subbottom profiles demonstrated that the surveyed reefs are characterised by a multi-stage reef buildup, indicating that coral growth occurred in the Kimberley during previous sea level highstands. The data show also that antecedent substrate and regional subsidence have contributed, too, in determining the amount of accommodation available for reef growth and controlling the morphology of the successive reef building stages. Moreover, the study showed that in spite of macrotidal conditions, high-turbidity and frequent high-energy cyclonic events, corals have exhibited prolific reef growth during the Holocene developing significant reef accretionary structures. As a result coral reefs have generating habitat complexity and species diversity in what is a biodiversity hotspot.

This study uses information derived from cores to describe the Holocene accretion history of coral reefs in the macrotidal (up to 11 m tidal range) Buccaneer Archipelago of the southern Kimberley coast, Western Australia. The internal architecture of all cored reefs is broadly similar, constituting well-preserved detrital coral fragments, predominantly branching Acropora, in a poorly sorted sandy mud matrix. However, once the reefs reach sea level, they diverge into two types: low intertidal reefs that maintain their detrital character and develop relatively narrow, horizontal or gently sloping reef flats at approximately mean low water spring, and high intertidal reefs that develop broad coralline algal-dominated reef flats at elevations between mean low water neap and mean high water neap. The high intertidal reefs develop where strong, ebb-dominated, tidal asymmetry retains seawater over the low tide and allows continued accretion. Both reef types are ultimately constrained by sea level but differ in elevation by 3–4 m.

The coastal zone off Geraldton in temperate Midwestern Australia was investigated to identify sediment dynamics and sediment budget components of two main embayments. An integrated analysis of hydrodynamics, geomorphology, sediments and habitat data was required to overcome a lack of previous examinations of sediment dynamics in the region. The seaward extent of the nearshore transport system was assessed. An improved understanding of coastal sediment dynamics and its relationship to coastal stability and assets was also achieved. The system is complex, with biogenic sediment input, as well as carbonate dune and river-derived sediments. Coastal erosion at Geraldton is mitigated by nourishment activities which require sand bypassing. Natural and artificial sediment sinks were identified, and are mainly located in the northern embayment where beach erosion is more significant. A dredged shipping channel needed to provide access to port facilities modifies the local sediment dynamics. This study provides new information for managing the Geraldton coast, which may be applicable to similar regions of Western Australia and carbonate coasts elsewhere.

The inshore Kimberley Bioregion of northwest Australia is a macrotidal, low wave energy, frequent cyclones, and high turbidity setting with abundant fringing coral reefs. Here we describe the Holocene development of a sheltered fringing reef at Cockatoo Island in the Kimberley, using data from reef cross-sections subaerially exposed in an iron ore mining pit, seismic profiles across the adjacent contemporary reef, and GIS and ground truth mapping of contemporary reef habitats. Subsidence since the Last Interglacial has provided accommodation for ~13–20m of Holocene reef accretion upon an older, probably Last Interglacial, reef. In the pit cross-sections, the reef initiated at ~9000cal y BP and accreted in a catch-up mode, reaching sea level at ~3000cal y BP, and reef accretion rates varied from 26.8mm/year to 0.8mm/year, averaging ~2mm/year. The catch-up interpretation is supported by the predominance of branching Acropora throughout the Holocene section and the absence of contemporary intertidal indicators such as Porites cylindrica and Millepora intricata. This pattern differs from the otherwise similar mud-rich but mostly microtidal inshore fringing reefs of the Great Barrier Reef, which initiated in the late Holocene on shallow substrates under a stable sea level. The study provides the first Holocene reef growth history for an inshore Kimberley reef within a biodiversity “hotspot”.

Shark Bay World Heritage Area displays a unique Holocene coarse bioclastic (coquina) beach-ridge system in the supratidal environment of Hamelin Pool and L'Haridon Bight hypersaline basins. In Hamelin Pool, E and W shores have different degrees of vulnerability to the usually NW approaching storms. Aerial imagery, GPR profiles, 14C dating and sedimentology were used to delineate a depositional and evolutionary model for beach-ridge deposit in Hamelin Pool E and W shores by assessing internal and external architecture, facies and ages. The onset of the beach-ridge system took place about 5000 14C years BP facilitated by abundant shell supply and falling sea levels, under episodes of high water levels induced by storms. Prograding seaward inclined GPR reflections are the prevailing architectural elements and result from swash-backwash processes in the beachface during elevated water level episodes. An important feature is a diachronous blanket generated by storm-surge events and eolian processes which occasionally develop incipient soils that cap older beach-ridge deposits. During the latest Holocene, marked environmental changes within Hamelin Pool are suggested by change in the depositional style of beach-ridge deposits (complex geometries of spit ridges start to prevail over the seaward inclined reflectors of prograding beachfaces); lower ridge elevations and the occurrence of an erosive period after 1450 14C years BP in the W shore. Although the ages obtained for the ridge sets mapped in both E and W shores of Hamelin Pool are roughly similar, they exhibit differences in sedimentary architecture and coastal morphology as a result of different degrees of vulnerability to storms, and variable reworking by tidal currents, waves and longshore currents which may also be energetic enough during fair-weather conditions to transport sediment in the nearshore environment. A depositional model is proposed where washovers and storm-surge ridges are deposited by overwash episodes at the peak of major storms while berm construction occurs during the waning phase by swash, backwash, overtopping and minor overwashing. This model can be used as an analogue for other coquina deposits in the stratigraphic record providing an example of high-resolution depositional architecture that is useful for reservoir characterization and prediction. Finally, comparison is made with the prograding, well dated system at Telegraph Station, SE Hamelin Pool.

Abstract The Kimberley region is located along the continental margin of northwest Australia and is characterised by unique and complex geology and geomorphology that spans almost 2 billion years. The modern marine environment, considered one of the world's greatest biodiversity hotspots, is significantly influenced by the interaction of long term processes, such as pre-existing rock foundation (Proterozoic Sandstone) and Quaternary subsidence and sea level fluctuations, and short term factors, including macrotides (up to 11 m), high turbidity (related to terrigenous inputs from active rivers), tropical monsoonal climate and warm ocean temperatures.

Abstract The Faure Sill complex is an important geological element in Shark Bay, with a major role in controlling the hypersaline conditions in the southern embayments of Hamelin Pool and L'Haridon Bight. Combining shallow seismic data, lithostratigraphic analysis and radiocarbon dating, the study has provided insights into the Faure Sill in terms of its internal architecture, facies, chronology, bank onset and growth history. The research has provided an understanding of the relationship between the Faure channel bank complex and Wooramel Delta, as part of the wider Gascoyne Delta – Wooramel Bank – Wooramel Delta – Faure Sill system, which stretches for over 200 km along the coast of the Carnarvon Basin.

‘Packaging’ coastal sediment transport into discrete temporal and spatial scale bands is necessary for measurement programs, modelling, and design. However, determining how to best measure and parameterize information, to transfer between scales, is not trivial. An overview is provided of the major complexities in transferring information on coastal sediment transport between scales. Key considerations that recur in the literature include: interaction between sediment transport and morphology; the influence of biota; episodic sediment transport; and recovery time-scales. The influence of bedforms and landforms, as well as sediment-biota interactions, varies with spatio-temporal scale. In some situations, episodic sediment dynamics is the main contributor to long-term sediment transport. Such events can also significantly alter biogeochemical and ecological processes, which interact with sediments. The impact of such episodic events is fundamentally influenced by recovery time-scales, which vary spatially. For the various approaches to scaling (e.g., bottom-up, aggregation, spatial hierarchies), there is a need for fundamental research on the assumptions inherent in each approach.

Coral reefs of the Kimberley Bioregion are seldom studied due to limited accessibility and extreme water conditions, which make management of these vital ecosystems a challenging task. Managing reef resources requires a considerable amount of credible, consistent and continual information. We identified the geographic information system (GIS) approach to be useful in developing an integrated geodatabase by acquiring information from different sources relating to the Kimberley reefs. Based on this approach, the study aimed to create a foundation for the first comprehensive geodatabase of the Kimberley reefs, called ReefKIM. The work included compiling existing spatial and non-spatial data, as well as collecting new data to complete information gaps. The study demonstrates how new technologies can be harnessed to crowdsource data from a wide range of people though a web-based platform. ReefKIM will provide a practical tool for scientists and managers to facilitate better monitoring and sustainable management of these vital natural resources. Moreover, it will support further studies in various disciplines leading to a more detailed understanding of the Kimberley Bioregion reefs.

Within the Faure Sill complex (Shark Bay, Western Australia), a combination of remote sensing analysis, seismic stratigraphy and cores to ground truth, together with radiocarbon dating, demonstrate the interconnection between sediment body morphologies, seagrass related substrates and pre-existing topography and reveal the system as a channel–bank complex. Sea level fluctuations appear to have largely controlled the hydrodynamic conditions of the bank, contributing to each stage of its evolution. 1) Not earlier than 8.5–8.0ka BP, in a lowstand period, after an erosive event of underlying palaeosurfaces, seagrass establishment progressively contributed to initiating bank growth. 2) Around 6800years BP, bank accumulation reached its apex, in conjunction with a rapid sea transgression. 3) During the Late Holocene, succeeding a slow decline to present sea level, bank growth continued to fill available accommodation space and a number of hiatuses, indicating temporal and spatial discontinuities within the process of bank building, are recognised. Average depositional rates of bank building (1.3m/ka) conform to previous estimates derived for seagrass banks but rates are strongly facies dependent, attesting to the dynamic nature of this channel–bank complex. The extensive seagrass meadows are essential for a wide range of aspects of the environment of the Shark Bay area. Not only are they particularly important for the entire shallow benthic ecosystem, but they also had a major role in the partial closure of the southern basins and hence determining the development of hypersaline conditions and associated oolitic microbial and evaporitic facies in Hamelin Pool and L'Haridon Bight. Moreover, this system has a critical role in producing, sequestering and storing organic carbon.

Understanding of the processes regulating sediment transport, accumulation and erosion requires an appropriate mapping of coastal geomorphology, seabed sediments and benthic habitat distribution to allow management issues to be identified, understood and addressed. In this study multibeam echo-sounder data were used to map shallow water geomorphological features and the spatial distribution of benthic habitats, with the support of underwater imagery for ground truthing the acoustic data. At Geraldton, sediment analyses have revealed a dominant biogenic nature, with modern carbonate sedimentation linked to the seagrass and macroalgal carbonate factories colonising these shallow (< 30 m) coastal embayments. Whilst seagrasses are common on sheltered hardgrounds blanketed by fine sand, macroalgae were found on high energy limestone reefs. The distribution of sand bar and sheet systems is regulated by wave induced sediment transport with the influence of pre-existing seabed topography. Exposure to wave energy, seabed geomorphology and sediment characteristics is closely related to the distribution of benthic habitats and sand substrates, highlighting the value of an integrated analysis of these parameters. The capability of multibeam echo-sounder backscatter data to discriminate between seagrass meadows, macroalgal communities and sandy substrates was also evaluated and the acoustic response from the seabed was better explained by considering together seafloor geomorphology and biota type, as both these parameters influence backscatter strength.

The coral reefs of the Kimberley bioregion are situated in an area that is considered a significant ‘biodiversity hotspot’ and are poorly known and of recognised international significance. This paper is a review of ongoing research as part of one of the first geoscientific reef studies of the Kimberley Biozone. Remote sensing, sub-bottom profiling and associated sedimentological work have been employed to produce a regional geodatabase of coral reefs and determine the Holocene internal architecture and growth history of the coral reefs. Satellite image analysis has revealed that fringing reefs in the Kimberley bioregion grow very well and differ geomorphologically from planar reefs both inshore and offshore. The acoustic profiles have depicted multiple reef build-ups, demonstrating the reefs’ long-term resilience. This research has provided a better understanding of the Kimberley reefs and demonstrated their capacity to succeed in challenging environments and generate habitats characterised by high complexity and species diversity.

Three decades after declaration of World Heritage status for Shark Bay new research findings are being reported on the specialised microbial habitats that characterise its hypersaline settings, the composition of microbial communities, tidal flat evolution, stromatolite geochronology and subtidal microbial systems. In the stable, semiarid and evaporative setting within the intertidal–subtidal environment the microbial ecosystem is trapping, binding and biologically inducing carbonate precipitation within laminated stromatolites, non-laminated thrombolitic forms and cryptomicrobial non-laminated forms. Filamentous microbes constitute the dominant group in the blister, tufted and smooth mat types, and coccoid microbes dominate the pustular, colloform and microbial pavement deposit types. Detailed georeferenced substrate mapping has revealed extensive subtidal microbial deposits occupying ~300 km of the total Holocene 1400 km area of Hamelin Pool. The microbial pavement covers 227 km of the subtidal substrate, which together with columnar structures reveals a subtidal microbial habitat that occupies an area several times larger than the area of the intertidal deposits. Oldest dated stromatolite heads are 1915 C years BP, and the overall system was deposited in two stages: the first between 2000 and 1200 and the last from 900 years BP to the present. Slow accretion rates vary from less than 0.1 to 0.5 mm/year. Different internal fabrics were constructed according to their position in relation to the littoral zone by distinct microbial communities, and lateral fabric relations have been established. Evidence of shallowing-upward fabric sequences of microbial origin reflects relative falling sea levels during the late Holocene and is likely useful in ancient environmental interpretation. A new substrate map and depositional history for this distinctive microbial habitat has established the significance of subtidal structures and emphasises the geoscientific importance of Hamelin Pool, especially with respect to early life studies and ancient analogues for understanding microbial activity, deposit characteristics, fenestral fabrics and distribution.

Australia's western margin is adjacent to a low-moderate-relief, semi-arid hinterland extending from northern tropical to southern temperate latitudes. Swell waves occur throughout, and cyclonic storms and tidal influences decline from north to south. The margin is influenced by the poleward-flowing, warm, nutrient-poor Leeuwin Current. There is limited upwelling and localized downwelling of saline water on to the shelf. The North West Shelf (NWS) is an ocean-facing ramp with palimpsest sediments - formed during Marine Isoptope Stage (MIS) 3 and 4; stranded ooids and peloids formed early during the post-Last Glacial Maximum (LGM) sea-level rise - and Holocene particles. Changing oceanography during sea-level rise profoundly affected sediment character.The SW Shelf (SWS) comprises the subtropical sediment-starved Carnarvon Ramp in the north and the incipiently rimmed, flat-topped, steep-fronted Rottnest Shelf in the south. The inner Carnarvon Ramp includes the Ningaloo Reef and hypersaline Shark Bay. The mid ramp is relict or stranded foraminifer-dominated sand, and represents attenuated carbonate production due to downwelling incursions of Shark Bay water on to the ramp; the outer ramp is planktic foraminiferal sand or spiculitic mud. Rottnest Shelf has coralline algal-encrusted hardgrounds, larger symbiont-bearing foraminifers with abundant cool-water elements including bryzoans, molluscs and smaller foraminifers. The SWS is transitional between warm-and cool-water carbonate realms.

High-precision analysis using accelerator mass spectrometry (AMS) was performed upon known-age Holocene and modern, pre-bomb coral samples to generate a marine reservoir age correction value (ΔR) for the Houtman-Abrolhos Archipelago (28.7°S, 113.8°E) off the Western Australian coast. The mean ΔR value calculated for the Abrolhos Islands, 54 ± 30 yr (1 σ) agrees well with regional ΔR values for Leeuwin Current source waters (N-NW Australia-Java) of 60 ± 38 yr. The Abrolhos Islands show little variation with ΔR values of the northwestern and north Australian coast, underlining the dominance of the more equilibrated western Pacific-derived waters of the Leeuwin Current over local upwelling. The Abrolhos Islands ΔR values have remained stable over the last 2896 cal yr BP, being also attributed to the Leeuwin Current and the El Niño Southern Oscillation (ENSO) signal during this period. Expected future trends will be a strengthening of the teleconnection of the Abrolhos Islands to the climatic patterns of the equatorial Pacific via enhanced ENSO and global warming activity strengthening the Leeuwin Current. The possible effect upon the trend of future ΔR values may be to maintain similar values and an increase in stability. However, warming trends of global climate change may cause increasing dissimilarity of ΔR values due to the effects of increasing heat stress upon lower-latitude coral communities.

The Upper Jurassic Arab Formation in the Arabian Peninsula, the most prolific oil-bearing interval of the world, is a succession of interbedded thick carbonates and evaporites that are defined stratigraphically upsection as the Arab-D, Arab-C, Arab-B, and Arab-A. The Arab-D reservoir is the main reservoir in Khurais field, one of the largest onshore oil fields of the Kingdom of Saudi Arabia.In Khurais field, the Arab-D reservoir is composed of the overlying evaporitic Arab-D Member of the Arab Formation and the underlying upper part of the Jubaila Formation. It contains 11 lithofacies, listed from deepest to shallowest: (1) hardground-capped skeletal wackestone and lime mudstone; (2) intraclast floatstone and rudstone; (3) pelletal wackestone and packstone; (4) stromatoporoid wackestone, packstone, and floatstone; (5) Cladocoropsis wackestone, packstone, and floatstone; (6) Clypeina and Thaumatoporella wackestone and packstone; (7) peloidal packstone and grainstone; (8) ooid grainstone; (9) crypt-microbial laminites; (10) evaporites; and (11) stratigraphically reoccurring dolomite.The Arab-D reservoir lithofacies succession represents shallowing-upward deposition, which, from deepest to shallowest, reflects the following depositional environments: offshore submarine turbidity fans (lithofacies 1 and 2); lower shoreface settings (lithofacies 3); stromatoporoid reef (lithofacies 4); lagoon (lithofacies 5 and 6); shallow subtidal settings (lithofacies 7 and 8); peritidal settings (lithofacies 9); and sabkhas and salinas (lithofacies 10). The depositional succession of the reservoir represents a prograding, shallow-marine, reef-rimmed carbonate shelf that was subjected to common storm abrasion, which triggered turbidites.