There can be no confidence that the “first marine” and “in situ” artefact scatters in the Dampier Archipelago, NW Australia are in their primary archaeological context.

The absence of known prehistoric underwater cultural heritage (UCH) sites on the inner continental shelf of Australia stands in stark contrast to the thousands of sites revealed elsewhere in the world. Two recent claims – Dortch et al. (D2019) and Benjamin et al. (B2020) – put forward the first in situ (i.e., primary context) marine UCH sites in the shallow waters of the Dampier Archipelago, NW Australia, each arguing the stone artefact scatters are at least 7000 years old and are now submerged because of post-glacial sea-level rise. From the data published in D2019 and B2020, we assess the explicit and implicit assumptions and uncertainties of these claims. We include new results of hydrodynamic modelling, new data on coastal erosion and new bathymetric data of northern Flying Foam Passage, leading to a reinterpretation of the archaeology and the sites' sedimentary settings.Whilst the presented lithic material of D2019 and B2020 clearly includes cultural artefacts, we find that the arguments for the sites being of primary context and reflecting early Holocene land surfaces do not stand up to scrutiny and that the available evidence is insufficient to establish the facts. In describing the assumptions and uncertainties in D2019 and B2020, we include example tests to help resolve them. On balance, it appears that these sites are intertidal, and many or all artefacts are likely to have been reworked. These and similar sites would benefit from a thorough appraisal of past and present coastal processes to produce a defensible understanding of site formation processes before it is possible to determine their true nature and significance, noting that, even as secondary sites, they would still inform our understanding of process and change. Such work would support more powerful contributions to submerged prehistory than attempts to seek the first, the earliest, the oldest or deepest.

Pedaro formation, equivalent of Plover sandstone at Savu Island, Outer Banda Arc

Plover Sandstone have been widely known as a good quality of oil and gas reservoir in NW Australia. As the continuity of NW Australia margin, outer Banda Arc become the distribution area of the equivalent of Plover Sandstone units. Therefore, a clear distinction and characterization of equivalent of Plover Sandstones distributed in this area is needed. Thick unit of quartz rich sandstone is scrap out in south Savu Island. Refers to the location where the lithology is found widely distributed, the unit is suggested to be called as Pedaro Formation. The characteristic of the lithology is determined through detailed measured section from two trajectories and laboratory analysis, including fourteen samples of petrography analysis, eight samples of Scanning Electron Microscope (SEM) analysis, and three samples of X-Ray Difraction (XRD) analysis. The lower part of the unit is initiated by braided fluvial conglomerates which gradually become tidal sand flat association of shale layers, coal seams and sandstone insertion. While the upper part of the unit is consisting of thick bedded quartz sandstone with thin siltstone insertion, deposited in the shoreface environment. Those facies association developed at transgressive conditions in the estuarine environment. The characteristic of the sandstone unit of Pedaro Formation is thickly bedded quartz wacke to quartz arenite, white to light grey in color, moderately to very well sorted, mostly mature sand. Pedaro Formation is identified to be deposited at Early Jurassic in interior craton tectonic setting. The characterization of sandstone unit of Pedaro Formation is showing that the unit can be correlate to the equivalent of Plover Sandstone found in Timor. Sandstone unit of Pedaro Formation can play a role as reservoir candidate in petroleum system of Savu and surrounding area.

The stratigraphic record of continental breakup, offshore NW Australia

Continental breakup involves a transition from rapid, fault-controlled syn-rift subsidence to relatively slow, post-breakup subsidence induced lithospheric cooling. Yet the stratigraphic record of many rifted margins contain syn-breakup unconformities, indicating episodes of uplift and erosion interrupt this transition. This uplift has been linked to mantle upwelling, depth-dependent extension, and/or isostatic rebound. Deciphering the breakup processes recorded by these unconformities and their related rock record is difficult because associated erosion commonly removes the strata that help constrain the onset and duration of uplift. We examine three major breakup-related unconformities and intervening rock record in the Lower Cretaceous succession of the Gascoyne and Cuvier margins, offshore NW Australia, using seismic reflection and borehole data. These data show the breakup unconformities are disconformable (non-erosive) in places and angular (erosive) in others. Our recalibration of palynomorph ages from rocks underlying and overlying the unconformities shows: (i) the lowermost unconformity developed between 134.98–133.74 Ma (Intra-Valanginian), probably during the localisation of magma intrusion within continental crust and consequent formation of continent-ocean transition zones (COTZ); (2) the middle unconformity formed between ~134–133 Ma (Top Valanginian), possibly coincident with breakup of continental crust and generation of new magmatic (but not oceanic) crust within the COTZs; and (iii) the uppermost unconformity likely developed between ~132.5–131 Ma (i.e. Intra-Hauterivian), coincident with full breakup of continental lithosphere and the onset of seafloor spreading. During unconformity formation, uplift was focused along the continental rift flanks, likely reflecting landward flow of lower crustal and/or lithospheric mantle from beneath areas of localised extension towards the continent (i.e. depth-dependent extension). Our work supports the growing consensus that the ‘breakup unconformity’ is not always a single stratigraphic surface marking the onset of seafloor spreading; multiple unconformities may form and reflect a complex history of uplift and subsidence during the development of continent-ocean transition.

Nature of the Cuvier Abyssal Plain crust, offshore NW Australia

Magnetic stripes have long been assumed to be indicative of oceanic crust. However, continental crust heavily intruded by magma can also record magnetic stripes. We re-evaluate the nature of the Cuvier Abyssal Plain (CAP), offshore NW Australia, which hosts magnetic stripes and has previously been defined as oceanic crust. We show that chemical data from a basalt within the CAP, previously described as an enriched mid-ocean ridge basalt, could equally be interpreted to contain evidence of contamination by continental material. We also recognize seaward-dipping reflector sequences in seismic reflection data across the CAP. Borehole data from overlying sedimentary rocks suggests that these seaward-dipping reflectors were emplaced in a shallow water (<200 m depth) or subaerial environment. Our results indicate that the CAP may not be unambiguous oceanic crust, but may instead consist of a spectrum of heavily intruded continental crust through to fully oceanic crust. If the CAP represents such a continent–ocean transition zone, then the adjacent unambiguous oceanic crust would be located >500 km further offshore NW Australia than currently thought. This would impact plate tectonic reconstructions, as well as heat flow and basin modelling studies. Our work also supports the growing consensus that magnetic stripes cannot, by themselves, be used to determine crustal affinity.Supplementary material: Enlarged and uninterpreted versions of the magnetic data and seismic reflection lines are available at https://doi.org/10.6084/m9.figshare.c.5332172

NOAA-CFSR Offshore Wind Validation

The wind field at sea is of considerable interest to identify suitable sites and for designing offshore wind energy production facility. However, the reliability of wind information suffers from the relative scarcity of offshore wind measurements to validate the wind models used in assessments. This paper presents a comparison of the publicly available NOAA-CFSR global re-analysis data set against offshore wind measurement collected in West Africa, Mediterranean Sea, Barents Sea and NW Australia, with the goal to investigate — in widely different meteorological conditions — the overall model reliability, in term of statistical indices of performance: Moreover, an attempt has been made to ascertain the representative averaging duration of model wind and the reliability of engineering formulas used to correlate wind of different averaging durations.

Salt in the Vulcan sub-basin, NW Australia: observations from high-quality 3D seismic data and implications for palaeogeography

The Vulcan sub-basin is one of the few places in Australia where tectonic features (i.e. diapirs) associated with a mobile substrate can be found. In this presentation one of these features, the Paqualin diapir, and its environs will be described and discussed using the new regional NOVAR MC3D prestack depth migrated seismic dataset. The extent of the NOVAR MC3D seismic dataset makes it possible, for the first time, to integrate the observation of c. 600m of interbedded halite and anhydrite in the Paqualin-1 well, local fault geometries indicative of the movement of a mobile layer and regional tectonic features consistent with the presence of a mobile substrate. In this presentation the observations will be integrated with global analogues, regional palaeogeographic interpretations to refine models for the origin and spatiotemporal distribution of mobile layers in the Vulcan sub-basin.

A Chemometry of Aldrovanda vesiculosa L. (Waterwheel, Droseraceae) Populations

The genus Aldrovanda is a Palaeogene element containing a single extant species, Aldrovanda vesiculosa L. This aquatic carnivorous herb has a very wide range of distribution, natively covering four continents; however, it is a critically endangered aquatic plant species worldwide. Previous studies revealed that A. vesiculosa had an extremely low genetic variation. The main aim of the present paper is to explore, using chemometric tools, the diversity of 16 A. vesiculosa populations from various sites from four continents (Eurasia, Africa, Australia). Using chemometric data as markers for genetic diversity, we show the relationships of 16 A. vesiculosa populations from various sites, including four continents. Phytochemical markers allowed the identification of five well-supported (bootstrap > 90%) groups among the 16 populations sampled. The principal component analysis data support the idea that the strongly related African (Botswana) and Australian (Kimberley, NT, NW Australia) populations are the most distant ones, separated from the European and Asian ones. However, considering the five Australian populations sampled, three are nested within the Eurasian group. The chemometric data are correlated positively with the geographical distances between the samples, which suggests a tendency toward isolation for the most distant populations.