Pilbara Region Research Articles

Non-Linear Modes of Narrative in the Disruption of Time and Genre in Ambelin Kwaymullina’s <em>The Interrogation of Ashala Wolf</em>

Non-Linear Modes of Narrative in the Disruption of Time and Genre in Ambelin Kwaymullina’s <em>The Interrogation of Ashala Wolf</em>

Using Genetics to Evaluate the Success of a Feral Cat (Felis catus) Control Program in North-Western Australia.

Simple SummaryThe management of invasive species is a major challenge for the conservation of biodiversity globally. One technique that has been widely used to control feral cats (Felis catus) and red foxes (Vulpes vulpes) in Western Australia is the aerial broadcast of toxic baits, but assessing its efficacy can be difficult. Here, we report on a method of evaluating the effectiveness of this method for the abatement of feral cats using genetic analysis techniques. However, our results were unable to provide robust evidence that, over a five-year program, baiting had a detrimental impact on both genetics and demography in this population, and the results were not significant. Monitoring the impact of control programs in this way may provide valuable information to managers on the effectiveness of their management strategy, but further refinement of the methodology is recommended.The feral cat has been implicated in the decline and extinction of many species worldwide and a range of strategies have been devised for its control. A five-year control program using the aerial broadcast of toxic Eradicat® baits was undertaken at Fortescue Marsh in the Pilbara region of north-western Australia, for the protection of biodiversity in this important wetland area. This program has been shown to have had a significant detrimental effect on cats in this landscape, but the long-term impact is difficult to ascertain. We assessed population genetics across three cohorts of feral cats sampled as part of the control program. We also compared cat populations in natural habitats and around human infrastructure. A key challenge in any study of wild animal populations is small sample sizes and feral cats are particularly difficult to capture and sample. The results of this study superficially appear to suggest promising trends but were limited by sample size and many were not statistically significant. We find that the use of genetic techniques to monitor the impact of invasive species control programs is potentially useful, but ensuring adequate sample sizes over a long enough time-frame will be critical to the success of such studies.

The genesis of Carlow Castle: A unique Australian orogenic Cu-Co-Au deposit in the Archean Pilbara Craton

Carlow Castle is a Cu-Co-Au deposit situated within the western Pilbara Craton of Western Australia. Whilst Carlow Castle is the oldest discovered copper deposit in the Pilbara region, having been ...

Subsurface seismic imaging using drill bit noise

SummaryAcoustic signal generated by drill bit cutting action in the borehole can be recorded passively by geophones on the surface and used to produce an image of the subsurface under the geophone array. A single pilot trace is commonly recorded on the drill string and used to convert geophone recordings to equivalent reverse vertical seismic profile data. If there is no pilot measurements on the drill string, seismic interferometry can be used to move continuous sources of energy from the bottom of the borehole to the surface and use conventional seismic methods to image the subsurface.In this study, we recorded the noise coming from drilling operation for several shallow wells over the surface of a small iron ore prospect in Pilbara region of Western Australia. As pilot measurements were not available, we used seismic interferometry to produce virtual shots on the surface. We then migrated virtual data generated along one receiver line for one deep well and four shallower wells over the line. We saw that only deep well with longer drilling time can produce a seismic image with coherent events that are comparable to 3D surface seismic data.

'Having a Quiet Word': Yarning with Aboriginal Women in the Pilbara Region of Western Australia about Mental Health and Mental Health Screening during the Perinatal Period.

Despite high rates of perinatal depression and anxiety, little is known about how Aboriginal women in Australia experience these disorders and the acceptability of current clinical screening tools. In a 2014 study, the Kimberley Mum’s Mood Scale (KMMS) was validated as an acceptable perinatal depression and anxiety screening tool for Aboriginal women in the Kimberley region of Western Australia. In the current study, we explored if it was appropriate to trial and validate the KMMS with Aboriginal women in the Pilbara. Yarning as a methodology was used to guide interviews with 15 Aboriginal women in the Pilbara who had received maternal and child health care within the last three years. Data were analysed thematically, the results revealing that this cohort of participants shared similar experiences of stress and hardship during the perinatal period. Participants valued the KMMS for its narrative-based approach to screening that explored the individual’s risk and protective factors. While support for the KMMS was apparent, particular qualities of the administering health care professional were viewed as critical to the tool being well received and culturally safe. Building on these findings, we will work with our partner health services in the Pilbara to validate the KMMS with Pilbara Aboriginal women.

Depth‐Resolved Groundwater Chemistry by Longitudinal Sampling of Ambient and Pumped Flows Within Long‐Screened and Open Borehole Wells

AbstractDepth‐resolved chemistry samples are critical to a wide range of groundwater investigations. If a well intersects zones of variable concentrations, a pumped sample is a composite of the inflows, which mix in the well. Where discrete concentrations are required, excessive mixing makes samples less useful and potentially misleading. However, installations for depth‐discrete sampling are expensive, particularly for regional studies, so sometimes there is incentive to use existing infrastructure designed for other purposes (e.g., supply wells). This paper shows how the resolution of groundwater chemistry derived from long‐screened and open borehole wells can be improved by measuring and sampling the in‐well vertical flow regimes in ambient (unpumped) and/or pumped conditions. The ambient flow regime, driven by a natural vertical head gradient, is shown to be particularly useful to sample groundwater native to defined inflow zones (head in the zone > head in the well) and avoid zones impacted by the invasion of intraborehole flow (head in the zone < head in the well). Depth‐specific samples are interpreted either as native groundwater from a discrete source, subject only to analytical error, or a mixture from multiple sources that can be deconvolved, incorporating error in both flow and concentration measurements. Depth‐resolved age tracers (chlorofluorocarbons, 14C, and He) in groundwater from three supply wells are verified with samples from a multidepth nest of piezometers. Results show old groundwater at all depths and the simultaneous occurrence of young water at shallower depths in undisturbed dual‐porosity fractured aquifers in the Pilbara region of Western Australia.

Highly promiscuous paternity in mainland and island populations of the endangered Northern Quoll

AbstractPolyandry is a commonly utilized strategy in mammalian reproductive systems, where females engage in mating with multiple males to increase either the genetic diversity or quality of their offspring. Some species also exhibit male semelparity, a peculiar life‐history trait where all or most males within a population begin to die following mating. The northern quoll (Dasyurus hallucatus) possesses both of these reproductive adaptations, and females of this species may produce up to eight young in a single litter. Here we aimed to quantify whether there was any difference in female quolls’ choice of male sires between two genetically distinct populations located in the Pilbara region of Western Australia (one mainland‐dwelling and one island‐dwelling population). The total parentage exclusion probability was 0.9999 for excluding a candidate parent from parentage, given the genotype of a known mother. Overall, we found that every litter had young resulting from multiple males. In some litters, a different male fathered every offspring. Thus, northern quolls demonstrated a greater level of polyandry than has previously been detected in marsupials. Furthermore, females from the less genetically diverse island population exercised mate choice and preferentially bred with males that were, on average, 20% smaller than a different male randomly sampled from the island. There was no detectable difference with regard to male sire body size in the mainland population, indicating a difference of selective pressures for the two populations.

Scratching the surface of subterranean biodiversity: Molecular analysis reveals a diverse and previously unknown fauna of Parabathynellidae (Crustacea: Bathynellacea) from the Pilbara, Western Australia

Like other crustacean families, the Parabathynellidae is a poorly studied subterranean and aquatic (stygobiontic) group in Australia, with many regions of available habitat having not yet been surveyed. Here we used a combined approach of molecular species delimitation methods, applied to mitochondrial and nuclear genetic data, to identify putative new species from material obtained from remote subterranean habitats in the Pilbara region of Western Australia. Based on collections from these new localities, we delineated a minimum of eight and up to 24 putative new species using a consensus from a range of molecular delineation methods and additional evidence. When we placed our new putative species into the broader phylogenetic framework of Australian Parabathynellidae, they grouped with two known genera and also within one new and distinct Pilbara-only clade. These new species significantly expand the known diversity of Parabathynellidae in that they represent a 22% increase to the 109 currently recognised species globally. Our investigations showed that sampling at new localities can yield extraordinary levels of new species diversity, with the majority of species showing likely restricted endemic geographical ranges. These findings represent only a small sample from a region comprising less than 2.5% of the Australian continent.

Improving links between environmental accounting and scenario‐based cumulative impact assessment for better‐informed biodiversity decisions

Abstract Increasing attention is being given to understanding how intensifying human activities combine over space and time to influence persistence of biodiversity. Two types of biodiversity assessment in particular are attracting growing interest: one focused on understanding past‐to‐present change (environmental accounting) and another focused on understanding likely present‐to‐future changes under proposed scenarios of future actions (cumulative impact assessment of scenarios). Here we highlight the potential benefits of improving the links between environmental accounting and scenario‐based cumulative impact assessment for biodiversity, using a case study for subterranean fauna in the Pilbara region of Australia. Using a flexible and comprehensive model‐based analytical approach, we assessed expected change in biodiversity persistence given past development, and likely change to 2100 under a proposed development scenario for the region. Our assessment shows both the times (2005–2015) and places (Fortescue sub‐region) where development activities are likely to have most strongly influenced long‐term biodiversity persistence for subterranean fauna in the Pilbara region. Although mining development has often occurred in areas that have a high value for subterranean fauna diversity, our linked environmental accounting and cumulative impact assessment suggest relatively modest impacts on long‐term persistence for this component of biodiversity. Synthesis and applications. Our study provides an effective demonstration of the capacity and potential benefits of better linking environmental accounting with scenario‐based cumulative impact assessment. Improving the links between these two perspectives on biodiversity assessment will create benefits for both, providing a consistent basis for cumulative impact assessments and enhancing the usefulness of environmental accounting.

Characterisation of phosphorus and other impurities in goethite-rich iron ores – Possible P incorporation mechanisms

Phosphorus is one of the most deleterious elements in iron ore as it follows iron during downstream reduction processes, forming iron phosphides that make steel brittle. Excess phosphorus increases the cost of steelmaking and the steel industry has placed an upper limit of 0.07–0.08 wt-% P on the iron ore feed.Goethite grains containing high levels of phosphorus are abundant in many iron ores and can be difficult to remove without also discarding valuable iron-containing units. The goethite forms during supergene metasomatic enrichment of BIF-derived ores and the phosphorus is typically associated in goethite with other impurity elements such as Si and Al.The current study focusses on determining the distribution and association of phosphorus within goethite present in a high-P Brockman type iron ore from the Pilbara region of Western Australia. Detailed characterisation of the chemistry and mineralogy of the goethite-rich ore was conducted using XRF, optical microscopy and EPMA to determine the distribution of phosphorus and other impurity elements. Using this knowledge, we speculate on the possible P substitution mechanisms in goethite. The latter has important implications in designing strategies for beneficiating high-P goethitic iron ores.

Timing and development of sedimentation of the Cleaverville Formation and a post‐accretion pull‐apart system in the Cleaverville area, coastal Pilbara Terrane, Pilbara, Western Australia

AbstractIn the Cleaverville area of Western Australia, the Regal, Dixon Island, and Cleaverville Formations preserve a Mesoarchean lower‐greenschist‐facies volcano‐sedimentary succession in the coastal Pilbara Terrane. These formations are distributed in a rhomboidal‐shaped area and are unconformably overlain by two narrowly distributed shallow‐marine sedimentary sequences: the Sixty‐Six Hill and Forty‐Four Hill Members of the Lizard Hills Formation. The former member is preserved within the core of the Cleaverville Syncline and the latter formed along the northeast‐trending Eighty‐Seven Fault. Based on the metamorphic grade and structures, two deformation events are recognized: D1 resulted in folding caused by a collisional event, and D2 resulted in regional sinistral strike‐slip deformation. A previous study reported that the Cleaverville Formation was deposited at 3020 Ma, after the Prinsep Orogeny (3070–3050 Ma). Our SHRIMP U–Pb zircon ages show that: (i) graded volcaniclastic–felsic tuff within the black shale sequence below the banded iron formation in the Cleaverville Formation yields an age of (3 114 ±14) Ma; (ii) the youngest zircons in sandstones of the Sixty‐Six Hill Member, which unconformably overlies pillow basalt of the Regal Formation, yield ages of 3090–3060 Ma; and (iii) zircons in sandstones of the Forty‐Four Hill Member show two age peaks at 3270 Ma and 3020 Ma. In this way, the Cleaverville Formation was deposited at 3114–3060 Ma and was deformed at 3070–3050 Ma (D1). Depositional age of the Cleaverville Formation is at least 40–90 Myr older than that proposed in previous studies and pre‐dates the Prinsep Orogeny (3070–3050 Ma). After 3020 Ma, D2 resulted in the formation of a regional strike‐slip pull‐apart basin in the Cleaverville area. The lower‐greenschist‐facies volcano‐sedimentary rocks are distributed only within this basin structure. This strike‐slip deformation was synchronous with crustal‐scale sinistral shear deformation (3000–2930 Ma) in the Pilbara region.

Machine learning assisted geological interpretation of drillhole data: Examples from the Pilbara Region, Western Australia

In minerals exploration, routine drilling is performed and the data logged from these drillholes, including lithological composition, assays, and downhole geophysical measurements such as natural gamma logs, are used to create geological interpretations of the strata within each drillhole. A 3D geological model can be created by identifying corresponding stratigraphic boundaries within multiple drillholes. These models can be used for understanding the formation and the mineral endowment of a deposit.We introduce a system for producing stratigraphic interpretations of iron ore exploration drillholes in the Pilbara region in Western Australia. The algorithm firstly classifies each data modality independently for each geological interval, for example 2 m, with classification results for each stratigraphic unit as output. These classifiers, for geological logging, assays, gamma logs, were trained on historical datasets over a wide range of strata in the Pilbara. The influence of each classifier can be adjusted according to the user’s preference, and a novel optimisation algorithm incorporates known geological features such as dykes, faults and thicknesses of various stratigraphic units, to objectively create the best fit interpretation of the geology. A geologist can then adjust this interpretation to include local knowledge.Manual interpretations of 396 drillholes from a high-grade iron ore deposit are compared to interpretations of the same hole prepared by the algorithm. Analysis of interval-by-interval interpretations, and basement geology demonstrate that without any human input, similar interpretations are produced while reducing manual effort.

Plundering Carlow Castle: First Look at a Unique Mesoarchean-Hosted Cu-Co-Au Deposit

Abstract Economically significant and geologically complex veined Cu-Co-Au mineralization was recently discovered at Carlow Castle in the Pilbara region of northwestern Western Australia. The inferred resource estimate for Carlow Castle as of March 2019 is 7.7 million tonnes (Mt) at 1.06 g/t Au, 0.51% Cu, and 0.08% Co, making it one of Australia’s most significant known Cu-Co-Au deposits. Here we provide the first account and scientific analysis of Carlow Castle. This analysis suggests that it is a hydrothermal Cu-Co-Au deposit, with mineralization hosted in sulfide-rich quartz-carbonate veins. The ore is hosted in veins that occur within a pervasively chloritized shear zone through the regionally significant Regal thrust. At Carlow Castle the shear zone associated with this thrust occurs within the Ruth Well Formation, an Archean mafic volcano-sedimentary sequence. Within the mineralized veins the dominant ore minerals are pyrite (FeS2), chalcopyrite (CuFeS2), chalcocite (Cu2S), cobaltite (CoAsS), and electrum (Au,Ag). The genesis of the Carlow Castle deposit is still under investigation; however, the origin of the Cu-Co-Au mineralization is most likely related to the migration of metalliferous fluids along the Regal thrust. Based on Carlow Castle’s stratigraphic position within the Pilbara craton and the craton’s relative stability since the Archean, an Archean age of mineralization is most likely. The distinct Cu-Co-Au enrichment at Carlow Castle makes it unique among Archean ore deposits generally, as the majority of Cu-Co deposits are of maximum Proterozoic age. Therefore, understanding the genesis of the Carlow Castle deposit has important implications for understanding the unique processes through which Cu-Co-Au mineralization outside of basin-hosted ore deposits may be formed, particularly in Archean terranes.

Geomorphic and hydrological controls on groundwater dolocrete formation in the semi‐arid Hamersley Basin, northwest Australia

AbstractGroundwater dolocretes may exert an important geomorphic control on landscape evolution within sub‐humid to arid regions. However, the geomorphic and hydrogeological settings of dolocrete remain poorly described. The hydrochemical conditions of dolomite precipitation in groundwater environments are also not well known. Classic models of dolocrete formation explain dolomite precipitation from highly evolved groundwaters at the terminus of major drainage but do not explain dolocrete distributed in regionally elevated landscapes, upgradient of major drainage. This study investigated the mineralogy, micromorphology and stable carbon and oxygen isotope compositions of three dolocrete profiles within a regionally elevated sub‐basin of the Hamersley Ranges in the Pilbara region of northwest Australia. We sought to establish the environmental and hydrochemical conditions and present a model for dolocrete formation. We found that dolocrete formed within zones of emerging groundwater under saline‐evaporitic conditions within internally draining sub‐basins, most likely during the Late Miocene and Pliocene. Saline‐evaporitic conditions were indicated by: (i) the mineralogy, dominated by dolomite, palygorskite and smectite; (ii) desiccation features and the presence of phreatic and vadose cements, indicative of a shallow fluctuating water table, and; (iii) dolomite δ18O values (median = –5.88 ‰). Dolomite precipitation was promoted by evaporation and carbon dioxide degassing from shallow magnesium (Mg)‐rich groundwater. These factors appear to have been the major drivers of dolocrete development without a requirement for significant down‐dip hydrochemical modification. Primary dolomite precipitation was possible due to the presence of microbial extracellular polymeric substances (EPS). EPS provided negatively charged nucleation sites, which bound Mg2+, overcoming kinetic effects. High microbial activity within groundwater systems suggest these processes may be important for dolocrete formation worldwide and that groundwater dolocretes may be more pervasive in landscapes than currently recognized. © 2019 John Wiley & Sons, Ltd. © 2019 John Wiley & Sons, Ltd.

Albinism in Dasyurus species – a collation of historical and modern records

A new record of an albino marsupial, the northern quoll (Dasyurus hallucatus), is described and placed in the context of 10 records since 1874 from all four Australian quoll species. Of the 10 previous records, one was D. hallucatus, seven are likely to be D. viverrinus, one D. maculatus and one unknown. The recent record comprises the live capture of a healthy adult female northern quoll from the Pilbara region of Western Australia. Despite the rarity and likely deleterious nature of the albino condition, this animal appeared to be in good health, carrying eight pouch young, and was released at location of capture following tissue sampling for DNA analysis.

Concentrations of some metals in the nearshore marine sediments of Western Australia's Pilbara Region.

Concentrations of arsenic, nickel and chromium in sediments of the nearshore Pilbara Region of Western Australia's mid -north coast have caused concerns to regulators issuing ocean disposal permits for many years. A meta-analysis of data from a large number of surveys, conducted in support of permit applications over many years and across hundreds of kilometres of coastline, shows that, when assessed as total metal concentrations, chromium and nickel occur routinely at concentrations above those recommended as screening triggers by national guidelines and arsenic more rarely. Arsenic was concentrated in surface sediments, consistent with an organic origin. Concentrations of nickel and chromium were higher in deeper sediment layers, consistent with a natural geological origin. However, sediment particle sizing was a major determinant of total metal concentrations of all three metals, and bioavailability was always much lower and within recommended guidelines. Past dredging activity for channels and berths in the large ports of the Pilbara has most likely led to an elevation of fine fractions of surface sediments within operating port areas, when compared to the undisturbed surrounding areas, and may also have increased the proportion of sediment from deeper substrates at the surface. Whilst total concentrations of chromium and nickel commonly exceed screening guidelines throughout the nearshore Pilbara Region, their bioavailability was low and these metals present a little threat to biota.

Crown-of-thorns starfish impede the recovery potential of coral reefs following bleaching

High densities of the corallivorous crown-of-thorns starfish (CoTS; Acanthaster sp.) have occurred throughout the Indo-Pacific often resulting in widespread coral loss. Whilst CoTS have previously been recorded at Barrow and the Montebello Islands, in the Pilbara offshore bioregion of northwestern Australia, their densities were relatively low. Outbreak densities of CoTS have been described as the level at which the rate of coral consumption by the starfish is equal to or greater than rate at which the coral grows. In 2014, we recorded densities as high as 320 ± 58 CoTS ha−1 in the region which is well above recognised outbreak densities. Whilst there is little terrestrial runoff and agriculture in the Pilbara region, both temperature and chlorophyll-α levels appear to be sufficient to allow a high degree of CoTS larval success in most years. The region was subjected to anomalously high water temperatures during the summers of 2010–2011 and particularly 2012–2013 which resulted in the mortality of almost 70% of live coral. We hypothesise that the high densities of CoTS observed are a result of CoTS responding to a reduced food supply and aggregating around the remaining live coral resulting in outbreak densities rather than a significant increase in the number of CoTS in the area. The small amount of remaining live coral is concentrated in a few areas and this, combined with high densities of CoTS in these areas, suggest that CoTS represent a significant threat to the recovery of the coral communities of the region.

Water availability drives the effectiveness of inorganic amendments to increase plant growth and substrate quality

In a time when global climate variability threatens the sustainability and productivity of arid ecosystems, the development of effective strategies to recover and protect soil resources and biota is crucial for the survival of these landscapes. With 20% of arid systems degraded and estimates of up to 10 Mha of land degrading each year, this issue is of global importance. In the semi-arid Pilbara region of north-west Western Australia, climatic projections suggest reductions in annual rainfall and high unpredictability of rain events. However, as these ancient landscapes are already degraded due to meteorological processes and anthropogenic activities, such as mining, the rehabilitation of this land is severely challenging. Here, we present a case study that examines, under different rainfall scenarios, the effect of two inorganic amendments (gypsum and urea) on substrate quality and growth of two plant species (Acacia inaequilatera and Triodia wiseana) native to the Pilbara region. Through an extensive glasshouse experiment, two doses of inorganic amendments were tested and compared to unamended mining waste (overburden) substrates extracted from an iron-ore mine of moderately alkaline pH and low nitrogen status. Our results showed that the addition of urea (nitrogen-based fertiliser) produced a three-fold increase of plant growth in A. inaequilatera and up to a 25-fold increase in T. wiseana compared to unamended substrates when grown under the higher watering regime but this effect was not evident in the lower water regimes. The inorganic amendments decreased pH and increased EC, total nitrogen and N-mineralisation but did not have a significant effect on soil microbial activity. Overall, water was the dominant driver for determining the effectiveness of the substrate amendments to improve the quality of mine waste substrates and increase plant growth. This study contributes to unravelling the role of inorganic amendments in post-mining rehabilitation in arid regions faced with climate change.

Demography of the northern quoll (Dasyurus hallucatus) in the most arid part of its range

Abstract The northern quoll (Dasyurus hallucatus) is a carnivorous marsupial that has suffered severe population declines over the last 50 years and is now listed as Endangered. The Pilbara region of Western Australia is a semi-arid area that represents an extreme of the northern quoll’s range. The overall objective of this study was to assess population characteristics of northern quolls at two rocky sites in the Pilbara, focusing on body condition, reproductive timing, population size, and sex-specific survival. We interpret these in the context of variation in habitat quality and the harsh climate. We found that reproduction occurred later in the year than in populations at more mesic locations where quolls have been previously studied, although their life history and demography were otherwise similar to that in other parts of their range. Contrary to our expectations, post-mating mortality of males was not complete. Population sizes differed between sites, suggesting that these rocky habitats varied in habitat quality. We suggest that local population size estimates can guide decisions on the relative importance of sites to ensure the long-term conservation of the species, given impacts of mining and the imminent invasion of introduced cane toads (Rhinella marina).

The Archaean to Proterozoic igneous rocks of the Pilbara region, Western Australia –internationally significant geology of a globally unique potential geopark

The Pilbara region of Western Australia, covering some 500 km × 500 km, provides a diversity of Archaean to Proterozoic igneous rocks in a relatively compact area that records a younging southward crustal history of igneous activity, sedimentation, early life, tectonics, and metamorphism from the Archaean (3.6–2.7 Ga) to Proterozoic (2.5–1.8 Ga). The igneous rocks are variable in age, types of rocks, and mode of occurrence and, throughout the Precambrian, record varying igneous rock activity that appear related to several age-related geological settings: to north, the Archaean Pilbara Craton consists of a granitoid-and-greenstone complex; in the central region, there are Proterozoic sequences of volcanic rock, volcaniclastic rock, ironstone, chert, dolomite, shale, and intrusive dolerite sills and cross-cutting dolerite dykes; to the south, there are Proterozoic shale, dolomite, and chert with isolated granitic batholiths. Igneous activity begins in the Archaean with mafic and ultramafic volcanism alternating with sedimentation, and then granitoid cratonisation. This was followed by Proterozoic volcanic crustal accretion with mafic volcanic and volcaniclastic rocks, and by dolerite and gabbro sill and dyke intrusions, ending with isolated granite batholithic intrusions.Igneous rocks in the Pilbara region are diverse: komatiite; mafic volcanic/volcaniclastic rocks; basalt; tuff/volcanic breccia/accretionary lapilli; dolerite, gabbro, leucogabbro, pegmatitic gabbro, granite, and adamellite; xenolithic dolerite/gabbro; andesite, dacite, rhyodacite, rhyolite; granitoids: adamellite, monzogranite, syenogranite, granodiorite, tonalite, granite; granophyre; felsic dykes; and felsic porphyry. They are expressed as granitoid batholiths, komatiite and basalt sheets/lenses, mafic volcanic/volcaniclastic rocks in sheets, sills of dolerite, gabbro, ultramafic rocks, and diorite, dykes of dolerite, gabbro, and felsic rocks, structurally-oriented dolerite dyke swarms, tuff/volcanic breccia/accretionary lapilli in sheets/lenses, sheets of dacite, rhyodacite, rhyolite, and andesite, gabbroic plugs, apophyses, and a variety of host-rock to xenolith relationships. Today, the Pilbara region is arid, hence outcrop is excellent and many of these geological features are well exposed. The diversity of Archaean to Proterozoic igneous rocks in a relatively compact and well-exposed area and qualifies it as a globally unique potential Precambrian igneous-rock geopark.