A new period of volcanogenic massive sulfide formation in the Yilgarn: A volcanological study of the ca 2.76 Ga Hollandaire VMS deposit, Yilgarn Craton, Western Australia

The Archean Hollandaire volcanogenic massive sulfide deposit is a felsic–siliciclastic VMS deposit located in the Murchison Domain of the Youanmi Terrane, Yilgarn Craton, Western Australia. It is hosted in a succession of turbidites, mudstones and coherent rhyodacite sills and has been metamorphosed to upper greenschist/lower amphibolite facies and includes a pervasive S1 deformational fabric. The coherent rhyodacitic sills are interpreted as syndepositional based on geochemical similarities with well-known VMS-associated felsic rocks and similar foliations to the metasediments. We offer several explanations for the absence of textural evidence (e.g. breccias) for syn-depositional origins: 1) the subaqueous sediments were dehydrated by long-lived magmatism such that no pore-water remained to drive quench fragmentation; 2) pore-space occlusion by burial and/or, 3) alteration overprinting and obscuring of primary breccias at contact margins. Mineralisation occurs by sub-seafloor replacement of original host rocks in two ore bodies, Hollandaire Main (~125 x >500 m and ~8 m thick) and Hollandaire West (~100 x 470 m and ~5 m thick), and occurs in three main textural styles, massive sulfides, which are exclusively hosted in turbidites and mudstones, and stringer and disseminated sulfides, which are also hosted in coherent rhyodacite. Most sulfides have textures consistent with remobilisation and recrystallisation. Hydrothermal metamorphism has altered the hangingwall and footwall to similar degrees, with significant gains in Mg, Mn and K and losses in Na, Ca and Sr. Garnet and staurolite porphyryoblasts also exhibit a footprint around mineralisation, extending up to 30 m both above and below the ore zone. High precision thermal ionisation mass spectrometry of zircons extracted from the coherent rhyodacite yield an age of 2759.5 ± 0.9 Ma, which along with geochemical comparisons, places the succession within the 2760–2735 Ma Greensleeves Formation of the Polelle Group of the Murchison Supergroup. Geochemical and geochronological evidence link the coherent rhyodacite sills to the Peter Well Granodiorite pluton ~2 km to the W, which acted as the heat engine driving hydrothermal circulation during VMS mineralisation. This study highlights the importance of both: detailed physical volcanological studies from which an accurate assessment of timing relationships, particularly the possibility of intrusions dismembering ore horizons, can be made; and identifying synvolcanic plutons and other similar suites, for VMS exploration targets in the Youanmi Terrane and worldwide.

The largest Au deposits in the St Ives Goldfield (Yilgarn Craton, Western Australia) may be located in a major Neoarchean volcano-sedimentary depo-centre

The largest Neoarchean gold deposits in the world-class St Ives Goldfield, Western Australia, occur in an area known as the Argo-Junction region (e.g. Junction, Argo and Athena). Why this region is so well endowed with large deposits compared with other parts of the St Ives Goldfield is currently unclear, because gold deposits at St Ives are hosted by a variety of lithologic units and were formed during at least three different deformational events. This paper presents an investigation into the stratigraphic architecture and evolution of the Argo-Junction region to assess its implications for gold metallogenesis. The results show that the region's stratigraphy may be subdivided into five regionally correlatable packages: mafic lavas of the Paringa Basalt; contemporaneously resedimented feldspar-rich pyroclastic debris of the Early Black Flag Group; coarse polymictic volcanic debris of the Late Black Flag Group; thick piles of mafic lavas and sub-volcanic sills of the Athena Basalt and Condenser Dolerite; and the voluminous quartz-rich sedimentary successions of the Early Merougil Group. In the Argo-Junction region, these units have an interpreted maximum thickness of at least 7,130 m, and thus represent an unusually thick accumulation of the Neoarchean volcano-sedimentary successions. It is postulated that major basin-forming structures that were active during deposition and emplacement of the voluminous successions later acted as important conduits during mineralisation. Therefore, a correlation exists between the location of the largest gold deposits in the St Ives Goldfield and the thickest parts of the stratigraphy. Recognition of this association has important implications for camp-scale exploration.

Multiple sulfur isotope analyses support a magmatic model for the volcanogenic massive sulfide deposits of the Teutonic Bore volcanic complex, Yilgarn Craton, Western Australia

We report sensitive high mass resolution ion microprobe, stable isotopes (SHRIMP SI) multiple sulfur isotope analyses (32S, 33S, 34S) to constrain the sources of sulfur in three Archean VMS deposits—Teutonic Bore, Bentley, and Jaguar—from the Teutonic Bore volcanic complex of the Yilgarn Craton, Western Australia, together with sedimentary pyrites from associated black shales and interpillow pyrites. The pyrites from VMS mineralization are dominated by mantle sulfur but include a small amount of slightly negative mass-independent fractionation (MIF) anomalies, whereas sulfur from the pyrites in the sedimentary rocks has pronounced positive MIF, with ∆33S values that lie between 0.19 and 6.20‰ (with one outlier at −1.62‰). The wall rocks to the mineralization include sedimentary rocks that have contributed no detectable positive MIF sulfur to the VMS deposits, which is difficult to reconcile with the leaching model for the formation of these deposits. The sulfur isotope data are best explained by mixing between sulfur derived from a magmatic-hydrothermal fluid and seawater sulfur as represented by the interpillow pyrites. The massive sulfide lens pyrites have a weighted mean ∆33S value of −0.27 ± 0.05‰ (MSWD = 1.6) nearly identical with −0.31 ± 0.08‰ (MSWD = 2.4) for pyrites from the stringer zone, which requires mixing to have occurred below the sea floor. We employed a two-component mixing model to estimate the contribution of seawater sulfur to the total sulfur budget of the two Teutonic Bore volcanic complex VMS deposits. The results are 15 to 18% for both Teutonic Bore and Bentley, much higher than the 3% obtained by Jamieson et al. (2013) for the giant Kidd Creek deposit. Similar calculations, carried out for other Neoarchean VMS deposits give value between 2% and 30%, which are similar to modern hydrothermal VMS deposits. We suggest that multiple sulfur isotope analyses may be used to predict the size of Archean VMS deposits and to provide a vector to ore deposit but further studies are needed to test these suggestions.

Evolution of a ~2.7 Ga large igneous province: A volcanological, geochemical and geochronological study of the Agnew Greenstone Belt, and new regional correlations for the Kalgoorlie Terrane (Yilgarn Craton, Western Australia)

The thick package of ~2.7 Ga mafic and ultramafic lavas and intrusions preserved among the Neoarchean of the Kalgoorlie Terrene in Western Australia provides valuable insight into geological processes controlling the most prodigious episode of growth and preservation of juvenile continental crust in Earth’s history. Limited exposure of these rocks results in uncertainty about their age, physical and chemical characteristics, and stratigraphic relationships. This in turn prevents confident correlation of regional occurrences of mafic and ultramafic successions (both intrusive and extrusive) and hinders the interpretation of tectonic setting and magmatic evolution. A recent stratigraphic drilling program of the Neoarchean stratigraphy of the Agnew Greenstone Belt in Western Australia has provided continuous exposures through a c. 7 km thick sequence of mafic and ultramafic units. In this study, we present a volcanological, lithogeochemical and chronological study of the Agnew Greenstone Belt, and provide the first pre-2690 Ma regional correlation across the Kalgoorlie Terrane. The Agnew Greenstone Belt records ~30 m.y. of episodic ultramafic-mafic magmatism that includes two cycles, each defined by a komatiite that is overlain by units that become more evolved and contaminated with time. The sequence is divided into nine conformable packages, each consisting of stacked subaqueous lava flows and comagmatic intrusions, as well as two sills without associated extrusions. Lavas, with the exception of intercalations between two units, form a layer-cake stratigraphy and were likely erupted from a system of fissures tapping the same magma source. The komatiites are not contaminated by continental crust ([La/Sm]PM ~0.7) and are of the Al-undepleted Munro-type. Crustal contamination is evident in many units (Songvang Basalt, Never Can Tell Basalt, Redeemer Basalt, and Turrett Dolerite), as judged by [La/Sm]>1, negative Nb and Ti anomalies, and geochemical mixing trends towards felsic contaminants. Crystal fractionation was also significant, with early olivine and chromite (Mg#>65) followed by plagioclase and clinopyroxene removal (Mg<65), and in the most evolved case, titanomagnetite accumulation. Three new TIMS dates on granophyric zones of mafic sills and one ICP-MS date from an interflow felsic tuff are presented and used for regional stratigraphic correlation. Cycle I magmatism began at ~2720 Ma and ended ~2705 Ma, whereas cycle II began ~2705 Ma and ended at 2690.7±1.2 Ma. Regional correlations indicate the western Kalgoorlie Terrane consists of a remarkably similar stratigraphy that can be recognised at Agnew, Ora Banda and Coolgardie, whereas the eastern part of the terrane (e.g., Kambalda Domain) does not include cycle I, but correlates well with cycle II. This research supports an autochthonous model of greenstone formation, in which one large igneous province, represented by two complete cycles, is constructed on sialic crust. New stratigraphic correlations for the Kalgoorlie Terrane indicate that many units can be traced over distances >100 km, which has implications for exploration targeting for stratigraphically hosted ultramafic Ni and VMS deposits.

The diverse Grania fauna (Clitellata : Enchytraeidae) of the Esperance area, Western Australia, with descriptions of two new species

Seven species of the marine enchytraeid genus Grania Southern, 1913 are described from sediments sampled during the 2003 International Workshop on the Marine Flora and Fauna of Esperance Bay and the Recherche Archipelago, on the southern coast of Western Australia. Two species are new to science, the euryhaline Tasmanian G. dolichura Rota and Erseus, 2000 represents a new record for the state, and the remaining four species were known from other parts of Western Australia. Grania quaerens sp. n. is recognized by having a high chaetal index (= 5 short chaetal foot), small coelomocytes, penial apparati with long whip-like terminal stylets, conspicuous spermathecae with ectally bulbous ducts, and ectally granulated ampullae housing sperm rings in their ental region. Grania sperantia sp. n. is readily distinguishable by the complete lack of lateral chaetae, a multiple-banded pattern of the clitellum, extremely long sperm funnels, and the intrasegmental location of the spermathecal pores. The latter new species and four others in the collection (G. bykane Coates, 1990, G. crassiducta Coates, 1990, G. dolichura, and G. ersei Coates, 1990) are remarkable in possessing the head organ, a sensory structure unique to Grania that was not noted previously in Western Australian species. When considering the whole genus, the geographic pattern of the head organ appears southern-centred: of the 17 species of Grania reported to possess it, as many as 13 inhabit the southern latitudes. The seventh species of the Esperance collection, G. vacivasa Coates and Stacey, 1993, is notable for the kind of items found in its gut and the unusual appearance of its pygidium.

Environmental Aspects of Underground Construction and Exploration of Underground Structure – State of the Art

An underground work (such as a tunnel or a cavern) has many, well known, environmental qualities such as: no physical barriers crossing the land, less maintenance costs than an analogous surface structure, less expenses for heating and conditioning; a localized emission of noise, gas, dust during operation and, finally, a better protection against seismic actions.
It cannot be forgotten, anyway, that some negative environmental features are present such as, for example, : perturbation, pollution and drainage of the groundwater; settlements; disposal of waste rock.
In the paper the above mentioned concepts are discussed and analysed to give a global overview of all this aspects.

The development of soil organic matter in restored biodiverse Jarrah forests of South-Western Australia as determined by ASE and GCMS

Background, aim and scope Soil organic matter (SOM) is known to increase with time as landscapes recover after a major disturbance; however, little is known about the evolution of the chemistry of SOM in reconstructed ecosystems. In this study, we assessed the development of SOM chemistry in a chronosequence (space for time substitution) of restored Jarrah forest sites in Western Australia. Materials and methods Replicated samples were taken at the surface of the mineral soil as well as deeper in the profile at sites of 1, 3, 6, 9, 12, and 17 years of age. A molecular approach was developed to distinguish and quantify numerous individual compounds in SOM. This used accelerated solvent extraction in conjunction with gas chromatography mass spectrometry. A novel multivariate statistical approach was used to assess changes in accelerated solvent extraction (ASE)-gas chromatography-mass spectrometry (GCMS) spectra. This enabled us to track SOM developmental trajectories with restoration time. Results Results showed total carbon concentrations approached that of native forests soils by 17 years of restoration. Using the relate protocol in PRIMER, we demonstrated an overall linear relationship with site age at both depths, indicating that changes in SOM chemistry were occurring. Conclusions The surface soils were seen to approach native molecular compositions while the deeper soil retained a more stable chemical signature, suggesting litter from the developing diverse plant community has altered SOM near the surface. Our new approach for assessing SOM development, combining ASE-GCMS with illuminating multivariate statistical analysis, holds great promise to more fully develop ASE for the characterisation of SOM.

Seedling response to phosphate addition and inoculation with arbuscular mycorrhizas and the implications for old-field restoration in Western Australia

We predicted that P-fertiliser residues will limit the establishment of native plant species and their mycorrhizas to old-fields in the wheat-growing region (i.e. the wheatbelt) of Western Australia. To test this prediction, we assessed the growth and P uptake of seedlings of three native plant species to phosphate addition and inoculation with arbuscular mycorrhizas (AM) in a pot study. The native plant species were Acacia acuminata Benth. (Mimosaceae), Eucalyptus loxophleba Benth. subsp. loxophleba (Myrtaceae) and Hakea preissii Meisn. (Proteaceae); and each pot contained one seedling. P was added to field soil to mimic pre-agricultural (P0), old-field (P1) and 10 times old-field (P10) soils. AM inoculant, which was a mix of Scutellospora calospora (Nicolson and Gerdemann) Walker and Sanders, Glomus intraradices Schenck and Smith and Glomus mosseae (Nicolson and Gerdemann) Gerdemann and Trappe, was added to half of the pots. After 12 weeks, the biomass and P uptake of the mycorrhizal A. acuminata were greater than those of the non-mycorrhizal plants across all P treatments. Plant biomass decreased significantly with increasing P addition, yet this species was apparently unable to suppress its mycorrhizal colonisation at high P despite this reduction in growth. In contrast, mycorrhizal and non-mycorrhizal E. loxophleba subsp. loxophleba were of a similar biomass after 12 weeks; maximum biomass was attained at intermediate (old-field) levels of P. P uptake increased with increasing P supply, beyond that required to attain maximum biomass. AM did not form on H. preissii. P uptake increased with increasing P supply for this species also. Overall, it is the apparent inability of these species to down-regulate P uptake rather than a lack of mycorrhizal symbiosis that will constrain their establishment on wheatbelt old-fields.

Unique marine Permian-Triassic boundary section from Western Australia

A unique marine Permian-Triassic boundary section containing rich oil source rocks has been continuously cored in a petroleum borehole from the Perth Basin of Western Australia. Such sequences, which provide a biostratigraphic and environmental record at the time of the largest extinction event of the past 500 million years, are globally rare, and this is the first to be documented in Australia. Throughout geological history there have been periods of global marine anoxia that commonly resulted in the widespread deposition of petroleum source rocks, most notably in the mid-Cretaceous and Late Jurassic. An apparent paradox is that, previously, source rocks have not been recognised in association with the Permian-Triassic boundary, despite widespread marine anoxia at this time. The Perth Basin source rocks contain abundant and unusual biomarkers, apparently related to the highly specialised and limited biota that flourished in the aftermath of the end-Permian extinction event. Local conditions may have favoured source-rock development, either due to higher productivity resulting from coastal upwelling or through enhanced preservation under strongly anoxic conditions.

Living with Dungalah (Murray River) : the case study of an environmental issue in Australia

This research is a case study of Dungalah, a river Europeans call the Murray which describes and accounts for the past, present and future experiences of Indigenous and non-Indigenous communities in their protection, use and management of the Dungalah and its surrounding land. It provides a snapshot of the experiences of the researcher, her family, friencds and the Yorta Yorta people, living with Dungalah.

Invasive species can't cover their tracks : using microsatellites to assist management of starling (Sturnus vulgaris) populations in Western Australia

Invasive species are known to cause environmental and economic damage, requiring management by control agencies worldwide. These species often become well established in new environments long before their detection, resulting in a lack of knowledge regarding their history and dynamics. When new invasions are discovered, information regarding the source and pathway of the invasion, and the degree of connectivity with other populations can greatly benefit management strategies. Here we use invasive common starling (Sturnus vulgaris) populations from Australia to demonstrate that genetic techniques can provide this information to aid management, even when applied to highly vagile species over continental scales. Analysis of data from 11 microsatellites in 662 individuals sampled at 17 localities across their introduced range in Australia revealed four populations. One population consisted of all sampling sites from the expansion front in Western Australia, where control efforts are focused. Despite evidence of genetic exchange over both contemporary and historical timescales, gene flow is low between this population and all three more easterly populations. This suggests that localized control of starlings on the expansion front may be an achievable goal and the long-standing practice of targeting select proximal eastern source populations may be ineffective on its own. However, even with low levels of gene flow, successful control of starlings on the expansion front will require vigilance, and genetic monitoring of this population can provide essential information to managers. The techniques used here are broadly applicable to invasive populations worldwide.

Early Triassic (early Olenekian) life in the interior of East Gondwana: Mixed marine-terrestrial biota from the Kockatea Shale, Western Australia

A new terrestrial-marine assemblage from the lower beds of a thin outcrop section of the Kockatea Shale in the northern Perth Basin, Western Australia, contains a range of fossil groups, most of which are rare or poorly known from the Lower Triassic of the region. To date, the collection includes spinose acritarchs, organic-cemented agglutinated foraminifera, lingulids, minute bivalves and gastropods, ammonoids, spinicaudatans, insects, austriocaridid crustaceans, actinopterygians, a temnospondyl-like mandible, plant remains, and spores and pollen. Of these groups, the insects, crustaceans and macroplant remains are recorded for the first time from this unit. Palynomorphs permit correlation to nearby sections where conodonts indicate an early Olenekian (Smithian) age. The locality likely represents the margin of an Early Triassic shallow interior sea with variable estuarine-like water conditions, at the southwestern end of an elongate embayment within the East Gondwana interior rift-sag system preserved along the Western Australian margin. Monospecific spinose acritarch assemblages intertwined with amorphous organic matter may represent phytoplankton blooms that accumulated as mats, and suggest potentially eutrophic surface waters. The assemblage represents a mixure of marine and terrestrial taxa, suggesting variations in water conditions or that fresh/brackish-water and terrestrial organisms were transported from adjacent biotopes. Some of the lower dark shaly beds are dominated by spinicaudatans, likely indicating periods when the depositional water body was ephemeral, isolated, or subjected to other difficult environmental conditions. The biota of the Kockatea Shale is insufficiently known to estimate biotic diversity and relationships of individual taxa to their Permian progenitors and Triassic successors, but provides a glimpse into a coastal-zone from the interior of eastern Gondwana. Specialist collecting is needed to clarify the taxonomy of many groups, and comparisons to other Lower Triassic sites are required to provide insights into the pattern of biotic decline and recovery at the end-Permian crisis.

Development by design in Western Australia : Overcoming offset obstacles

Biodiversity offsets can be an important tool for maintaining or enhancingenvironmental values in situations where development is sought despite negativeenvironmental impacts. There are now approximately 45 compensatory mitigationprograms for biodiversity impacts worldwide, with another 27 programs in development. While offsets have great potential as a conservation tool, their establishment requires overcoming a number of conceptual and methodological hurdles. In Australia, new policy changes at the national and state (i.e., Western Australia) level require that offsets follow a set of general principles: (1) Environmental offsets may not be appropriate for all projects and will only be considered after avoidance and mitigation options have been pursued;(2) Environmental offsets will be based on sound environmental information andknowledge; (3) Establishing goals for offsets requires an estimate of expected direct and indirect impacts; (4) Environmental offsets will be focused on longer term strategic outcomes; (5) Environmental offsets will be cost-effective, as well as relevant and proportionate to the significance of the environmental value being impacted. Here we focus on the challenges of determining and implementing offsets using a real world example from a voluntary offset process undertaken for Barrick Gold’s Kanowna Belle mine site in Western Australia to highlight those challenges and potential solutions.