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Substantial new information is presented on upper Artinskian–Kungurian deposits in Timor-Leste and in the Canning, Southern Carnarvon and northern Perth basins of Western Australia. These basins, situated between about 35°S and 55°S palaeolatitude, formed part of the East Gondwana interior rift, a precursor to the rift that 100 my later formed the Indian Ocean in this region. Timor lay near the main axis of the East Gondwana interior rift, whereas the Western Australian basins were marginal splays from the rift axis. The main depocentres developed as a result of faulting that was initiated during the Late Pennsylvanian. Detailed lithostratigraphic and biostratigraphic analyses have been made on the newly recognized Bua-bai limestone and the type Cribas Group in Timor, the Noonkanbah Formation in the Canning Basin, the Byro Group in the Merlinleigh Sub-basin of the Southern Carnarvon Basin, and the Carynginia Formation in the northern Perth Basin. In Timor the succession, which is highly disrupted by faulting, was deposited under open-marine conditions probably in a shelf–basin setting. Restricted, very shallow-water seas flooded the Canning Basin and the Merlinleigh–Byro–Irwin sub-basins of the Southern Carnarvon and northern Perth basins and had highly variable oxygen levels and salinities typical of estuarine environments. A similar pattern of warming and bathymetric change is recognized in all studied basins. During the early part of the late Artinskian cool conditions prevailed, with water temperatures 0–4 °C forming sea ice in the Merlinleigh–Byro–Irwin rift. Rapid warming during the latter part of the late Artinskian was accompanied by maximum marine flooding close to the Artinskian–Kungurian boundary. Climatic and bathymetric conditions then allowed carbonate mounds, with larger fusulines and a variety of algae, to develop in the northern part of the rift system, and Tubiphytes , conodonts, and brachiopods with Tethyan affinities to migrate into the marginal-rift basins despite the generally adverse water quality at these depositional sites. Comparison between the stratigraphic record from the East Gondwana interior rift and coeval records from Lhasa and Sibumasu indicate a similar pattern of climate change during the Carboniferous to end Cisuralian. Similar trends probably are present in Eastern Australia although there is confusion over the correlation of some units. [ABSTRACT FROM AUTHOR]

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. [ABSTRACT FROM AUTHOR]

Shallow-marine methane seeps, described here for the first time from the Australian Upper Paleozoic, are among few reported globally from the Carboniferous–Permian. Carbonate-cement fabrics, δ13C values and biota indicate that concentrations of nodules scattered in a narrow stratigraphic interval within the lower Holmwood Shale in the Irwin Basin formed in methane seeps. Based on ammonoids, this zone belongs within the Sakmarian. The Holmwood Shale overlies the glaciogenic Nangetty Formation that sits on crystalline Precambrian basement. The Holmwood is little deformed, shows low thermal maturation and has been covered by less than 1000 m of Permian and Neogene strata. The nodules are cementstone with complex multiphase cement fabric and δ13C values (mostly, ‐25 – -45‰ VPDB) below the ranges for normal-marine limestone and carbonate nodules common in marine shale elsewhere. A biota preserved in nodules of the seep deposits includes representatives of three ecosystems: seep, pelagic, and coastal plain. The seep biota, new to the Australian Permian, consists of small thickets with a framework of tubeworms, less common algal-like Tubiphytes , and problematica (? algae or sponges). Other components include microbial mats, macrophyte alga Litostroma (first report from Gondwana); foraminifers; sponges with siliceous monaxon spicules; a new group of small, lightly ornamented rostroconchs; microgastropods and rare larger types; ostracods and minute scolecodonts from polychaete jaws. Elements of the pelagic ecosystem are ammonoids (abundant in enclosing shale) and marine microphytoplankton. Probable vertebrate bone (possibly amphibians) and diverse spores and pollen from land plants come from the adjoining coastal plain. The surrounding mudstone lacks benthic macrofauna but includes an unusual assemblage of siliceous agglutinated foraminifers. The seeps were oases of high organic productivity on an otherwise barren muddy seafloor. The Holmwood Shale's seep carbonates have close similarities to modern seep deposits in shallow-marine settings. They more closely resemble the modern deposits than some of the few others interpreted elsewhere from the Carboniferous–Permian, but seem close to equivalents in shale of latest Pennsylvanian (Gzhelian) age overlying glaciogenic deposits in the Namibian sector of East Gondwana. In both regions, deglaciation of Pennsylvanian ice sheets that covered large parts of East Gondwana, dewatering of melt-water from the glaciogenic sediment pile after burial, and associated release of probable biogenic methane seems to have coincided with formation of seeps. • First reported methane seeps in Australian Upper Paleozoic. • Among few Permian methane-seep occurrences recognized globally. • Concentrations of carbonate nodules in thick marine mudstone above glaciogenic unit. • Post-glacial shallow marine conditions in interior sea with flat seafloor. • Nodules with cement fabrics, biota, and δ13C values similar to those in modern seeps. [ABSTRACT FROM AUTHOR]

Foraminifera are documented from the type section of the Quinnanie Shale in order to interpret their bathymetric distributions in a shallow high-latitude interior sea during the Kungurian. The marine setting was a narrow elongate half-graben (Merlinleigh Sub-Basin of the Southern Carnarvon Basin) in the Western Australian portion of eastern Gondwana. The Quinnanie Shale is part of the Byro Group of formations that display pronounced shale–sand cyclicity recording frequent changes in bathymetry. The type section of the Quinnanie Shale shows an overall progradational pattern in lithofacies, and consists of five ‘cycles’, each culminating in a prominent sandstone bed. Foraminifera are abundant in the shale and are almost entirely siliceous (organic-cemented) agglutinated types that probably dominated the original fauna of the interior sea. Hierarchical cluster analysis of samples taken every meter through the 162-m-thick type section is used to distinguish ten biofacies, each defined by a different set of dominant agglutinated species. Although biofacies frequently change up-section, there is an overall trend that is related to the progradational trend suggested by the lithofacies. Based on comparisons between lithofacies and biofacies, a palaeobathymetric zonation is established for the foraminifera. This zonation, the sparse macrofauna, and the lithofacies suggest that the interior sea was stratified in terms of salinity and dissolved oxygen levels, and the water was generally hyposaline. Most of the agglutinated foraminiferal species have analogous morphotypes present in modern confined estuaries and interior seas and this points to great conservatism in the evolutionary and ecological development of this component of interior-sea faunas. Aaptotoichus quinnaniensis sp. nov., an organic-cemented agglutinated foraminifer, is described from the Quinnanie Shale type section. [Copyright &y& Elsevier]

The Trealla Limestone, which forms a veneer of foraminiferal-rich limestone and covers over 4000 km2 of the tectonically stable Southern Carnarvon Platform, contains the oldest evidence for seagrass meadows known in Western Australia. It belongs to Lower Tf1 Letter Stage (based on larger benthic foraminifers) of the Burdigalian, within interval 19–16 Ma, and is the only Miocene unit on the platform. The Trealla Limestone here is coeval to the deeper water lower part of the much thicker Trealla Limestone in the Exmouth Sub-basin to the northwest. A seagrass-meadow depositional environment is indicated by most of the studied microfacies based on comparisons with modern sediment composition and foraminiferal assemblages found in innermost shelf seagrass banks between 23°S and 32°S on the present Western Australian coast. Some levels in the Trealla Limestone on the platform (e.g. with abundant miliolid foraminifers, and absence of coral debris) probably were deposited in and around dense seagrass meadows similar to those present today in the metahaline (40–55 ppt salinity) reaches of Shark Bay; whereas other levels (e.g. coral floatstone) were deposited under normal-marine conditions. Based on comparisons with modern carbonate sediment and biota in the region, the biogenic composition of the Trealla Limestone on the platform suggests winter minimum sea-surface temperatures within the range of 17–22 °C. The Nullabor Limestone in the Eucla Basin, at 10° further south on the southern Australian margin, is similar, at least in part, in composition and age to the Trealla Limestone on the Southern Carnarvon Platform. Both may have been deposited during a Burdigalian sea-level rise, and during part of the Miocene climate optimum recognized elsewhere. Sediment composition and foraminiferal assemblages (including epiphytic types) found in the Trealla and Nullabor limestones are similar to those in the modern seagrass banks of the region. This suggests that seagrasses similar to the extensive Posidonia and Amphibolus stands, which are dominant today between 25°S and 35°S along the Western Australian coast, were widespread during the Burdigalian. • Only Miocene unit on the Southern Carnarvon Platform is thin Trealla Limestone. • Larger benthic foraminifera indicate Burdigalian (19–16 Ma) age. • Seagrass meadow deposition indicated by modern sediment and foraminiferal analogues. • Meadows lived under normal-marine and metahaline salinities as on present coast. • Miocene meadows were similar to present-day Posidonia–Amphibolus stands. [ABSTRACT FROM AUTHOR]

Sulfate-driven anaerobic oxidation of methane (SD-AOM) is the key biogeochemical process at marine seeps, seafloor environments sustaining lush chemosynthesis-based life. While an extensive molecular record of SD-AOM has been established for Cenozoic and Mesozoic seeps, to date only one reported case of SD-AOM exists for the Paleozoic. To get new insight into the dominant biogeochemical processes at Paleozoic seeps, a detailed lipid biomarker study was conducted on post-glacial early Permian seep carbonates from Western Australia. The encountered biomarker inventory comprises two diagnostic isoprenoid hydrocarbons with low δ13C values: mixed phytane and crocetane (−124 to −110‰) and 2,6,10,15,19-pentamethylicosane (PMI; −128 to −102‰), compounds known to be produced by anaerobic methane-oxidizing archaea (ANME). Other known biomarkers of ANME like glycerol dibiphytanyl glycerol tetraethers (GDGTs) and sn 2-hydroxyarchaeol are not preserved in the Permian seep deposits despite the low to moderate thermal maturity of the Paleozoic limestones. Still, degradation products of these compounds including biphytanes and phytane, respectively, yield δ13C values (biphytanes: −117 to −111‰) typical of ANME lipids. The combined phytane/crocetane peaks show similar 13C depletion as other ANME lipids, suggesting a derivation of the precursor lipids of phytane from ANME. Among the detected lipids, biomarkers of sulfate-reducing bacteria, the syntrophic partners of ANME in SD-AOM, include the 13C-depleted terminally branched fatty acids iso- and anteiso- C 15:0 and -C 17:0 as well as iso - and anteiso -alkanes with 15 and 17 carbons (δ13C values: −97 to −63‰), the latter representing probable degradation products of fatty acid and bacterial mono- and diether precursors. ANME-derived lipids (phytane and PMI) are recognized as organic sulfur compounds (OSCs) in the free hydrocarbon fraction, comprising thiolanes, thianes, and thiophenes. The ANME-derived OSCs are accompanied by sulfurized alkanes with 16 and 18 carbons (δ13C values: −83 to −79‰), tentatively interpreted to derive from unsaturated glycerol ester or ether lipids synthesized by seep-dwelling sulfate-reducing bacteria, while a derivation of these compounds from sulfide-oxidizing bacteria can neither be substantiated nor excluded. We suggest that OSCs formed in the shallow sedimentary subsurface during early diagenesis, reflecting fast entombment and preservation in authigenic carbonates. Rapid OSC formation was probably caused by (1) the presence of excess hydrogen sulfide, which derived from SD-AOM and (2) the scarcity of reactive iron. The studied Permian seep limestones of Western Australia expand our knowledge of the biogeochemical processes at Paleozoic seeps and provide a unique example of how early sulfurization of organic compounds may aid the preservation of biomarkers. • 13C-depleted biomarkers of SD-AOM consortia are found in Permian seep carbonates. • Excess hydrogen sulfide from SD-AOM may have induced the formation of organic sulfur compounds (OSCs). • Bacterial OSCs correspond to lipids synthesized by SD-AOM consortia. • OSCs represent the products of early diagenesis in shallow post-glacial sediments. [ABSTRACT FROM AUTHOR]

Growth variability in extant Peneroplis has drawn attention since early times. There is general agreement that the aberrations in recent populations of Peneroplis are natural and intraspecific. For these reasons, some authors have questioned the systematic relationships among living Peneroplis species. In this study, we explore variation in an exceptionally abundant population of Peneroplis from Pete's Pond, a permanent wetland, within the Lake Macleod Evaporate Basin, Western Australia. The area is unusual because foraminifera are isolated from the nearby ocean, except for a 15-km subterranean karst system that permits a constant delivery of seawater. Pete's Pond water salinities are either less than or at normal seawater levels. The morphological variations identified have been grouped, with morphogroups A, B, and C referred to as variants of the Peneroplis growth pattern, including morphotypes with high flaring and cylindrical uniserial chambers. Morphogroups D and E are referred to as 'abnormal' aberrant forms, which show bifurcated serial chambers or a disordered growing style. Variants are the most critical in terms of taxonomic discrimination. Here we recommend the following morphological constraints for species determination of Peneroplis variants: i) degree of involution of early chambers; ii) presence/absence of umbilical depressions, iii) incision of sutures and iv) ornament, including the presence and disposition of small pits or ribs. Aberration in Peneroplis is considered to be linked to strict environmental parameters that have led to optimum shell growth as well as to having a key role in the phylogenesis of Soritoidea through deep time. • Pete's Pond environment is characterized by mangrove and marine nektonic and benthonic species. • Peneroplis aberrations occur in a time span of at least 32 years and are linked to the environmental parameters. • Pete's Pond could become a model to explain morphological abnormalities in recent and fossil benthic foraminifera. • The population is a reservoir of phenotypic diversity useful to explain the radiations of soritids through deep time. [ABSTRACT FROM AUTHOR]