Fossil crayfish are typically rare, worldwide. In Australia, the strictly Southern Hemisphere clade Parastacidae, while ubiquitous in modern freshwater systems, is known only from sparse fossil occurrences from the Aptian–Albian of Victoria. We expand this record to the Cenomanian of northern New South Wales, where opalized bio-gastroliths (temporary calcium storage bodies found in the foregut of pre-moult crayfish) form a significant proportion of the fauna of the Griman Creek Formation. Crayfish bio-gastroliths are exceedingly rare in the fossil record but here form a remarkable supplementary record for crayfish, whose body and trace fossils are otherwise unknown from the Griman Creek Formation. The new specimens indicate that parastacid crayfish were widespread in eastern Australia by middle Cretaceous time, occupying a variety of freshwater ecosystems from the Australian–Antarctic rift valley in the south, to the near-coastal floodplains surrounding the epeiric Eromanga Sea further to the north.

The age of granophyric diorite from the Sosnowiec IG-1 borehole (Brunovistulia Terrane) was studied by means of U–Pb single-grain zircon analysis performed on a SHRIMP (sensitive high-resolution ion microprobe) IIe device. The isotope ages and provenance of zircons from the Emsian tuffs cropping out in the southern part of the Holy Cross Mountains (Małopolska Terrane) were also investigated using the same method. The age of the diorite intrusion (420 ± 2 Ma) is comparable with the combined Ar–Ar/magnetostratigraphic age of the Bardo diabase intrusion from the northern part of the Małopolska Terrane. These intrusions were emplaced during the same event of regional tectonic extension associated with the Rheic Ocean closure and the onset of processes creating the Rheno-Hecynian Basin near the Silurian/Devonian boundary. A negative Nb anomaly characteristic of both intrusions could be linked with the subduction of the Rheic oceanic crust under the SE margin of the Old Red Continent. Emsian magmatic activity in the distant Rheno-Hercynian Zone provided several tuff layers in the northern part of the Małopolska Terrane. As can be inferred from zircon ages, these tuffs were derived from mafic eruptions that cut sedimentary rocks containing detrital zircons transported from Baltica. This interpretation fits the existing models of development of the Rheno-Hercynian Basin in the Emsian.

Bennett Island stands alone in a remote part of the Arctic and information on its geology is essential to ascertain relations with other terranes in order to restore the early Palaeozoic Arctic palaeogeography. Lower Palaeozoic sedimentary rocks throughout the island were studied thoroughly for the first time. The Ordovician section (> 1.1 km thick) comprises three units: Tremadocian, lowest Floian black shale (130–140 m); Floian, lower Dapingian carbonate turbidite (> 250 m); and Dapingian, lower Darriwilian siliciclastic turbidite (> 730 m). Ordovician deposits conformably overlie Cambrian rocks deposited within the Siberian shelf, as shown earlier. Most of the Ordovician succession was formed in a deep trough that received carbonate debris from a nearby carbonate platform and silicate material from a distant landmass located to the NE (present coordinates). The Bennett Island Ordovician rocks have much in common with those of both the Central and Northern Taimyr belts. It could be tentatively suggested that both belts merged at their eastern continuation in the vicinity of De Long Islands. The whole system probably extends further eastwards. The Ordovician facies patterns and faunal assemblages in the New Siberian Islands are notably similar to those of northwestern Alaska, where the same lateral transition from turbidites to shelf limestones was reported.

The carbon isotope value of ethane in the southern part of the Jingbian gas field is lower than that in the northern part, indicating a carbon isotopic reversal in the southern Jingbian gas field (δ13Cmethane > δ13Cethane). Through comparing the geochemical characteristics of gases in the southern and northern parts of the gas field, the reasons for the carbon isotopic reversal in the southern Jingbian gas field were determined to be high thermal maturity and mixing action. When thermal maturity reaches a critical value, the carbon isotope value of ethane becomes relatively more depleted with thermal maturity. Although the carbon isotope value of methane increases with thermal maturity, the extent is relatively smaller. Finally, the rare phenomenon of δ13Cmethane > δ13Cethane occurs. High thermal maturity leads to the secondary thermal cracking of gases. Mixing of the cracked gases and primary gases also leads to carbon isotopic reversal. Both of the above mechanisms share a common premise, which is high thermal maturity.

The Gangdese magmatic belt across the southern Tibetan Plateau is juxtaposed with the Indus–Yurlung Zangbo suture zone (IYS), and many mafic microgranular enclaves (MMEs) are exposed in the belt, thus providing a window for observing deep crust–mantle processes related to the Indo-Asian collision. The Nyemo intrusion is located in the middle part of the Gangdese magmatic belt and comprises host diorites with abundant MMEs. Compared with other parts of the Gangdese magmatic belt, the host rock of the Nyemo intrusion has a mineral composition similar to that of the MME, although differences are observed in chemical contents. To explore the genetic type of the MMEs and the deep processes of the Gangdese magmatic belt, the Nyemo intrusion is selected as the research object for this paper. Here, we report zircon U–Pb geochronological and whole-rock geochemical data for host diorites and MMEs, and electron probe data for hornblendes in diorites and MMEs, and combine mineralogy, petrology, petrogeochemistry and isotope geochemistry analyses. Research has shown that diorites in the Nyemo intrusion belong to the medium-K, metaluminous series. The light rare earth elements (LREEs) and heavy rare earth elements (HREEs) are significantly fractionated, and the LREE/HREE values are 5.77–7.71. The (87Sr/86Sr)i values of the diorites range from 0.704260 to 0.704287, and the εNd(t) values are from 3.73 to 4.17. The MMEs in the Nyemo intrusion have a limited range of SiO2 contents, are calc-alkaline with metaluminous affinity, and have relatively high contents of MgO (4.34–5.00 wt %) with Mg# (Mg2+/Mg2+ + Fe2+) values of 42.36–43.53, which is close to that of evolved basic magma. The contents of REEs vary from 108.87 to 120.59 ppm and show obvious Eu anomalies. The (87Sr/86Sr)i values of the MMEs range from 0.704680 to 0.704704, and the εNd(t) values are 0.35–3.74. The crystallization temperature of the hornblende in the diorite is 820 °C, the formation depth is 5.39 km, the oxygen fugacity is ΔNNO + 0.88 and the water content is 5.95 %. The crystallization temperature of the hornblende in the MMEs is 880 °C, the formation depth is 12.18 km, the oxygen fugacity is ΔNNO + 0.38 and the water content is 8.27 %. The Nyemo MMEs are formed by magma mingling, and originate from the partial melting of the depleted mantle, while the host diorite originates from partial melting of the juvenile crust with the addition of mantle material. The formation of the Gangdese magmatic belt is related to the Indo-Asian continental collision. The break-off of the subducted Neo-Tethyan oceanic plate triggered partial melting of the asthenosphere, which resulted in accumulation of the basaltic magma and then caused the partial melting of the juvenile crust with the addition of mantle material, thus forming a variety of granitic rocks and the large Gangdese magmatic belt.

Dinoflagellate cyst assemblages recovered from the La Meseta Formation cropping out in Seymour Island, Antarctic Peninsula, are studied herein and their distribution is compared with the biostratigraphic scheme available for the Palaeogene of the Southern Ocean and other high-latitude regions. In this way, the La Meseta Formation is dated as middle Lutetian to Priabonian (46.2–36 Ma), which differs from the age provided by other fossils, isotopes and also with the magnetostratigraphic scheme recently performed for the unit. The dinoflagellate cyst data support the proposal of ocean circulation patterns on the South American Shelf prior to the opening of Drake Passage. Assemblages from the La Meseta Formation contain Antarctic-endemic taxa which are also dominant in several circum-Antarctic sites, located south of 45° S. Their distribution reflects an ocean-circulation scheme with wide clockwise gyres surrounding Antarctica that were disrupted as a consequence of the deepening and definitive apertures of the Tasmanian Gateway and Drake Passage towards the Eocene/Oligocene transition. The palaeoenvironmental inference based on the S/D ratio (sporomorphs versus dinoflagellate cysts) and the P/G ratio (peridinioid versus gonyaulacoid dinoflagellate cysts) suggests an overall trend through the section from marine-dominated assemblages with poorly productive waters in the lower part of the section to more terrestrially dominated assemblages with increasing productivity in the upper part of the unit, reflecting a shallowing trend to the top.

The establishment of permanent animal communities on land was a defining event in the history of evolution, and one for which the ichnofauna and facies of the Tumblagooda Sandstone of Western Australia have been considered an archetypal case study. However, terrestrialization can only be understood from the rock record with conclusive sedimentological evidence for non-marine deposition, and original fieldwork on the formation shows that a marine influence was pervasive throughout all trace fossil-bearing strata. Four distinct facies associations are described, deposited in fluvial, tidal and estuarine settings. Here we explain the controversies surrounding the age and depositional environment of the Tumblagooda Sandstone, many of which have arisen due to the challenges in distinguishing marine from non-marine depositional settings in lower Palaeozoic successions. We clarify the terminological inconsistency that has hindered such determination, and demonstrate how palaeoenvironmental explanations can be expanded out from unambiguously indicative sedimentary structures. The Tumblagooda Sandstone provides a unique insight into an early Palaeozoic ichnofauna that was strongly partitioned by patchy resource distribution in a littoral setting. The influence of outcrop style and quality is accounted for to contextualize this ichnofauna, revealing six distinct low-disparity groups of trace fossil associations, each related to a different sub-environment within the high-ichnodisparity broad depositional setting. The formation is compared with contemporaneous ichnofaunas to examine its continued significance to understanding the terrestrialization process. Despite not recording permanent non-marine communities, the Tumblagooda Sandstone provides a detailed picture of the realm left behind by the first invertebrate pioneers of terrestrialization.

Production, transport and deposition of aeolian dust from land to sea closely interact with regional environment and global climate. This Special Issue addresses transport of aeolian dust from the Asian inland to the Loess Plateau and North Pacific Ocean and their possible links to oceanic ecosystem, global climate and even human activity, over various timescales. The papers in this volume are multidisciplinary in nature and include sedimentology, mineralogy, geochemistry, environmental magnetism and climate modelling on multi-timescales from interannual, glacial–interglacial to tectonic timescales. Based on modern observation, geological records and modelling, this Special Issue offers new insights especially into aeolian provenance, dynamics controls on dust production, a novel marine aeolian proxy, as well as long-term aeolian input to the marginal basins of NE Asia and its influence on oceanic productivity. This issue provides a good example for future comprehensive studies of source-to-sink processes of Asian dust from land to sea.

High-pressure low-temperature metamorphic sediments of the Phyllite–Quartzite unit sensu stricto and the Talea Ori group are investigated in the field, microstructurally and by U–Pb dating of detrital zircons to shed light on their palaeogeographic origin. Zircon age spectra with ages >450 Ma of the Phyllite–Quartzite unit sensu stricto indicate a palaeogeographic origin at the northern margin of East Gondwana. In contrast, the lower stratigraphic, siliciclastic formations of the Talea Ori group show a high number of well-rounded Cambrian to Early Carboniferous aged zircons and a Neoproterozoic zircon age spectrum with East Gondwana affinity. Based on the comparison of zircon age data, a possible distal sediment source is the Sakarya Zone at the southern active margin of Eurasia. To reconcile the zircon data with the geological observations we propose different alternative models, or a combination of these, including sediment transport from the Sakarya Zone and/or a westerly source towards the northern margin of Gondwana as well as terrane-displacement of the Sakarya Zone. Also, a palaeogeographic origin of the Talea Ori group at the southern active margin of Eurasia cannot be excluded. This alternative, however, would not be consistent with the usually assumed association of the Talea Ori group with the Plattenkalk unit characterized by a palaeogeographic origin at the northern margin of Gondwana.

This paper presents three different age domains, obtained by electron microprobe monazite dating, for granulitic gneisses collected from the Shillong-Meghalaya Gneissic Complex in Sonapahar, NE India, which contain radioactive materials, e.g. thorium (3.32–7.20 wt %), uranium (0.133–1.172 wt %) and lead (0.101–0.513 wt %). The microprobe analyses of monazite grains in the rock samples show that the monazites have three different ages ranging from Mesoproterozoic to Neoproterozoic. The oldest age (1571 ± 22 Ma) represents a peak metamorphic event, the youngest dominant age indicates the Pan-African tectonic event (478 ± 7 Ma) and the intermediate age marks the Grenvillian orogeny (1034 ± 91 Ma) or may be a mixing artefact; these ages are located at the cores, rims and intermediate parts of the monazite grains, respectively. The equilibrium mineral phases calculated for the granulitic gneisses from Sonapahar lie in a P–T range from 5.9 kbar/754 °C to 8.3 kbar/829 °C in the NCKFMASH system. Plotting the P–T conditions of the granulitic gneisses reveals a clockwise P–T path. Two major metamorphic events are observed in Sonapahar. The M1 metamorphic stage is represented by peak mineral assemblages of prograde garnet-forming reactions (8.2 kbar/∼713 °C) during Mesoproterozoic time (1571 ± 22 Ma). The M2 metamorphic stage featured decompression (3.9 kbar/∼701 °C) in which garnet–sillimanite broke down to form cordierite along an isothermal decompression path during the Pan-African tectonic event (478 ± 7 Ma).

Smithian–lower Anisian strata in Peary Land, North Greenland, were deposited at ∼45° N on the northern margin of Pangaea in offshore to upper shoreface settings. The well-constrained succession (palynology and ammonite biostratigraphy) documents a remarkable shift from lycophyte spore-dominated assemblages in the upper Smithian to gymnosperm pollen-dominated ones in the lower Spathian in concert with a marked shift of +6 ‰ in δ13Corg. Correlation with other Smithian–Spathian boundary sections that record terrestrial floral changes indicates that the recovery of gymnosperms began earlier in the mid-latitudes of the Southern Hemisphere than in the Northern Hemisphere. The lycophyte-dominated Late Smithian Thermal Maximum is here interpreted as reflecting dry and hot climatic conditions with only brief seasonal precipitation unable to sustain large areas of gymnosperm trees, but able to revive dehydrated lycophytes. This suggests that the Late Smithian Thermal Maximum was a time of widespread aridity, which is also supported by red bed deposition in many areas globally, even as far south as Antarctica. The shift to gymnosperm-dominated vegetation during the cooling across the Smithian–Spathian boundary reflects a change to seasonally more humid climatic conditions favouring gymnosperm recovery, and could have been initiated by increased albedo over land due to the widespread aridity during the Late Smithian Thermal Maximum. The recovery of gymnosperm vegetation would have helped to draw down CO2 from the atmosphere and exacerbate global cooling.

Two research teams have different opinions regarding the number of paradoxidine species close to the base of the Miaolingian in Morocco and Spain. Geyer & Vincent (2015) recognized five species based on a mosaic of overlapping characters that include some relative length and width ratios, qualitative descriptions of cranidial and pygidial outlines, and relief observations. In contrast, Álvaro et al. (2018) conducted a morphometric analysis of all these specimens from the Cambropallas telesto acme level of the Assemame quarry and concluded that the Moroccan material had been taxonomically over-split and was represented by only two species, Acadoparadoxides mureroensis and A. nobilis. Subsequently, Geyer et al. (2019) commented that we had not analysed some diagnostic characters, and applied the stratigraphic setting of their morphospecies as a diagnostic character for taxonomic identification. After sampling the Cambropallas telesto acme level in the Taroucht quarry, where the other team purchased its collection, and re-analysing the diagnostic characters claimed by Geyer et al. (2019), our conclusions are maintained: (i) morphometric values of several paratype specimens fall outside the purported ranges of diagnostic characters; (ii) all 2D morphometric analyses incorporating the diagnostic characters of the morphospecies are unable to detect interspecific differences, except for A. nobilis; and (iii) the slight concavity displayed by some pygidia, strongly controlled by preservation, is in need of 3D biometrical analysis. Hence, our proposed synonymy should be maintained until 3D statistical analyses are available on material preserved in carbonate or concretions.

Two-dimensional flexural backstripping and thermal modelling (assuming laterally variable stretching) is applied along regional depth-converted interpreted seismic profiles from the Laxmi Basin in the Arabian Sea. Results from reverse post-rift flexural modelling reveal considerable basin-wide subsidence in response to the crustal geodynamics during and after the last extensional phase. Unloading of the stratigraphy allows us to estimate the degree of laterally varying extension, assuming thermal subsidence and pure shear. High degrees of extension in the basin centre predict considerable water depths at the time of rift cessation, consistent with deep drilling data. We suggest that regional extension prior to Paleocene time could have fuelled variable subsidence in the Laxmi Basin but that extension is less than seen in typical oceanic lithosphere. Volcanic loading by the seamounts shortly after extension has flexed the basin and implies an effective elastic thickness (Te) at that time of ∼6 km. Reconstruction of the seamount top near sea level at the end of emplacement indicates no major transient uplift potentially linked to the Deccan mantle plume activity. Backstripping of post-rift sediments from interpreted seismic profiles supports the presence of a hyper-thinned crust underneath the Laxmi Basin, with β factors reaching >7 in the basin centre and ∼3 across much of the basin width. Computations of decompacted sediment accumulation rates in light of new results from IODP Expedition 355 show that basin sedimentation peaked during early–middle Miocene time, possibly coeval with uplift and erosion of the Himalayan–Tibetan Plateau driven by strong summer monsoon rains.

The Middle Jurassic – Early Cretaceous period witnessed the emergence of some major representatives of modern continental vertebrate groups (stem lissamphibians, squamates, therian mammals and birds) and angiosperms, at a time when fragmentation of Pangaea was underway. The successive Moroccan microvertebrate faunas of Ksar Metlili (?Berriasian) and Guelb el Ahmar (Bathonian) from the Anoual Syncline significantly improve our poor knowledge of Gondwanan and especially African palaeobiodiversity at this time. They are among the richest known from the Mesozoic of Gondwana, and are well placed in northwestern Africa to record faunal interchanges with Laurasia. Here we focus on the Ksar Metlili fauna, first documented in the 1980s and most recently resampled in 2010, which produced 24 541 microremains representing 47 species of 8 main groups (Chondrichthyes, Actinopterygii, Sarcopterygii, Lissamphibia, Lepidosauromorpha, Testudinata, Archosauromorpha and Synapsida). It includes remarkable taxa: the oldest stem boreosphenidan mammals from Gondwana, probably some of the last non-mammaliaform cynodonts, a basal ornithischian, possibly freshwater teleosaurid crocodylomorphs, and some of the rare occurrences of choristoderes and albanerpetontids in Gondwana. Comparison of the Ksar Metlili fauna with that of Guimarota (Kimmeridgian, Portugal) further provides evidence of numerous shared taxa of Laurasian affinities, in contrast to the occurrence of few taxa with Gondwanan affinities. This suggests complex palaeobiogeographical relationships – implying both vicariance and dispersal events – of North Africa within Gondwana at the Jurassic–Cretaceous transition. Finally, the faunal similarities with the Guelb el Ahmar fauna question the Cretaceous age of the Ksar Metlili fauna, suggesting an alternative possible Late Jurassic age.

We studied the upper Permian and Lower Triassic deposits from the northern and northwestern marginal part of the Holy Cross Mountains (SE part of the Central European Basin or CEB, Poland) to examine stratigraphic continuity between these two systems, and to revise the currently existing stratigraphic framework. A previously existing informal lithostratigraphic scheme has been revisited and placed in a broader chronostratigraphic and palaeoenvironmental context. Sedimentary continuity across the Permian–Triassic (P/T) boundary has been confirmed by the presence of Lueckisporites virkkiae Bc morphological norm and Lundbladispora obsoleta–Protohaploxypinus pantii palynomorphs. Facies development reflects an interplay between climatic variations and tectonism during late Permian – Early Triassic time. The P/T boundary was placed between the Siodła Formation and overlying Szczukowice and Jaworzna formations, which coincides with the classical Zechstein–Buntsandstein boundary in the SE part of the CEB. The facies changes recorded in the studied terrestrial succession of the P/T boundary shed light on the environmental dynamic prior, during and after one of the biggest biotic crises in Earth’s history.

A review of biodiversity curves of marine organisms indicates that, despite fluctuations in amplitude (some large), a large-scale, long-term radiation of life took place during the early Palaeozoic Era; it was aggregated by a succession of more discrete and regionalized radiations across geographies and within phylogenies. This major biodiversification within the marine biosphere started during late Precambrian time and was only finally interrupted in the Devonian Period. It includes both the Cambrian Explosion and the Great Ordovician Biodiversification Event. The establishment of modern marine ecosystems took place during a continuous chronology of the successive establishment of organisms and their ecological communities, developed during the ‘Cambrian substrate revolution’, the ‘Ordovician plankton revolution’, the ‘Ordovician substrate revolution’, the ‘Ordovician bioerosion revolution’ and the ‘Devonian nekton revolution’. At smaller scales, different regional but important radiations can be recognized geographically and some of them have been identified and named (e.g. those associated with the ‘Richmondian Invasion’ during Late Ordovician time in Laurentia and the contemporaneous ‘Boda event’ in parts of Europe and North Africa), in particular from areas that were in or moved towards lower latitudes, allowing high levels of speciation on epicontintental seas during these intervals. The datasets remain incomplete for many other geographical areas, but also for particular time intervals (e.g. during the late Cambrian ‘Furongian Gap’). The early Palaeozoic biodiversification therefore appears to be a long-term process, modulated by bursts in significant diversity and intervals of inadequate data, where its progressive character will become increasingly clearer with the availability of more complete datasets, with better global coverage and more advanced analytical techniques.

The Tarim Basin is the major source of aeolian dust in the northern hemisphere. Glacial activity in the mountains, transportation by rivers and homogenization by wind are believed to be responsible for dust production within the basin. However, the major source(s) and homogenization process(es) are not clear. Moreover, provenance studies on fine fractions have never been conducted. Here, we measured electron spin resonance (ESR) signal intensity and the crystallinity index of quartz in fine (< 16 μm) and coarse (> 64 μm) fractions of river sediments, dry lake sediments and mountain loess to examine the process(es) that produce aeolian dust. The result suggests that the coarse fraction of the river sediment was derived from the bedrock in the drainage area. The ESR signal intensity and crystallinity index of the fine fraction of river sediments from the Tian Shan Mountains and mountainous rivers in the westernmost Kunlun and Pamir mountains are also similar to the coarse fraction, suggesting the same sources. However, the ESR signal intensity and crystallinity index of the fine fraction of river sediments from the Kunlun Mountains are different from the coarse fraction and converge towards values close to the average for the fine fraction of river sediments and mountain loess. Convergence of the ESR and crystallinity index values for the fine fraction of river sediments from the Kunlun Mountains can be explained by contamination of the river sediments by aeolian dust. The convergent values resulted from the homogenization of fine detrital material by repeated recycling within the basin.