Search

The geodynamic process from the evolution of supercontinent has distinct isotope characteristics explorable using zircon Hf isotopic composition. Since Peninsular Malaysia associates with Gondwana dispersal and Pangaea formation, analyzing the U-Pb and Hf-isotopic content of its 500–200 Ma magmatic zircon could reveal the signal left by the transitional geodynamic process between the supercontinents. We collected two groups of magmatic rocks from West Malaya: Ordovician meta-volcanics (n = 8), and Triassic Main Range granitoid province (MRGP) (n = 6); and three groups from East Malaya: Carboniferous meta-volcanics (n = 2), Permian-Triassic Eastern granite province (EGP) (n = 6), and Permian-Triassic EGP volcanics (n = 8). Difference in magmatic zircon Hf isotopic crustal model ages uphold the previous rationale which separates Peninsular into two blocks: West Malaya (part of Sibumasu terrane) magmatic zircon Hf isotopic crustal model ages (Average TDM2: 1.3 Ga) are older than East Malaya (part of Chanthaburi-Sukhothai-Lincang arc of Indochina terrane) (Average TDM2: 0.9 Ga). During the final assembly of Gondwana from 500 to 450 Ma, West Malaya and East Malaya were at the outboard of Gondwana Proto-Tethys margin. The shift of East Malaya zircon Hf array towards higher eHf(t) (external orogenic system) after ca.370 Ma may infers Paleo-Tethys ocean broadening and East Malaya separation from Gondwana. The 370–350 Ma juvenile zircon Hf isotopic composition in East Malaya is a significant improvement over radiolarian age to show the broadening and subduction of the Paleo-Tethys ocean between the two terranes. After ca.280 Ma, East Malaya zircon Hf array shifted towards lower eHf(t) (internal orogenic system). Coinciding with the Indosinian collision at ca.230 Ma, crustal reworking signal increases in both blocks, signifying the end in Peninsular Malaysia Gondwana to Pangaea transitional geodynamic process. As the Paleo-Tethys segment was completely subducted after 230 Ma, the peninsular crustal thickening starts from 230 to 218 Ma. The post-collision phase would begin at ca.215 Ma.

Supercontinents signify self-organization in plate tectonics. Over the past ~2 billion years, three major supercontinents have been identified, with increasing age: Pangaea, Rodinia and Columbia. In a prototypal form, a cyclic pattern of continental assembly and breakup likely extends back to ~3 billion years ago, albeit on the smaller scale of Archaean supercratons, which, unlike global supercontinents, were tectonically segregated. In this Review, we discuss how the emergence of supercontinents provides a minimum age for the onset of the modern global plate tectonic network, whereas Archaean supercratons might reflect an earlier geodynamic and nascent tectonic regime. The assembly and breakup of Pangaea attests that the supercontinent cycle is intimately linked with whole-mantle convection. The supercontinent cycle is, consequently, interpreted as both an effect and a cause of mantle convection, emphasizing the importance of both top-down and bottom-up geodynamics, and the coupling between them. However, the nature of this coupling and how it has evolved remains controversial, resulting in contrasting models of supercontinent formation, which can be tested by quantitative geodynamic modelling and geochemical proxies. Specifically, which oceans close to create a supercontinent, and how such predictions are linked to mantle convection, are directions for future research. Repeated amalgamation and dispersal of continents over Earth history is known as the supercontinent cycle; however, the geodynamic processes driving this cyclicity remain debated. This Review synthesizes observations, plate reconstructions and geodynamic models of supercontinent, and older Archaean supercraton, cycles.

Herbivory is a common ecological function among extant lepidosaurs, but little is known about the origin of this feeding strategy within Lepidosauria. Here we describe a sphenodontian (Lepidosauria) from the Late Triassic of western North America, Trullidens purgatorii n. gen. n. sp., that reveals new aspects of the earliest radiation of herbivorous lepidosaurs. This taxon is represented by an isolated lower jaw with robust structure bearing transversely widened dentition and extensive wear facets, suggesting a masticatory apparatus specialized for herbivory. An unusual 'incisor-like' tooth is present at the anterior end of the jaw; a unique feature among lepidosaurs, this tooth is convergent with the incisors of extant rodents and lagomorphs. Phylogenetic analyses support the placement of this taxon within opisthodontian sphenodontians, a group sharing derived cranio-dental morphologies specialized for herbivory. The new taxon was recovered in a recently discovered and unnamed series of Upper Triassic strata in southeastern Colorado, USA, exposed in Canyons incised by the Purgatoire River and its tributaries. These strata comprise a dominantly red-bed sequence of conglomerates, sandstones, and siltstones deposited in a fluvio-lacustrine setting, preserving a Late Triassic biota of invertebrate and vertebrate ichnofossils, plant macrofossils, bony fish, temnospondyl amphibians, and reptiles. We use aetosaur osteoderms as biostratigraphic links to the nearby Chinle Formation of Arizona, USA, establishing a middle Norian age for these strata. The presence of an opisthodontian from western equatorial Pangaea in the Norian Stage reveals a near-global radiation of this clade across the Pangaean supercontinent during the Late Triassic. UUID: http://zoobank.org/A737c03f-863a-488e-a860-5cc914548774. Virginia Tech Paleobiology Group Published version M.R. Stocker and S.J. Nesbitt of the Virginia Tech Paleobiology Group provided funding for and conducted mu CT scanning, which was conducted at the Duke Shared Instrumentation Facility and facilitated by J. Gladman. J. Autry, the Southeast Colorado Project Director at The Nature Conservancy, facilitated access to the J.E. Canyon Ranch and provided logistical support, supplies, and housing for the authors. B. Preston, S. Korbitz, B. Small, and Y. Huang assisted in field work. The Virginia Tech Paleobiology Research Group provided useful critiques and suggestions for figures in the manuscript. M. R. Stocker provided useful critiques and discussions on the manuscript. W.G. Parker of Petrified Forest National Park provided assistance in identifying aetosaur osteoderms. K. MacKenzie and J. Sertich of the DMNH facilitated curation of specimens used in this study. B. Creisler provided valuable etymological assistance. D. Whiteside and an anonymous reviewer provided valuable reviews of the manuscript. Public domain – authored by a U.S. government employee

A fragment of Hadean continental crust has been postulated to underlie the North China Craton based on the discovery of >3.8 Ga detrital zircons, but these detrital zircons may be transported from a lateral source. Here we report new U Pb ages of 3823 to 230 Ma for zircon xenocrysts directly from Cretaceous granites (129 Ma), which rules out a lateral source. Our results for the first time demonstrate the existence of 3.85 Ga crustal precursors beneath the southern North China Craton based on the Hf isotopic compositions of the 3.82 Ga zircon. The crustal precursors might be a granitic source that was produced by the wet melting of ancient continental crust. We further show that the southern North China Craton has experienced the global Columbia, Gondwana, and Pangaea supercontinent events, based on the inherited zircon age groups of 2017–1896 Ma, 1792–1776 Ma, 584–570 Ma and 251–230 Ma. These Eoarchaean to Triassic U Pb ages document the evolution of the early continental crust and the geological process in the development of the North China Craton.

Gabbros and ultramafic rocks of the Huargualla Gabbro unit exposed in faulted slivers along the western Cordillera Real of Ecuador crystallised between 623and531 Ma (40Ar/39Ar dates), were derived from asthenospheric sources with minor crustal contamination, and form part of the Central Iapetus Magmatic Province. These rocks formed in an early rift environment during the opening of the Iapetus Ocean, and represent the only igneous record of Iapetus rifting north of the Huancabamba deflection (5°S) in South America. The age and composition of the Huargualla Gabbro unit is consistent with the reconstruction of Tegner et al. (2019) , which juxtaposes Baltica and northwestern Gondwana within Panotia. 206Pb/238U dates of detrital zircons combined with fossil assemblages shows that the Chiguinda unit of the Cordillera Real, and La Victoria Unit of the Amotape Complex were deposited during the Carboniferous. These new data, combined with previous studies of magmatism and sedimentation from southern Peru, Colombia and Venezuela, imply that the rocks of the Cordillera Real were in the Ordovician and Carboniferous back-arcs, while the arcs occur in conjugate margins that separated during the Triassic rifting of Pangaea. Faulted remnants of Ordovician arc rocks in the Cordillera Central of Colombia are probably allochthonous, and have been displaced from an Ordovician margin that did not face the rifted crustal sections.

Chamberlin and Salisbury's assessment of the Permian a century ago captured the essence of the period: it is an interval of extremes yet one sufficiently recent to have affected a biosphere with near-modern complexity. The events of the Permian – the orogenic episodes, massive biospheric turnovers, both icehouse and greenhouse antitheses, and Mars-analog lithofacies – boggle the imagination and present us with great opportunities to explore Earth system behavior. The ICDP-funded workshops dubbed “Deep Dust,” held in Oklahoma (USA) in March 2019 (67 participants from nine countries) and Paris (France) in January 2020 (33 participants from eight countries), focused on clarifying the scientific drivers and key sites for coring continuous sections of Permian continental (loess, lacustrine, and associated) strata that preserve high-resolution records. Combined, the two workshops hosted a total of 91 participants representing 14 countries, with broad expertise. Discussions at Deep Dust 1.0 (USA) focused on the primary research questions of paleoclimate, paleoenvironments, and paleoecology of icehouse collapse and the run-up to the Great Dying and both the modern and Permian deep microbial biosphere. Auxiliary science topics included tectonics, induced seismicity, geothermal energy, and planetary science. Deep Dust 1.0 also addressed site selection as well as scientific approaches, logistical challenges, and broader impacts and included a mid-workshop field trip to view the Permian of Oklahoma. Deep Dust 2.0 focused specifically on honing the European target. The Anadarko Basin (Oklahoma) and Paris Basin (France) represent the most promising initial targets to capture complete or near-complete stratigraphic coverage through continental successions that serve as reference points for western and eastern equatorial Pangaea.

Long-term time-series are a fundamental prerequisite to understand and detect climate shifts and trends. Understanding the complex interplay of changing ocean variables and the biological implication for marine ecosystems requires extensive data collection for monitoring and hypothesis testing and validation of modelling products. In marginal seas, such as Mediterranean Sea, there are still monitoring gaps, both in time and in space. To contribute filling these gaps, an extensive dataset of dissolved inorganic nutrients profiles (nitrate, NO3; phosphate, PO43−; and silicate, SiO2) have been collected between 2004 and 2017 in the Western Mediterranean Sea and subjected to quality control techniques to provide to the scientific community a publicly available, long-term, quality controlled, internally consistent biogeochemical data product. The database includes 870 stations of dissolved inorganic nutrients sampled during 24 cruises, including temperature and salinity. Details of the quality control (primary and secondary quality control) applied are reported. The data are available in PANGAEA (https://doi.org/10.1594/PANGAEA.904172, Belgacem et al. 2019).

The fossil trunks and rhizomes of Osmundaceae provide important information about its evolutionary history. Due to limited records of the Mesozoic trunks and rhizomes in the Eurasia of the Northern Hemisphere, our understanding on the fossil diversity of the Osmundaceae is hindered. Two new species of the Osmundaceae trunks, Osmundacaulis asiatica sp. nov. and Osmundacaulis sinica sp. nov. representing the first discovery of the Mesozoic tree fern genus Osmundacaulis in Eurasia, are described from Wudalianchi and Qiqihar, Heilongjiang Province, Northeast China, which enriches the plant diversity of the Osmundaceae in the Eurasia, and provides vital evidence for studying the distribution, radiation and evolution of the genus during the Cretaceous. The fossil records suggest that Osmundacaulis species may have evolved from a common ancestor, which first appeared in the Australian portion of Pangaea, and then spread to ancient northern North America and ancient East Asia. Since then, they developed into different species through their own evolutionary lines. The Chinese species have a special local feature that the outer cortex is thicker than the inner cortex, in contrast with reported Osmundacaulis species having thinner outer cortex and thicker inner cortex. Long-term geographic isolation may have led to the radiation of diverse Osmundacaulis species and the appearance of region-specific features, such as the thick outer cortex and the thin inner cortex of the Chinese species. Among all reported Osmundacaulis species, the two new species found in China, O. nerii from the Jurassic of Australia and the O. lemonii from the Jurassic of the USA, have special groups of mucilage-sacs inside sclerenchyma ring of petiole base. Mucilage sacs probably originated independently among taxonomic groups, representing convergent adaptations to similar habitats, rather than indicating genetic inheritance from a common ancestor.

U Pb geochronology along a north-south transect from central Sonora to northern Sinaloa in northwestern Mexico indicates several changes in provenance sources through time and space. Lower Cambrian arenites of the Proveedora Quartzite yield a single main age peak at 1075 Ma with minor Paleoproterozoic contribution. Arenites from the Sonobari Complex of southwestern Sonora-northwestern Sinaloa, purportedly assigned to the early Paleozoic, yield main peaks at 1424, 1662, and 1736 Ma, probably derived from the Yavapai and Mazatzal provinces, which are pervasively intruded by early Mesoproterozoic granites coeval to those forming the Granite-Rhyolite Province. Lower to Upper Ordovician units deposited on shelf, slope, and abyssal environments display very similar zircon age patterns, with main peaks ca. 2700 and 1850 Ma, indicating a large drainage system arising from the Archean cratons of Laurentia such as the Wyoming or Superior Provinces, and Paleoproterozoic sources similar to the Trans-Hudsonian orogen, which are older than the Yavapai Province. The Rio Fuerte quartzites from southern Sonora-northern Sinaloa contain main peaks at 534, 542, and 637 Ma whose sources may be peri-Gondwanan blocks similar to Avalonia or Carolina terranes. A minor peak at 475 Ma suggests input from igneous suites reported from the Acatlan Complex in southern Mexico. U Pb geochronology permit inference of a late Paleozoic collisional orogen in northwestern Mexico that was originated by the collision of Gondwanan blocks against southern Laurentia and outline the boundary between terranes related to continental blocks in the Pangaea supercontinent.

Deep lithospheric processes associated with the formation of major orogens, including the removal of lower crust and underlying mantle through delamination associated with orogen building are poorly constrained. With a view to evaluate the potential link between deep geodynamic processes and magmatic events, we performed in situ zircon Hf-O-Li isotopic analyses of granitoids from the Eastern and Western Junggar, Altai and Beishan orogens, within the Central Asian Orogenic Belt (CAOB). The eHf(t) and δ18O values of magmatic zircons crystallized during 443 Ma and 252 Ma indicate diverse and heterogeneous magma sources. The corresponding δ7Li peaks at ~440 Ma and ~250 Ma, suggesting two distinct high-temperature magmatic events. Based on a comparison with global data, we argue that large-scale delamination formed through Gondwana and Pangaea supercontinent assembly, may have occurred at Ordovician to Silurian boundary (OSB) and Permian to Triassic boundary (PTB), which we term as super-delamination. The subsequent widespread magmatism and volcanism might have made significant impact on the Earth surface ecosystems, ultimately leading to the OSB and PTB mass extinction events. We propose super-delamination as a potential mechanism to explain the link between Earth's internal and external processes, thus providing novel insights into the trigger for mass extinction events.

The Earth’s mantle is currently divided into the African and Pacific domains, separated by the circum-Pacific subduction girdle, and each domain features a large low shear-wave velocity province (LLSVP) in the lower mantle. However, it remains controversial as to whether the LLSVPs have been stationary through time or dynamic, changing in response to changes in global subduction geometry. Here we compile radiogenic isotope data on plume-induced basalts from ocean islands and oceanic plateaus above the two LLSVPs that show distinct lead, neodymium and strontium isotopic compositions for the two mantle domains. The African domain shows enrichment by subducted continental material during the assembly and breakup of the supercontinent Pangaea, whereas no such feature is found in the Pacific domain. This deep-mantle geochemical dichotomy reflects the different evolutionary histories of the two domains during the Rodinia and Pangaea supercontinent cycles and thus supports a dynamic relationship between plate tectonics and deep-mantle structures. Earth’s deep-mantle domains are geochemically distinct. The African domain is enriched in subducted material, which suggests a different history from the Pacific domain and a dynamic relationship between plate tectonics and deep-mantle structures.

Carboniferous–Permian strata in basins within the Central Pangean Mountains in France archive regional paleoequatorial climate during a unique interval in geological history (Pangea assembly, ice-age collapse, megamonsoon inception). The voluminous (∼1.5 km) succession of exclusively fine-grained red beds that comprises the Permian Salagou Formation (Lodève Basin, France) has long been interpreted to record either lacustrine or fluvial deposition, primarily based on a local emphasis of subaqueous features in the upper ∼25% of the section. In contrast, data presented here indicate that the lower-middle Salagou Formation is dominated by up to 15-m-thick beds of internally massive red mudstone with abundant pedogenic features (microscale) and no evidence of channeling. Up-section, limited occurrences of ripple and hummocky cross-stratification, and mudcracks record the intermittent influence of shallow water, but with no channeling nor units with grain sizes exceeding coarse silt. These data suggest that the most parsimonious interpretation for the Salagou Formation involves eolian transport of the sediment and ultimate deposition as loess in shallow, ephemeral lacustrine environments. Provenance analyses of the Salagou Formation indicate coarse-grained protoliths and, together with geochemical proxies (chemical index of alteration [CIA] and τNa) that correspond respectively to a low degree of chemical weathering and a mean annual temperature of ∼4 °C, suggest that silt generation in this case is most consistent with cold-weathering (glacial and associated periglacial) processes in the Variscan highlands. Together with previous studies that detailed voluminous Permian loess in western equatorial Pangea, this work shows a globally unique distribution of dust at low latitudes that can be linked either directly to glaciated alpine terranes or to reworked and deflated deposits of other types (e.g., fluvial outwash) where fine-grained material was originally generated from glacial grinding in alpine systems. These results further support a revised model for early Permian climate, in which extratropical ice sheets coexisted with a semiarid tropics that may have hosted significant ice at moderate elevation.

The Southern Ocean may contribute a considerable amount to the proposed global network of marine protected areas (MPAs) that should cover about 10 % of the world's oceans in 2020. In the Antarctic, the Commission for the Conservation of Antarctic Marine Living Resources (CCAMLR) is responsible for this task, and currently Germany leads a corresponding scientific evaluation of the wider Weddell Sea region. Compared to other marine regions within the Southern Ocean, the Weddell Sea is exceptionally well investigated. A tremendous amount of data and information has been produced over the last 4 decades. Here, we give a systematic overview of all data sources collected in the context of the Weddell Sea MPA planning process. The compilation of data sources is comprised of data produced by scientists and institutions from more than 20 countries that were either available within our institutes, downloaded via data portals or transcribed from the literature. It is the first compilation for this area that includes abiotic data, such as bathymetry and sea ice, and ecological data from zooplankton, zoobenthos, fish, birds and marine mammals. All data layer products based on this huge compilation of environmental and ecological data are available from the data publisher PANGAEA via the six persistent identifiers at https://doi.org/10.1594/PANGAEA.899595 (Pehlke and Teschke, 2019), https://doi.org/10.1594/PANGAEA.899667 (Teschke et al., 2019a), https://doi.org/10.1594/PANGAEA.899645 (Teschke et al., 2019b), https://doi.org/10.1594/PANGAEA.899591 (Teschke et al., 2019c), https://doi.org/10.1594/PANGAEA.899520 (Pehlke et al., 2019a) and https://doi.org/10.1594/PANGAEA.899619 (Pehlke et al., 2019b). This compilation of data sources including the final data layer products will serve future research and monitoring well beyond the current MPA development process.

Direct observations of marine microbial metabolism are sparse in the Arctic, particularly under sea ice during winter. This paper presents the first observations of Arctic winter microbial activity under sea ice in a west Greenland fjord (Lillefjord, ∼ 70∘ N). Here, measured changes in dissolved oxygen (DO) content in light and dark in situ incubations were used to calculate net community productivity, respiration and photosynthesis rates. Data were collected at two fully ice covered sites during February 2013, shortly after the end of the polar night. Averaged over the full study period, dark incubations showed statistically significant decreases in DO of -0.36±0.24 (near shore) and -0.09±0.07 g O2 m−3 d−1 (fjord centre), indicating respiration rates that were 2–20 times greater than rates previously reported under sea ice in the Arctic. Meanwhile, a lack of significant evidence for photosynthesis suggests that the rate of photosynthesis – if it was occurring – was much lower than that of respiration. The data also show no significant evidence of a temporal trend in metabolism rates over the study period; however, ambient seawater DO increased significantly at the fjord centre (0.023±0.013 g O2 m−3 d−1), possibly attributable to processes not occurring in the incubations (such as sea ice algal photosynthesis). These data may improve our understanding of microbial activity in the fjord during winter, and its contribution to Arctic ecosystems under present and future conditions. The data are archived at PANGAEA (https://doi.org/10.1594/PANGAEA.906332, Chandler and Mackie, 2019; https://doi.org/10.1594/PANGAEA.912677, Chandler and Mackie, 2020).

The Wordiekammen Formation, a carbonate ramp on Spitsbergen developed on the Northern Pangaean margin in Moscovian (Carboniferous) through Sakmarian (Permian) time at a paleolatitude of 30–35° N. The study site on the Nordfjorden High was isolated from any source of fluvio-deltaic input, such that detrital material that occurs in this system experienced eolian transport, thus forming a proxy for atmospheric dust loading. We analyzed two intervals, of Moscovian (10 m) and Asselian (27 m) age, at 20 cm resolution, and identified five mid-ramp subtidal facies organized in upwardly shallowing, high-frequency sequences 3–5 m thick. High-frequency sequence boundaries commonly exhibit signs of subaerial exposure (e.g., Microcodium) developed atop subtidal facies, recording glacioeustatic falls (glacial phases), although the Moscovian section has a severe karst overprint attributable to prolonged exposure on a paleohigh. Samples were processed to isolate the silicate-mineral fraction (SMF), which includes both detrital silicate material and authigenic silica mostly in the form of (fine-sand-size) doubly terminated quartz crystals. Detrital cores in these crystals, together with other evidence, indicate recrystallization from fine-grained (silt- and clay-size) dust. Analysis of the dust record demonstrates that the Asselian (peak icehouse) had a significantly higher atmospheric dust load than the Moscovian (moderate icehouse). In the Asselian interval, dust input varies commensurate with glacial–interglacial cyclicity. Highest dust contents correspond to transgressive facies immediately above sequence boundaries, indicating peak atmospheric dust loading at lowstand to incipient interglacial times. Provenance data from detrital-zircon and whole-rock geochemistry indicate two distinct source regions for the dust. Dust from the Moscovian and lower Asselian intervals reflects a continental island-arc signature consistent with sourcing from the basement of northeast Greenland. Dust from the upper Asselian interval is more consistent with recycling from Devonian and Carboniferous strata of the east Greenland Caledonides, likely deflated from fluvial systems draining this orogenic system, indicating an expansion of regions of eolian deflation.

The article presents the climatological dataset from the Polish Polar Station Hornsund located in the southwest part of Spitsbergen – the biggest island of the Svalbard archipelago. Due to a general lack of long-term in situ measurements and observations, the High Arctic remains one of the largest climate-data-deficient regions on the Earth. Therefore, the described time series of observations in this paper are of unique value. To draw conclusions on the climatic changes in the Arctic, it is necessary to analyse and compare the long-term series of continuous, in situ observations from different locations, rather than relying on the climatic simulations only. In recent decades, rapid environmental changes occurring in the Atlantic sector of the Arctic are reflected in the data series collected by the operational monitoring conducted at the Hornsund station. We demonstrate the results of the 40-year-long series of observations. Climatological mean values or totals are given, and we also examined the variability of meteorological variables at monthly and annual scale using the modified Mann–Kendall test for trend and Sen's method. The relevant daily, monthly, and annual data are provided on the PANGAEA repository (https://doi.org/10.1594/PANGAEA.909042, Wawrzyniak and Osuch, 2019).

We present a collection of magnetic field absolute measurements performed by the early Soviet magnetic satellite missions Kosmos-49 (1964) and Kosmos-321 (1970). A total of 17 300 measured values are available for the Kosmos-49 mission, covering homogeneously 75 % of the Earth's surface between 49∘ latitude north and south. About 5000 measured values are available for the Kosmos-321 mission, covering homogeneously 94 % of the Earth's surface between 71∘ latitude north and south. The data are available at PANGAEA (Krasnoperov et al., 2020, https://doi.org/10.1594/PANGAEA.907927).

We present a high-resolution airborne radar data set (EGRIP-NOR-2018) for the onset region of the Northeast Greenland Ice Stream (NEGIS). The radar data were acquired in May 2018 with Alfred Wegener Institute’s multichannel ultra-wideband (UWB) radar mounted on the Polar6 aircraft. Radar profiles cover an area of ~24000 km2 and extend over the well-defined shear margins of the NEGIS. The survey area is centred at the location of the drill site of the East Greenland Ice-Core Project (EastGRIP) and several radar lines intersect at this location. The survey layout was designed to: (i) map the stratigraphic signature of the shear margins with radar profiles aligned perpendicular to ice flow, (ii) trace the radar stratigraphy along several flow lines and (iii) provide spatial coverage of ice thickness and basal properties. While we are able to resolve radar reflections in the deep stratigraphy, we can not fully resolve the steeply inclined reflections at the tightly folded shear margins in the lower part of the ice column. The NEGIS is causing the most significant discrepancies between numerically modelled and observed ice surface velocities. Given the high likelihood of future climate and ocean warming, this extensive data set of new high-resolution radar data in combination with the EastGRIP ice core will be a key contribution to understand the past and future dynamics of the NEGIS. The EGRIP-NOR-2018 radar data products can be obtained at the PANGAEA Data Publisher (https://doi.pangaea.de/10.1594/PANGAEA.928569; Franke et al. 2021a).

The Guajira Arch is located in the northernmost portion of South America and holds the record of several stages of magmatism and metamorphism. We performed LA-ICP-MS U–Pb zircon geochronology coupled with Lu–Hf isotope geochemistry on 11 samples from a high-grade gneissic basement hosting interleaved complexes of younger meta-granitoids and meta-sediments to unravel its tectono-metamorphic evolution. The oldest rocks correspond to a Rodinia-type basement at ca. 1100-880 Ma, affected by mafic magmatism during the Permian at ca. 272 Ma, anatexis during the Carnian at ca. 230 Ma, updoming and the formation of an extensional detachment fault during the Norian at ca. 224 Ma concluding with Jurassic magmatism since ca. 190 Ma. Trace element geochemistry shows that Triassic zircons are depleted in HREE and yield lower Th/U ratios than Jurassic zircons enriched both in HREE, Yb, and Y. Hf systematics indicates a Triassic to Jurassic evolution towards more radiogenic compositions. The lithological associations, structural setting, U–Pb ages, and Hf isotope geochemistry of the Triassic-Jurassic rocks at the Guajira Arch characterize an active margin setting of a hot orogenic belt in NW-Gondwana, comprising the Central Cordillera of Colombia, the Santa Marta Massif, the Merida Andes, the Perija Range, the Santander Massif and the para-autochthonous terranes south of the Ouachita-Marathon Suture (Oaxaquia, Acatlan, and Maya), and thus vindicate the existence of a conjugate margin with Laurentia until the Late Triassic, preceding the breakup of western Pangaea. The Triassic anatectites and Jurassic granitoids from the Guajira Arch yield Proterozoic Hf TDMi ages which are indistinguishable from the autochthonous Proterozoic basement and thus render an allochthonous origin by terrane accretion highly improbable. Instead, these data point to melting of the continental crust by the incorporation of primitive material reflecting a two-stage process at the boundary of a large underlying mantle convection cell (i) Triassic slab steepening, subduction arrest, updoming anatexis at ca. 230-223 Ma and (ii) Early Jurassic arc-magmatism at ca. 190-165 Ma due renewed convergence. Furthermore, we propose that the structural setting, lithology, and isotope geochemistry of the Guajira Arch units, fit into the style of a cordilleran core-complex emplaced in a roll-back extensional setting preceding Pangaea break-up.

Tethyan ophiolites have played a major role in the development of the ophiolite concept during the past 200 years, and contributed significantly to the formulations of the suprasubduction-zone (SSZ) ophiolite paradigm and the plate-tectonics theory. Their melt evolution and magmatic construction witnessed the dispersal of the supercontinent Pangaea via continental rifting and seafloor spreading, opening and closure of multiple seaways in an eastward widening, latitudinal ocean basin (Neotethys), and deep mantle recycling processes through subduction-zone tectonics and plume activities. Neotethyan ophiolites are highly diverse in their crustal–mantle structures and compositions, pointing to major differences in their melt sources and tectonic settings of magmatic construction. The papers in this thematic set demonstrate these differences in the Neotethyan ophiolite record through new structural, geochemical, isotopic and geochronological data and interpretations. The Jurassic Western Alpine Ophiolites formed in a narrow basin (Alpine Tethys) that developed between Europe and North Africa–Adria–Iberia. Their peridotites represent exhumed, continental lithospheric mantle. The Triassic, Jurassic and Cretaceous ophiolites east of Adria formed in different Neotethyan seaways, and their SSZ magmatic construction involved multiple episodes of melting, depletion and refertilization of subduction-modified oceanic mantle. The Late Cretaceous peri-Arabian and peri-Indian ophiolites, which are discontinuously exposed along a c. 9000 km long belt from SW Anatolia to SE Tibet, formed above a Trans-Tethyan subduction–accretion system within Southern Neotethys. Diachronous collisions of Arabia and India with this intraoceanic subduction–accretion system in the latest Mesozoic and the Paleogene (respectively) resulted in diachronous ophiolite emplacement in the Mediterranean and Tibetan–Himalayan orogenic belts. Thematic collection: This article is part of the ‘Tethyan ophiolites and Tethyan seaways collection’ available at: https://www.lyellcollection.org/cc/tethyan-ophiolites-and-tethyan-seaways

A silicified gymnospermous wood, Protophyllocladoxylon zhaobishanensis sp. nov., is described from the Induan (Lower Triassic) Jiucaiyuan Formation in Zhaobishan section, Shanshan County, southern Bogda Mountains, Xinjiang Uygur Autonomous Region, northwestern China. The pycnoxylic wood contains thick-walled tracheids and parenchymatous ray cells. It is characterized by uni- to triseriate araucarian radial tracheidal pitting, uniseriate rays, one to two large, simple pits in each cross-field, and uni- to biseriate tangential tracheidal pits. The presence of distinct and extensive growth rings in all fossil woods from the Induan of the research area were probably caused by the seasonal climate with great precipitation variability during the earliest Triassic in the Turpan–Hami Basin. This is also supported by the occurrence of Calcisols, vertic Calcisols, and calcic Argillisols from coeval deposits nearby. The occurrence of fossil wood with anatomical structures from the Induan confirms that woody gymnosperms, probably conifers, were crucial elements on the Early Triassic landscape in northeastern Pangaea. It appears that some gymnosperms had survived the end-Permian biotic crisis based on the continuous records of Protophyllocladoxylon-type woods from the Wuchiapingian (upper Permian) to Norian (Upper Triassic) in Bogda Mountains.

The increasing desertification in the continental interior of Pangaea during the Permian-Triassic transition was of fundamental importance in the Earth landscape and life evolution. In the west-central Pangaea, northern Brazil, acid-saline-lake systems were gradually succeeded by dry aeolian ergs due to intense continentalization in arid climate setting. Detailed facies and architectural analysis were applied in the Permian-Triassic succession of the Parnaiba Basin, and seven facies associations were recognized: (1) ephemeral lake, represented by greenish and reddish gray laminated mudstones interbedded with chert-rich fine-grained sandstones, (2) marginal dune field consisting of fine-to medium-grained sandstones with planar cross-bedding sets, (3) shallow perennial saline lake consisting dominantly of red laminated mudstones with discontinuous layers of sigmoidal sandstones, (4) playa lake/ dry mudflat represented by reddish laminated mudstones interbedded with limestone, marl and gypsum lenses, (5) sand sheet consisting of laterally continuous beds of fine-to medium-grained sandstones with convoluted lamination, synsedimentary faults/microfaults and adhesion structures, (6) dune field formed by fine-to medium-grained sandstones with large-scale cross-bedding sets, and (7) volcanic plain, consisting of basalts interbedded with aeolian sandstones. During middle Permian, the shallow to deep ephemeral lakes occurred in large plains in the tropical zone of western to central Pangaea. The cyclicity of wet and dry lacustrine phases was triggered by changes in the groundwater level, low subsidence rate, and low accommodation space. The prolonged dry stages were characterized by the advance of the marginal dune fields as well as the establishment of large desiccated areas. In the upper Permian, the continuous process of Pangaea amalgamation led to the uplift of central and equatorial regions resulting in the retreat of epicontinental seas. Thereafter, there was the appearance of large-scale closed basins and continental saline environments. The extreme aridity conditions favored the decline of these great lakes and the development of an extensive Triassic Erg. Sand sheets occurred in the marginal areas of the erg, containing abundant ephemeral ponds and dispersed aeolian dunes. Extensive dune fields advanced as a consequence of the sediment availability increase, whereas deflation surfaces were produced by the widespread output of sediments. The total interruption of sediment availability to the erg in the upper Triassic provided an extreme and regional deflation surface overlaid by eoJurassic volcanic rocks, associated with the Pangaea breakup.

The periodic dispersal and assembly of continental fragments has been an inherent feature of the continental crust. Based on the discovery of large-scale supercontinent cycle and the theory of plate tectonics, several supercontinents have been identified, such as Columbia/Nuna, Rodinia, Gondwana and Pangaea. Neoproterozoic magmatic events related to the break-up of Rodinia are globally well preserved. Although Neoproterozoic magmatic events were very weak in the North China Craton (NCC), they are crucial in reconstructing the geometries of the NCC and could facilitate the completion of the Neoproterozoic configuration of the supercontinent. In this study, c. 853–835 Ma magmatic rocks are identified in the western margin of the NCC. Precise zircon U–Pb age determination yields 206Pb/238U average ages of 835.5 ± 5.3 Ma (HL-39) and 853.7 ± 4.5 Ma (HL-30). In situ zircon Hf isotope compositions of the samples reveal that their parental magma was formed by the reworking of ancient crust evolved from Mesoproterozoic mantle. In summary, the discovery of Neoproterozoic magmatic rocks in the western margin of the NCC, and reported synchronous rocks in other parts of the NCC indicate that the NCC might be conjoined with the supercontinent Rodinia during the Neoproterozoic. This discovery is of significant help in unravelling the early Neoproterozoic history of the NCC and the evolution of the supercontinent Rodinia.

An integrated analysis in this study of paleogeographic, paleontologic, seismic and sedimentologic data has been used to explain the effect of the Pangaean megamonsoon on the whole Triassic (especially the Middle–Late Triassic Mungaroo Formation) in the North Carnarvon Basin, Northwest Shelf of Australia. Our results show that the three Triassic formations from bottom to top (Locker Shale, Mungaroo Formation and Brigadier Formation) comprise a complete depositional cycle and correspond to an undeveloped, strong, and weak monsoon periods, respectively. During the strong monsoon period of the Mungaroo Formation, the palynological evidences exhibited mixture spore-pollen characteristics of the hygrophytic assemblage (spore-pollen from the pteridophyte spores, seed ferns and cycads pollen in humid environment of lowlands and coastal plain) and the xerophytic assemblage (pollen from the drought tolerant plants of the interior mountainous areas). The sedimentary evidences of the Mungaroo Formation show low-angle shingled progradational seismic reflection configuration. The highly seasonal variations in precipitation during deposition of the Mungaroo Formation exhibited typical “sandwiched” depositional characteristics of coarse channels sandstone (fining-upward fluvial aggradational cycles (FACs) with poor to moderately sorting and angular to subangular roundness), organic mudstone and coal seam interbedded. Finally, in contrast to today's typical examples of Poyang Lake Delta, a shallow-water braided delta conceptual depositional model of the Mungaroo Formation is formed with a large proximal and distal delta plain, and small delta front. The model results serve mainly to indicate the importance of various climate-forming factors (climate, topography, eustatic), whereas tectonic activity unlikely played any significant role in this process.

Ronchi et al. (in press) comment on the stratigraphic, sedimentological, mineralogical and palaeontological analyses performed in the recently described Coll de Terrers Permian–Triassic terrestrial succession from the Catalan Pyrenees by Mujal et al. (2017a). The comment debates our interpretation of a succession of red-beds as Permian (Upper Red Unit, URU). Instead, the comment infers that the analysed succession is part of the regional upper Buntsandstein facies unit (Triassic), debating the proposed stratigraphic scheme by using the tectonic evolution as the main argument. Here, we clarify and present more details on the interpretation published in Mujal et al. (2017a). Based on this clarification and taking into account the comment, we arrive to the conclusion that the interpretation and inferences presented in Mujal et al. (2017a) are sound and justified. © 2018 Elsevier B.V.

This study reports diverse spiriferellid brachiopods from the Permian rocks of Svalbard and adjacent areas (Arctic Canada and Subpolar Urals of Russia) located at the northern margin of Pangaea. In...

Dinocephalians form an important component of the Guadalupian basal therapsid faunas of Pangaea. Most research undertaken on this clade has focused on the skull while postcranial research has lagge...

The Triassic–Jurassic boundary interval was characterised by the change from warm, semiarid–arid to a hot and humid climate in the Tethyan domain linked to input of greenhouse gases from the Central Atlantic Magmatic Province (CAMP) activity and Pangaea breakup. This study provides the very first outcrop evidences of palaeoclimatic evolution during the Triassic–Jurassic boundary interval in the then southern hemisphere, along the eastern margin of Gondwana facing the western Tethys. In the Tethyan Salt Range of Pakistan a succession of Upper Triassic dolomites, green-black shales (Kingriali Formation) to overlying Lower Jurassic quartzose sandstones, shales, laterites and conglomerates (Datta Formation) represents the sedimentary archives of this critical time interval. Bulk and clay mineralogy of the Upper Triassic shales indicate the presence of mainly illite while kaolinite is a minor component. The kaolinite content, a reflection of the mature stage of chemical weathering and hence hot–humid conditions, increases up-section in the overlying shales and sandstone–shale succession. The following laterite–bauxite horizons lack illite and are entirely composed of kaolinite, boehmite and haematite. The bulk rock geochemistry of the succession confirms a similar trend. The Chemical Index of Alteration (CIAmolar) displays an increasing trend from the Upper Triassic (CIA 68–80) to the overlying Lower Jurassic strata (CIA 90–97). The overall results for the succession reveal an increasing chemical maturity trend from Rhaetian to Hettangian thereby supporting a change from warm-arid to a hot and humid palaeoclimate, probably extreme greenhouse conditions. Similar changes in the clay mineralogy and sediment geochemistry across the Triassic–Jurassic boundary have been reported from basins across Europe. Thus the Salt Range provides sections from the southern hemisphere for correlations across the Triassic–Jurassic boundary.

The Middle–Late Permian reefs were formed in two paleogeographic realms: North Pangaea and Tethyan Realm. The basic reef builders in the first realm were representatives of Calcispongiae and Bryozoa; in the second realm, sphinctozoans, corals, and stromatoporoids. In these realms, various algae and cyanobacteria communities were of importance. Reef construction in the first realm associated with arid climatic conditions, isolation of water basins, and accumulation of salt-bearing sequences came to the end in the early Late Permian. Reef construction in the Tethyan Realm occurred in the Late Permian up to the Permian–Triassic boundary. The termination of reef construction was due to features of the reef ecosystem, which turned out to be unstable against the background of variations in the conditions and mass extinction at the Permian–Triassic boundary and dissociated before the termination of this extinction.

Hematite is the most abundant surficial iron oxide on Earth resulting from near-surface processes that make it important for addressing numerous geologic problems. While red beds have proved to be excellent paleomagnetic recorders, the early diagenetic origin of hematite in these units is often questioned. Here, we validate pigmentary hematite (“pigmentite”) as a proxy indicator for the Late Triassic environment and its penecontemporaneous origin by analyzing spectrophotometric measurements of a 14.5-My–long red bed sequence in scientific drill core CPCP-PFNP13-1A of the Chinle Formation, Arizona. Pigmentite concentrations in the red beds track the evolving pattern of the Late Triassic monsoon and indicate a long-term rise in aridity beginning at ∼215 Ma followed by increased oscillatory climate change at ∼213 Ma. These monsoonal changes are attributed to the northward drift of the Colorado Plateau as part of Laurentia into the arid subtropics during a time of fluctuating CO(2). Our results refine the record of the Late Triassic monsoon and indicate significant changes in rainfall proximal to the Adamanian–Revueltian biotic transition that thus may have contributed to apparent faunal and floral events at 216 to 213 Ma.

The Beaufort Group of the main Karoo Basin of South Africa records two major extinction events of terrestrial vertebrates in the late Palaeozoic. The oldest of these has been dated to the late Capitanian and is characterized by the extinction of dinocephalian therapsids and bradysaurian pareiasaurs near the top of Tapinocephalus Assemblage Zone. Faunal turnover associated with the extinction of dinocephalians is evident in vertebrate faunas from elsewhere in Pangaea but it can be best studied in the Karoo Basin, where exposures of the upper Abrahamskraal and lower Teekloof formations allow continuous sampling across the whole extinction interval. Here we present field data for several sections spanning the Capitanian extinction interval in the southwestern Karoo and discuss recent work to establish its timing, severity, and causes. A large collections database informed by fieldwork demonstrates an increase in extinction rates associated with ecological instability that approach that of the end-Permian mass extinction, and shows significant turnover followed by a period of low diversity. Extinctions and recovery appear phased and show similarities to diversity patterns reported for the end-Permian mass extinction higher in the Beaufort sequence. In the Karoo, the late Capitanian mass extinction coincides with volcanism in the Emeishan Large Igneous Province and may have been partly driven by short-term aridification, but clear causal mechanisms and robust links to global environmental phenomena remain elusive.

Moradisaurine captorhinid eureptiles were a successful group of high-fibre herbivores that lived in the arid low latitudes of Pangaea during the Permian. Here we describe a palaeoassemblage from the Permian of Menorca (Balearic Islands, western Mediterranean), consisting of ichnites of small captorhinomorph eureptiles, probably moradisaurines (Hyloidichnus), and parareptiles (cf.Erpetopus), and bones of two different taxa of moradisaurines. The smallest of the two is not diagnostic beyond Moradisaurinaeincertae sedis. The largest one, on the other hand, shows characters that are not present in any other known species of moradisaurine (densely ornamented maxillar teeth), and it is therefore described asBalearosaurus bombardensisgen. et sp. nov. Other remains found in the same outcrop are identified as cf.Balearosaurus bombardensisgen. et sp. nov., as they could also belong to the newly described taxon. This species is sister to the moradisaurine from the lower Permian of the neighbouring island of Mallorca, and is also closely related to the North American genusRothianiscus. This makes it possible to suggest the hypothesis that the Variscan mountains, which separated North America from southern Europe during the Permian, were not a very important palaeobiogeographical barrier to the dispersion of moradisaurines. In fact, mapping all moradisaurine occurrences known so far, it is shown that their distribution area encompassed both sides of the Variscan mountains, essentially being restricted to the arid belt of palaeoequatorial Pangaea, where they probably outcompeted other herbivorous clades until they died out in the late Permian.

Stromatoporoid sponges were very abundant during the middle Palaeozoic Era and are thought to disappear at the end of the Devonian Period in the Hangenberg Crisis. However, there are records of organisms with stromatoporoid-type structure in Carboniferous strata, the subject of this study. The Viséan fossil Labechia carbonaria Smith 1932 has been discussed previously in literature and its affinity has not been confirmed. In this study, the type material of L. carbonaria collected from the middle part of the Frizington Limestone Formation (previously called Seventh Limestone), Holkerian Substage, stored in the Natural History Museum (London, UK) and British Geological Survey (Keyworth, UK) was re-examined. The Holkerian Substage, in which L. carbonaria was found, lies between ca 335–339 Ma, and the Frizington Limestone Formation ranges from topmost Arundian to upper Holkerian, so middle Frizington Limestone Formation is likely approximately 337 Ma. L. carbonaria comprises thick long pillars connected by thin curved cyst plates consistent with the structure of the stromatoporoid genus Labechia. However, a common opinion is that L. carbonaria fossils may be mistaken for fragments of rugose corals, but there are problems with assigning it to the Rugosa. In vertical section (VS) L. carbonaria could be mistaken for a transverse section (TS) of a Carboniferous rugose coral. However, in TS L. carbonaria shows the rounded cross sections of stromatoporoid pillars. If it was a coral, septal sheets of the VS of a coral should be seen. For a rugose affinity to still apply, a coral structure would have to be composed of free trabeculae, but these are not known after the middle of the Devonian Period; there are no corals of Early Carboniferous age with the structure of L. carbonaria. Another interpretation, that L. carbonaria is a chaetetid, is discounted because it lacks calicles and is very different in structure from chaetetids. We conclude that L. carbonaria is a stromatoporoid. Because the beginning of the Carboniferous Period was ca 359 Ma, stromatoporoids thus occur approximately 22 million years after their purported disappearance at the end-Devonian Hangenberg Crisis. L. carbonaria, together with other rare occurrences in Carboniferous strata of stromatoporoid-form sponges Newellia mira (Newell) in USA, and uncertain taxa Komia Korde and Palaeoaplysina Krottow that have been attributed to stromatoporoids by some authors, supports some published views that end-Devonian stromatoporoid extinction may not have been as final as is traditionally interpreted. Thus Mesozoic stromatoporoids may represent resurgence of sponge lineages that survived the late Palaeozoic, perhaps in uncalcified form. Palaeogeographically, during the Early Carboniferous, the UK was positioned in low latitudes and in a central location of global distribution of reefal buildups during the late Palaeozoic continental assembly towards Pangaea. Thus it is curious that L. carbonaria is found in only one place; future search may determine its true palaeographic distribution, with potential reconsideration of the extinction of stromatoporoids at the end of the Devonian Period.

International audience; Jurassic flora of the Tibetan Plateau is poorly known, with limited fossil records. The paleobiogeography of terres- trial biota is, however, one of the major evidences to reconstruct the intricate paleogeography of an area. Well- preserved fossil wood is described from the Middle Jurassic Xiali Formation (Callovian) in the South Qiangtang terrane of the Tibetan Plateau, SW China. The wood specimen is a well-preserved secondary xylem without growth rings. Bordered pits on the radial tracheid walls are mostly uniseriate distant, locally contiguous. Cross- fields have 1–2 large oopores. A systematic study indicates that the current fossil wood represents a new species, Circoporoxylon tibetense sp. nov. This is the earliest Laurasian data for the genus Circoporoxylon, which has a Gondwanan origin and subsequently became common in Laurasia during the Cretaceous. The present new find- ing indicates that Circoporoxylon might have reached the Laurasia via a Tibetan terrane. The presence of fungal remains and wood rotting structures resembling the extant white-rot testifies for the plant–fungal interaction in the Callovian. The absence of growth rings in Circoporoxylon wood and the absence of gypsum layers in the South Qiangtang terrane, together with the widely occurrence of gypsum layers in the North Qiangtang terrane, suggests the South Qiangtang terrane might be wetter than the latter during the Callovian age. The paleogeomorphological highlands of Central Uplift were most likely the boundary between the two. This paleoclimate zonation implies that the Permian to Mesozoic megamonsoon of the supercontinent Pangaea might have terminated in the northern of Paleo-Tethys before the Callovian.

Fission-track analysis in zircon and apatite detrital grains from Mesoproterozoic sedimentary sequences show evidence of cooling episodes in central Brazil from Neoproterozoic to Cenozoic. Apatite fission-track ages reveal a main cooling episode during the Late Cretaceous-Early Paleogene, providing important clues on cooling by uplift and denudation during drifting of South America and Africa. Zircon data also suggest 3 distinct cooling events: (i) a Neoproterozoic-Cambrian event, probably related to orogenic exhumation of the Brasilia Belt and the thermal decay of West Gondwana assembly, (ii) a Devonian-Carboniferous event, probably related to the Late Famatinian orogeny and early stages of the Gondwanide orogeny, and (iii) an Early Permian to Triassic event, linked to the Late Gondwanide orogeny. These results indicate that the processes of assembly and breakup of supercontinents might significantly affect the plate interior, especially along with ancient orogenic belts. Zircon data has shown evidence of thermal decay during and after the West Gondwana assembly. Apatite data, on the other hand, has shown evidence of thermal decay during and after the breakup of Pangaea. The processes of assembly as well as the breakup of supercontinents can be tracked in the intracratonic setting, especially along with ancient orogenic belts. These assumptions take us back to the old concept of “mobile belts” as old orogenic regions that represent weak portions of the continental crust, assumed to have a greater tendency for mobility when solicited. In this case, the Brasilia Belt has shown to present great vertical mobility, accommodating tectonic far-field forces by uplift and as a result, feeding the Phanerozoic basins around it.

The Earth is currently 180 Myr into a supercontinent cycle that began with the break-up of Pangaea and which will end around 200–250 Myr (million years) in the future, as the next supercontinent forms. As the continents move around the planet they change the geometry of ocean basins, and thereby modify their resonant properties. In doing so, oceans move through tidal resonance, causing the global tides to be profoundly affected. Here, we use a dedicated and established global tidal model to simulate the evolution of tides during four future supercontinent scenarios. We show that the number of tidal resonances on Earth varies between one and five in a supercontinent cycle and that they last for no longer than 20 Myr. They occur in opening basins after about 140–180 Myr, an age equivalent to the present-day Atlantic Ocean, which is near resonance for the dominating semi-diurnal tide. They also occur when an ocean basin is closing, highlighting that within its lifetime, a large ocean basin – its history described by the Wilson cycle – may go through two resonances: one when opening and one when closing. The results further support the existence of a super-tidal cycle associated with the supercontinent cycle and gives a deep-time proxy for global tidal energetics.

The formation and subsequent breakup of the supercontinent Pangaea has dominated Earth’s evolution for the last 320 million years. Although its configuration at the time of breakup is widely accepted, there remains uncertainty about its configuration at the time of its amalgamation. The classic Pangaea-A model, widely known as “Wegenerian” configuration, implies that Pangaea did not deform internally between amalgamation and breakup. Palaeomagnetic studies suggest the possibility of a Pangaea-B configuration, in which Gondwana was located about 3000 km farther east relative to Laurasia compared its location in Pangaea-A. Here, we provide firm evidence of an Iberian-Appalachian connection in the Late Pennsylvanian (307–299 Ma) which confirms a Pangaea-A configuration for the relative locations of Gondwana and Laurasia in the late Palaeozoic, negating the possibility of Pangaea-B at that time. This evidence is based on palaeobotanical and biostratigraphic findings recently documented in the Carboniferous successions of Iberia (Douro Basin, Portugal). These new findings also precisely constrain the timing of uplift of the Appalachian and Iberian (Variscan) orogens and climatic changes during the amalgamation of Pangaea and final closure of the Rheic Ocean.

Pollen records from Siberia are mostly absent in global or Northern Hemisphere synthesis works. Here we present a taxonomically harmonized and temporally standardized pollen dataset that was synthesized using 173 palynological records from Siberia and adjacent areas (northeastern Asia, 42–75∘ N, 50–180∘ E). Pollen data were taxonomically harmonized, i.e. the original 437 taxa were assigned to 106 combined pollen taxa. Age–depth models for all records were revised by applying a constant Bayesian age–depth modelling routine. The pollen dataset is available as count data and percentage data in a table format (taxa vs. samples), with age information for each sample. The dataset has relatively few sites covering the last glacial period between 40 and 11.5 ka (calibrated thousands of years before 1950 CE) particularly from the central and western part of the study area. In the Holocene period, the dataset has many sites from most of the area, with the exception of the central part of Siberia. Of the 173 pollen records, 81 % of pollen counts were downloaded from open databases (GPD, EPD, PANGAEA) and 10 % were contributions by the original data gatherers, while a few were digitized from publications. Most of the pollen records originate from peatlands (48 %) and lake sediments (33 %). Most of the records (83 %) have ≥3 dates, allowing the establishment of reliable chronologies. The dataset can be used for various purposes, including pollen data mapping (example maps for Larix at selected time slices are shown) as well as quantitative climate and vegetation reconstructions. The datasets for pollen counts and pollen percentages are available at https://doi.org/10.1594/PANGAEA.898616 (Cao et al., 2019a), also including the site information, data source, original publication, dating data, and the plant functional type for each pollen taxa.

Unicellular dinophytes include a considerable number of harmful algae and potent producers of toxins. The dinophyte fossil record is one of the richest among protists and indicates a geologically old origin of the group dating back to the Triassic. Besides of these records, very few molecular dating studies of dinophytes have been published to date, precluding an understanding of the diversification history of these organisms. In the present study, we used first appearances in the fossil record for the best-represented dinophyte lineages, namely Gonyaulacales and Peridiniales, to calibrate a molecular phylogeny. It is inferred from ribosomal RNA sequence data covering a representative taxon sampling of all currently recognised lineages. Dinophytes may have started diversifying during main tectonic events of the supercontinent Pangaea, witnessing and surviving some of the biggest mass extinction events on Earth. Groups including harmful dinophytes originated at different points in time, but they all predate the Cretaceous–Paleogene boundary. Our chronogram provides a first time frame and may stimulate studies in future bringing molecular phylogenetics of dinophytes and their impressive fossil record together in more detail.

A supercontinent is generally considered to reflect the assembly of all, or most, of the Earth's continental lithosphere. Previous studies have used geological, atmospheric and biogenic ‘geomarkers’ to supplement supercontinent identification. However, there is no formal definition of how much continental material is required to be assembled, or indeed which geomarkers need to be present. Pannotia is a hypothesized landmass that existed in the interval c. 0.65–0.54 Ga and was comprised of Gondwana, Laurentia, Baltica and possibly Siberia. Although Pannotia was considerably smaller than Pangaea (and also fleeting in its existence), the presence of geomarkers in the geological record support its identification as a supercontinent. Using 3D mantle convection models, we simulate the evolution of the mantle in response to the convergence leading to amalgamation of Rodinia and Pangaea. We then compare this supercontinent ‘fingerprint’ to Pannotian activity. For the first time, we show that Pannotian continental convergence could have generated a mantle signature in keeping with that of a simulated supercontinent. As a result, we posit that any formal identification of a supercontinent must take into consideration the thermal evolution of the mantle associated with convergence leading to continental amalgamation, rather than simply the size of the connected continental landmass.

The Variscan orogeny occurred as a result of the Late Devonian to Late Carboniferous collision and accretion of Gondwana-derived microcontinents and continental masses with those of Laurussia. The irregular boundaries of the colliding continents caused isochronous transpressional and transtensional tectonics, accompanied by a complex pattern of intracontinental shear zones at the scale of the southern European Variscides. These shear zones and their configuration controlled the subsequent evolution of Permian to Middle Triassic paleogeography. The geographic distribution, from Morocco to the Eastern Alps, of the Late Carboniferous–Permian up to Triassic basins, most of which are considered as pull-apart basins, was related with the development of the Late Palaeozoic intracontinental shear network. Our analysis of the stratigraphic, tectonic and volcanic features of the Late Carboniferous/Permian continental basins across the Laurussia/Gondwana boundary reveals the role of the East Variscan Shear Zone during this time as a precursory lineament for the development of the Permian to Triassic rifting of Pangaea and the following opening of oceanic basins (e.g., the Neothetyan Ocean).

The breakup of Pangaea was accompanied by extensive, episodic, magmatic activity. Several Large Igneous Provinces (LIPs) formed, such as the Central Atlantic Magmatic Province (CAMP) and the North Atlantic Igneous Province (NAIP). Here, we review the chronology of Pangaea breakup and related large-scale magmatism. We review the Triassic formation of the Central Atlantic Ocean, the breakup between East and West Gondwana in the Middle Jurassic, the Early Cretaceous opening of the South Atlantic, the Cretaceous separation of India from Antarctica, and finally the formation of the North Atlantic in the Mesozoic-Cenozoic. We demonstrate that throughout the dispersal of Pangaea, major volcanism typically occurs distal from the locus of rift initiation and initial oceanic crust accretion. There is no location where extension propagates away from a newly formed LIP. Instead, LIPs are coincident with major lithosphere-scale shear movements, aborted rifts and splinters of continental crust rifted far out into the oceanic domain. These observations suggest that a fundamental reappraisal of the causes and consequences of breakup-related LIPs is in order.

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.

Between the end-Triassic mass extinction and the Toarcian Oceanic Anoxic Event, the Early Jurassic witnessed important changes in carbon burial, palaeogeography and paleoceanography, which were linked to the initial breakup of Pangaea. In order to better understand the climate and environmental impact of this phase of major tectonic rearrangement we revisited a key section along the Dorset coast (UK) and used a multi-proxy geochemical approach for its analysis. Carbon isotopes (δ13C) measured on organic matter were corrected for the influence of changes in the type of organic matter. The thus obtained δ13C-HI index and an additional δ13Ccarb record measured on bulk carbonate indicate a suite of carbon-isotope excursions (CIEs) including the negative main CIE (Triassic-Jurassic boundary to early Sinemurian) the negative Sinemurian-Pliensbachian boundary CIE and the positive margaritatus Zone (late Pliensbachian) CIE. Based on elevated hydrogen index values and enrichments in Mo, U, V, total organic carbon (TOC) and pyrite, the Hettangian-Sinemurian interval was interpreted to have been characterised by high productivity conditions and strong oxygen depletion of the basin. The chemical alteration index (CIA), clay mineralogy, and δ18O data provide independent evidence for increased continental runoff triggered by humid climate conditions on the adjacent continent during this time period. The strongest oxygen-depleted conditions were inferred for the lowermost Hettangian interval, coincident with the onset of the main negative CIE. A further less strongly oxygen-depleted interval was recorded through the negative CIE near the Sinemurian-Pliensbachian boundary (jamesoni and ibex Zones). This interval was characterised by drier conditions and possibly cooler water temperatures (e.g. CIA, δ18Ocarb and kaolinite/illite ratio). Based on low CIA values and kaolinite/illite ratios, the Pliensbachian climate is considered to have been generally drier, superimposed by more humid episodes restricted to the davoei and margaritatus Zones. The long-term trend to drier conditions is explained by: (1) diminished atmospheric CO2 contents due to a reduction in emissions of volcanogenic greenhouse gases, and/or; (2) changes in the palaeogeography and current patterns related to the break-up of Pangaea and more specifically to the opening of the Hispanic corridor.

Triassic orthogneisses of the Antarctic Peninsula provide evidence for the Palaeozoic and Mesozoic geological evolution of southern Gondwana within Pangaea. These rocks are sporadically exposed in southeastern Graham Land and northwestern Palmer Land, although reliable geochronological, geochemical and isotopic data are sparse. We combine new geochronological (LA-ICP-MS zircon U Pb), geochemical, and zircon (Hf, O) and whole rock isotopic (Nd, Sr and Pb) data to constrain the age and Triassic – Palaeozoic tectonic setting of these rocks. Zircon cores record Palaeozoic arc magmatism between 253 ± 2 and 528 ± 6 Ma, which was mainly located to the west of the Eastern Palmer Land Shear Zone (Central Domain; Vaughan and Storey, 2000 ). The arc is considered to be an extension of contemporaneous Palaeozoic arcs that have been identified along the Pacific margin of South America and the Thurston Island Block. Regions to the east of the Palmer Land Shear Zone (Eastern Domain, Vaughan and Storey, 2000 ) were located distal from the Terra Australis Margin, and possibly resided within Sunsas-aged belts within Pangaea. Triassic continental arc, calc-alkaline magmatism during 223–203 Ma modified the crust of the Antarctic Peninsula on both sides of the Eastern Palmer Land Shear Zone. Magmatic sources included igneous and sedimentary crustal material, which formed by crustal reworking during Sunsas- and Braziliano-aged orogenesis, and Palaeozoic arc magmatism. Arc magmatism accompanied sinistral extension which brought both domains into the arc and resulted in steady oceanward migration of the Triassic arc during the Middle – Late Triassic. We propose that sinistral displacement occurred along the Eastern Palmer Land Shear Zone, and this structure was active as early as the Triassic. Finally, we conclude that both the Eastern and Central Domains are autochthonous to Gondwana.

Fossil shells of benthos and nektobenthos have been shown to be faithful recorders of seawater carbon- and oxygen-isotope geochemistry, and thus also useful to track the relationship between carbon cycle and palaeotemperature. In this study we present an extensive dataset from Lower Jurassic (Hettangian and lower Sinemurian) mollusc and brachiopod hard parts collected from biostratigraphically well-calibrated UK coastal outcrops (Bristol Channel and Hebrides basins). These basins lay palaeogeographically in the southern part of the Laurasian Seaway that connected the Tethys and Boreal oceans. All samples have been subject to screening for diagenesis on the basis of elemental composition, light microscopy, and SEM observations. In the case of some localities within the Hebrides Basin, alteration by hydrothermal systems around Paleogene intrusions has led to re-setting of carbonate oxygen isotopes, but the original carbon isotope values from the shells are largely preserved. Above the prominent and apparently short-lived, ~3 per mil δ13Ccarb amplitude positive carbon-isotope excursion (CIE) that occurs immediately above the Triassic-Jurasic (T-J) boundary (in the tilmanni ammonite biozone), a pronounced negative CIE (the so-called Main Negative CIE) spans the entire Hettangian Stage. At the Hettangian-Sinemurian boundary, and through the lower Sinemurian, the carbon-isotope values of the skeletal carbonate again trend towards progressively more positive values, but representing a time of several million years. The heaviest δ13Ccarb values of about +4.3 per mil are evident towards the top of the lower Sinemurian, and are comparable with values observed from the tilmanni Zone, and from the lower Toarcian, higher in the Jurassic. This long-term positive hump, which confirms trends derived from bulk organic matter carbon-isotope records, is supporting evidence of prolonged enhanced organic carbon burial that is inferred to have occurred in the extensive system of lacustrine and marine rifts that traversed a fragmenting Pangaea after emplacement of the Central Atlantic Magmatic Province. In parallel, oxygen-isotope values of the skeletal carbonate show a continuous downward trend from the lower part of the Hettangian (~ −1 per mil δ18Ocarb in the planorbis Zone) to the top of the lower Sinemurian (~ −2.5 per mil δ18Ocarb in the higher turneri Zone). Oxygen-isotope values may be interpreted as due to gradually increasing palaeotemperature, and/or addition of a meteoric or cryospheric water component; in the case of the Laurasian Seaway, palaeoceanographic and palaeoecological considerations point towards a dominant palaeotemperature signal. Consequently, any atmospheric carbon-dioxide drawdown effect on global palaeotemperatures, as suggested by progressively increasing δ13Ccarb values, and assuming a constant silicate weathering sink, was more than counterbalanced in the seaway by regional processes that led to significantly warmer bottom water temperatures.

The Permian-Triassic mass extinction (PTME, ca. 252 Mya) was one of the most severe biotic crises of the Phanerozoic, eliminating >90% of marine and terrestrial species. This was followed by a long period of recovery in the Early and Middle Triassic which revolutionised the structure of both marine and terrestrial ecosystems, triggering the new ecosystem structure of the Mesozoic and Cenozoic. Entire new clades emerged after the mass extinction, including decapods and marine reptiles in the oceans and new tetrapods on land. In both marine and terrestrial ecosystems, the recovery is interpreted as stepwise and slow, from a combination of continuing environmental perturbations and complex multilevel interaction between species in the new environments as ecosystems reconstructed themselves. Here, we present a review of Early Triassic terrestrial tetrapod faunas, geological formations and outcrops around the world, and provide a semi-quantitative analysis of a data set of Early Triassic terrestrial tetrapods. We identify a marked regionalisation of Early Triassic terrestrial tetrapods, with faunas varying in both taxonomic composition and relative abundance according to palaeolatitudinal belt. We reject the alleged uniformity of faunas around Pangaea suggested in the literature as a result of the hot-house climate. In addition, we can restrict the “tetrapod gap” of terrestrial life in the Early Triassic to palaeolatitudes between 15°N and about 31°S, in contrast to the earlier suggestion of total absence of tetrapod taxa between 30°N and 40°S. There was fairly strong provincialism following the PTME, according to cluster analysis of a taxon presence matrix, entirely consistent with Early Triassic palaeobiogeography. Unexpectedly, the overall pattern for Early Triassic terrestrial tetrapod faunas largely reflects that of the Late Permian, suggesting that the recovery faunas in the Early Triassic retained some kind of imprint of tetrapod distributions according to palaeogeography and palaeoclimate, despite the near-total extinction of life through the PTME.

Compared to the other continents and lands, Antarctica suffers from a severe shortage of in situ observations of precipitation. APRES3 (Antarctic Precipitation, Remote Sensing from Surface and Space) is a program dedicated to improving the observation of Antarctic precipitation, both from the surface and from space, to assess climatologies and evaluate and ameliorate meteorological and climate models. A field measurement campaign was deployed at Dumont d'Urville station at the coast of Adélie Land in Antarctica, with an intensive observation period from November 2015 to February 2016 using X-band and K-band radars, a snow gauge, snowflake cameras and a disdrometer, followed by continuous radar monitoring through 2016 and beyond. Among other results, the observations show that a significant fraction of precipitation sublimates in a dry surface katabatic layer before it reaches and accumulates at the surface, a result derived from profiling radar measurements. While the bulk of the data analyses and scientific results are published in specialized journals, this paper provides a compact description of the dataset now archived in the PANGAEA data repository (https://www.pangaea.de, https://doi.org/10.1594/PANGAEA.883562) and made open to the scientific community to further its exploitation for Antarctic meteorology and climate research purposes.

The Eastern Siberian Arctic Shelf (ESAS) represents a geologically complex realm with a tectonic history that is related to the final stages of the formation of the Pangaea supercontinent during the Mesozoic and its subsequent disintegration during the Late Cretaceous and Cenozoic. It is a key region to constrain the origin of the deep-water basins and intervening ridges of the Amerasia Basin. We present results of gravity modeling of published seismic refraction and reflection profiles acquired between 1989 and 2012 over the ESAS and adjacent Arctic Ocean along five composite geotransects using Getech’s satellite altimeter-derived gravity data. Our main goal was to examine published crustal models and to present new models for the ESAS that are constrained by both seismic data and 2D gravity forward modeling. We consider several topics important for understanding Arctic geology: (i) hyperextension within the Laptev Rift System and the possible extent of the exhumed mantle, (ii) the relationship between the New Siberian Shelf and the Lomonosov Ridge, (iii) the nature of the collapsed upper Mesozoic fold belt in the southern part of the East Siberian Sea, (iv) the character of transition between the De Long Massif and the deep-water Podvodnikov Basin, (v) the lateral extent of the hyperextended North Chukchi Basin and the nature of its basement, and (vi) relationship between the Mendeleev Ridge and Chukchi Plateau crustal domains. Our results do not confirm the previously inferred extent of continental crust beneath the oceanic realm. The latter is dominated by High Arctic Large Igneous Province (HALIP) igneous crust. We discuss the existence of a dismembered continental Bennett-Barrovia block that is currently represented by three smaller fragments/massifs. When restored to its possible single state, this block can play a crucial role in reconstructing the pre-Canada Basin Arctic.

18 pages, 7 figures, supporting information https://doi.org/10.1029/2019TC005586.-- Data are available at the PANGAEA world data center https://doi.org/10.1594/PANGAEA.909047, We present a 2‐D P wave velocity model and a coincident multichannel seismic reflection profile characterizing the structure of the southern Costa Rica margin and incoming Cocos Ridge. The seismic profiles image the ocean and overriding plates from the trench across the entire offshore margin, including the structures involved in the 2002 Osa earthquake. The overriding plate consists of three domains: Domain I displays thin‐skinned deformation of an imbricate thrust system composed of fractured rocks. Domain II shows ~15‐km‐long landward dipping reflection packages and active deformation of the shelf sediment. Domain III is little fractured and appears to be dominated by elastic deformation, overlain by ~2‐km‐thick landward dipping strata. The velocity structure supports the argument that the bulk of the margin is highly consolidated rock. Thick‐skinned tectonics probably causes the uplift of Domains II and III. The oceanic plate shows crustal thickness variations from ~14 km at the trench (Cocos Ridge) to 6–7 km beneath the shelf. We combine (1) interplate geometry and fracturing degree, (2) tectonic stresses and brittle strain, and (3) earthquake locations, to investigate relationships between structure and earthquake generation. The 2002 Osa sequence nucleated at the leading flank of subducting seamounts in the area of highest tectonic overpressure. Both estimated rock fracturing and modeled brittle strain steadily increase from the leading flank of the subducting seamounts to their top, reflecting the progressive damage caused by the seamount. Therefore, the seismicity and structural‐mechanical evolution of the upper plate reflect the downward propagation of the leading edge of seamounts, This research was supported by E‐FIRE (PCIN‐2015‐053) and FRAME (CTM2015‐71766‐R) projects, as well as the People Programme (Marie Curie Actions) under REA Grant Agreement 604713 (ZIP “Zooming In between Plates”)