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Tephra layers of the Mýtina Maar, Czech Republic, contain ferrimagnetic Mg–Al-rich titanomagnetite, which is suggested to originate from a fractionated alkaline CO2-rich lithospheric mantle melt. We investigated the magnetic mineralogy and Curie temperature (TC) from tephra deposits of two drill cores (, Deutsche Forschungsgemeinschaft http://dx.doi.org/10.13039/501100001659, CzechGeo/EPOS

International audience; The southern part of Madagascar consists of a granulitic metamorphic belt with a complex Proterozoic shear zone network. Aeromagnetic maps reveal sharp magnetic spatial gradients, especially across shear zones. All shear zones are associated with high magnetic values, except one, the Beraketa shear zone. Based upon relationships between rock magnetic properties, petrographic and aeromagnetic data, we show that the magnetic signal is controlled by variations in proportions of iron-rich oxides. Their nature and texture are variable and complex. Magnetite and ilmenite are often observed together showing intergrowths texture, suggesting possible lamellar magnetism. Detailed petrographic observations of the Zazafotsy shear zone show that a strong magnetic signal is correlated with metamorphic reactions and especially with biotite breakdown to peritectic phases such as orthopyroxene and iron-rich oxides (metamorphic charnockitization). Magmatic material can migrate easily inside the Zazafotsy shear zone and inside the fold hinges close to the shear zone, increasing the kinetics of charnockitic reaction. In opposition, inside the Beraketa shear zone, lower magnetic values are correlated with the absence of iron-rich oxides. This is interpreted as back reaction melting. Thus, peritectic phases, such as iron-rich oxides, react with the water released when magmas crystallise to produce biotite. Inside the Zazafotsy shear zone, iron-rich oxides are stable because part of the migmatite was segregated and escaped with dissolve H2O. In this case, back reaction was no longer possible.

International audience; Results of a statistical study of equatorial noise emissions are presented. These electromagnetic emissions are observed in the inner magnetosphere in the vicinity of the geomagnetic equator at frequencies below the lower hybrid frequency. We use the data recorded by four Cluster spacecraft during years 2001-2003. The data set was processed in three steps. In the first one, we have selected the data with a nearly linear polarization (ellipticity less than 0.2), corresponding to the known properties of the equatorial noise. Secondly, we have found parameters of a Gaussian model of the frequency-averaged power-spectral density of those selected waves as a function of the geomagnetic latitude. Finally, we have analyzed the data in the latitudinal interval defined by the width of the Gaussian model. Our results show that most intensity peaks of equatorial noise occur exactly at the magnetic equator. Incidental deviations are most probably caused by problems in determination of the true magnetic equator, which is shown by using different magnetic field models. We have estimated the plasma number density at the observation points using the cold plasma theory. These estimates are, within experimental errors, close to the values obtained from the spacecraft potential data measured by the EFW instrument.

Observations of proton density fluctuations of the solar wind at 1 au have shown the presence of a decade-long transition region of the density spectrum above sub-ion scales, characterized by a flattening of the spectral slope. We use the proton density fluctuations data collected by the BMSW instrument on-board the Spektr-R satellite in order to delimit the plasma parameters under which the transition region can be observed. Under similar plasma conditions to those in observations, we carry out 3D compressible magnetohydrodynamics (MHD) and Hall-MHD numerical simulations and find that Hall physics is necessary to generate the transition region. The analysis of the kω power spectrum in the Hall-MHD simulation indicates that the flattening of the density spectrum is associated with fluctuations having frequencies smaller than the ion cyclotron frequency.

The non-cylindrical character of the Variscan Belt is established via a description of its most salient geological characteristics and correlations among the main and relatively minor massifs from Bohemia to Morocco on the basis of a bibliographical synthesis. Using the firmly established tectonostratigraphic domains, the continuity of Variscan zones is discussed, as well as the western termination of the one that occupies most of the central part of the belt. This zone is characterized by its allochthony, and breaks the continuity of the zonation, that is, the cylindrism of the belt. A proposal is made to call this zone the Mid-Variscan Allochthon and its wedge shape in map view is explained performing a step by step restoration of late Variscan deformation. Once the geometry of the belt is interpreted by a succession of regionally significant deformation events, a kinematic reconstruction is proposed. It is based on recent developments on the knowledge of Paleozoic plate tectonics and intended to show that the deformation model is compatible with current paleogeographical developments.

International audience; BepiColombo Mio (previously called MMO: Mercury Magnetospheric Orbiter) was successfully launched by Ariane 5 from Kourou, French Guiana on October 20, 2018. The Mercury Plasma/Particle Experiment (MPPE) is a comprehensive instrument package onboard Mio spacecraft used for plasma, high-energy particle and energetic neutral atom measurements. It consists of seven sensors including two Mercury Electron Analyzers (MEA1 and MEA2), Mercury Ion Analyzer (MIA), Mass Spectrum Analyzer (MSA), High Energy Particle instrument for electron (HEP-ele), High Energy Particle instrument for ion (HEP-ion), and Energetic Neutrals Analyzer (ENA). Significant efforts were made pre-flight to calibrate all of the MPPE sensors at the appropriate facilities on the ground. High voltage commissioning of MPPE analyzers was successfully performed between June and August 2019 and in February 2020 following the completion of the low voltage commissioning in November 2018. Although all of the MPPE analyzers are now ready to begin observation, the full service performance has been delayed until Mio’s arrival at Mercury. Most of the fields of view (FOVs) of the MPPE analyzers are blocked by the thermal shield surrounding the Mio spacecraft during the cruising phase. Together with other instruments on Mio including Magnetic Field Investigation (MGF) and Plasma Wave Investigation (PWI) that measure plasma field parameters, MPPE will contribute to the comprehensive understanding of the plasma environment around Mercury when BepiColombo/Mio begins observation after arriving at the planet Mercury in December 2025.

International audience; Very low frequency wave intensity measurements provided by the French low‐altitude DEMETER spacecraft are studied using the principal component analysis (PCA). We focus on both the physical interpretation of the first two principal components and their application to real physical problems. Variations of the first principal component (PC1) coefficients due to the geomagnetic activity and seasonal/longitudinal changes are studied. It is shown that their distribution corresponds to the wave intensity dependences obtained in previous studies. Moreover, the variations of PC1 coefficients around interplanetary shock arrivals are analyzed. The study is performed for fast forward (FF), fast reverse, slow forward, and slow reverse shocks separately. It shows that the most significant effect on the wave intensity is displayed in the FF case. Furthermore, it turns out that the wave intensity variations depend on the wave intensity detected before the shock arrival. Finally, the shock strength and interplanetary magnetic field orientation are also important. The performed analysis shows that PCA can be successfully applied to characterize large data sets of spacecraft measurements by limited sets of numbers—principal component coefficients (typically first one or two are enough), which still maintain a sufficient amount of information.

International audience; A multidisciplinary approach integrating potential field analysis with geological and geochemical data provides new insights into the understanding of the crustal structure and evolution of the Mongolian collage. Magnetic and gravity data demonstrate the inconsistency between the geologically defined terranes and the geophysical domains in the southwestern part of the Mongolian collage. The combination of potential field analysis and modelling with whole rock geochemistry and isotopic mapping of Carboniferous–Permian granitoids indicates the presence of a homogeneous lower crust composed of a felsic to intermediate juvenile material beneath geophysically heterogeneous upper crust. This feature is interpreted as a result of a trench-directed lower crustal emplacement of an arc type crust underplating deformed Paleozoic oceanic crust. The potential field data also confirmed the occurrence of two orthogonal late Devonian and Permian–Triassic deformation upper crustal fabrics at the scale of the southwestern Mongolian collage. The prominent magnetic highs correspond to the tectono-metamorphic domains and magmatic provinces. The gravity anomalies highlight a periodicity of the signal correlating with alternating Permian–Triassic high and low strain zones, forming a zone of major deformation wrapping around the hinge of Mongolian orocline. The geometry and kinematics of dextral and sinistral transpressive faults are explained to result from the reactivation of Permian–Triassic deformation zones in the Cenozoic stress field.

International audience; Jupiter's icy moon Europa harbors underneath tectonically modified ice shell (Figueredo & Greeley, 2004; Kattenhorn & Prockter, 2014) a salty ocean (Kivelson et al., 2000) in direct contact with a rocky interior that may still be active (Moore & Hussmann, 2009). Such an oceanic environment makes Europa a primary target in the search for a habitable world beyond Earth (Hand et al., 2009). The chemical evolution of Europa's ocean and its habitability is conditioned by the interaction with the rocky seafloor (Vance et al., 2016). It depends on the heat released from the deep interior to the seafloor (Altair et al., 2018), and hence by the intensity of magmatic activity. BĚHOUNKOVÁ ET AL.

International audience; We present a new analogue model of oroclinal buckling, which is based on recent advances in our geological understanding of the Mongolian orocline in the Central Asian Orogenic Belt. The model simulates an amplification of a preexisting, gently arcuated accretionary system. In the analogue models, we established three neighboring subdomains that represent contrasting lithospheric domains separated by a steep “subduction” interface. The shortening of the model is parallel to the pseudo-linear interface between these subdomains and produces two different deformation patterns in the amplified interlimb areas of the orocline. We used analogue modelling techniques to investigate both the flow of a ductile lithosphere and the brittle deformation of an upper crust that is associated with the development of an orocline. The modelling results show that: (1) two types of regional-scale folds develop both of which are upright. The largest are steeply plunging oroclines and the smaller have sub-horizontal axes; (2) the overall deformation distribution displays significant thickening/thinning and exhumation of the lower ductile layers with variations of upward transfer of crustal material; (3) the hinge regions of the two adjacent oroclines studied consist of different materials, one contains oceanic and the other felsic lower crustal rocks. It is found that the geometry of the lithosphere beneath the two regions is very different; (4) the geometry of the orocline is non-cylindrical and exhibits an increasing plunge of fold axes when traced from the upper-crust to deeper lithospheric layers. The resulting model is used to geophysically constrain deep crustal structures and surface deformation patterns in Mongolia.

International audience; Electromagnetic waves observed in the inner magnetosphere at frequencies between about 0.5 and 4 kHz sometimes exhibit a quasiperiodic (QP) time modulation of the wave intensity with modulation periods from tens of seconds up to a few minutes. Such waves are typically termed QP emissions and their origin is still not fully understood. We use a large set of more than 2,000 of these events identified in the low-altitude DEMETER spacecraft data to check for energetic electron flux variations matching the individual QP wave elements. Altogether, 7 such events are identified and their detailed analysis is performed. Energetic electron fluxes are found to be modulated primarily at energies lower than about 250 keV. While the waves may propagate unducted across L-shells, the energetic particles follow magnetic field lines from the interaction region down to the observation point. This is used to estimate the locations of anticipated generation regions to L-shells between about 4 and 6, and the respective source radial dimensions to about 0.6-1.2 Earth radii. The frequencies of the events are confined below half of the equatorial electron gyrofrequency in the determined source regions. Finally, it is shown that individual QP elements exhibit a fine inner structure corresponding to the wave bouncing between the hemispheres.

The reaction of oxygen anions with carbon dioxide molecules is considered to be the main channel of CO3− ion formation in the Martian ionosphere. Comprehensive theoretical ion-chemical models of the Martian ionosphere require experimental data on the reactivity of negative ions with neutral gases under relevant ambient temperature and pressure conditions. The temperature dependence of the rate of the ternary reaction of O− with CO2 has been measured at temperatures relevant to the ionosphere of Mars using a VT-SIFT instrument using both helium and nitrogen as the carrier (ternary) gases. The ternary rate coefficient of the reaction was measured equal to (1.24 ± 0.06) × 10−28 (300/T)2.86±0.28 and (2.29 ± 0.05) × 10−28 (300/T)2.06±0.13 cm6s−1 for He and N2 carrier gas, respectively, in the temperature range of 230–340 K. The k3 is over two times higher in nitrogen than in helium and has a less strong inverse temperature dependence.

In response to ESA Voyage 2050 announcement of opportunity, we propose an ambitious L-class mission to explore one of the most exciting bodies in the Solar System, Saturn largest moon Titan. Titan, a "world with two oceans", is an organic-rich body with interior-surface-atmosphere interactions that are comparable in complexity to the Earth. Titan is also one of the few places in the Solar System with habitability potential. Titan remarkable nature was only partly revealed by the Cassini-Huygens mission and still holds mysteries requiring a complete exploration using a variety of vehicles and instruments. The proposed mission concept POSEIDON (Titan POlar Scout/orbitEr and In situ lake lander DrONe explorer) would perform joint orbital and in situ investigations of Titan. It is designed to build on and exceed the scope and scientific/technological accomplishments of Cassini-Huygens, exploring Titan in ways that were not previously possible, in particular through full close-up and in situ coverage over long periods of time. In the proposed mission architecture, POSEIDON consists of two major elements: a spacecraft with a large set of instruments that would orbit Titan, preferably in a low-eccentricity polar orbit, and a suite of in situ investigation components, i.e. a lake lander, a "heavy" drone (possibly amphibious) and/or a fleet of mini-drones, dedicated to the exploration of the polar regions. The ideal arrival time at Titan would be slightly before the next northern Spring equinox (2039), as equinoxes are the most active periods to monitor still largely unknown atmospheric and surface seasonal changes. The exploration of Titan northern latitudes with an orbiter and in situ element(s) would be highly complementary with the upcoming NASA New Frontiers Dragonfly mission that will provide in situ exploration of Titan equatorial regions in the mid-2030s., Comment: arXiv admin note: substantial text overlap with arXiv:1908.01374

Io, the innermost of Jupiter’s satellites, is the most volcanically active, and probably one of the most remarkable body in the outer Solar System [1]. The total power emitted from Io's surface is estimated to about 100 TW at present [2,3], which is several orders of magnitude greater than can be explained by radiogenic heating alone. Io’s interior process manifests on the surface as extreme volcanic activity, providing some clues about the thermal state of its interior through the eruption properties and global distribution of volcanism [e.g. 4,5]. A variety of models have been proposed to determine the mechanism at the origin of the huge tidal dissipation in Io’s interior [e.g. 6,7,8,9]. The presence of a partially molten layer in the upper mantle of Io is broadly consistent with these interior models prediction, as well as with magnetic induction measurements [10], although this interpretation has recently been questioned [11]. However, while a high concentration of melts below the lithosphere is in line to explain the heat production and the heat released by volcanic activity, the degree of melting of this subsurface layer, going from moderately molten mantle to fully liquid subsurface ocean [7], is still largely debated. The distribution of melt within Io is a key question driving future mission concept dedicated to Io’s investigation (IVO), planning to test these interior models via a set of geophysical measurements. One way to characterize it is through the tides. The measurement of the tidal deformation (either via the potential Love number k2 or the phase lag) can provide information about the internal structure of planetary bodies [e.g. 12]. The total amount of heat produced by tidal friction and its distribution in the interior is intimately linked to the structure and thermal state of Io's interior, especially the distribution of temperature and melt fraction [8,9]. Describing the mechanical response of partially molten rocks on a wide range of melt fraction is essential to correctly describe the tidal friction in Io, partial melt severely affecting viscoelastic properties of rocks. Understanding the retroaction between melt distribution and heat production is thus crucial to explain the heat budget of Io and to understand its tidally-induced volcanism. In this context, the goal of the study is to calculate the tidal response of Io’s interior [13] for various distribution of melt within the mantle, to discriminate them in future tidal monitoring. A coherent melt profile between the sublithospheric partially molten layer and the underlying mantle is considered following petrological and two-phase flow arguments [4,14]. A rheological parameterization is developed in order to take into account the role of melt fraction on the elastic and viscous parameters of Io's partially molten interior. The results are analyzed in terms of tidal Love number k2, taking into account a re-evaluation of the heat production by tidal friction in Io's partially molten interiors, by quantifying the role of melt fraction on both shear and bulk dissipation. Our calculations show that the amount of melt fraction within the 100-km thick asthenospheric partially molten layer could be discriminated from tidal k2 measurements and heat flow patterns. Depending on the assumed value of viscosity at the melting point and extent of melting beneath the lithosphere, three groups of internal structure models able to reproduce Io’s heat budget of 100 TW can be distinguished : (1) low viscosity mantle (17 Pa s) and moderately molten mantle and asthenosphere (1018 Pa s) with high melt content in the asthenosphere (>30%) ; (3) fully liquid magma ocean beneath a highly dissipative crust. Both mantle dissipation (1) and crust dissipation (2) models result in a comparable heat flow pattern, with maximal dissipation at the poles but can be distinguished by k2 measurements. The asthenospheric dissipation (2) model has a k2 Love number only slightly higher than the mantle dissipation model, but results in a totally different heat flow pattern. Note that our computed dissipation included bulk dissipation in addition to shear dissipation, which further enhances dissipation in the equatorial region for the asthenospheric dissipation (2) model. For the two other dissipation model, bulk dissipation has a negligible effect. Acknowledgements The present work received financial supports from the ANR OASIS project and from CNES (Europa Clipper/SUDA, JUICE). References [1] Lopes, R. M., and Williams, D. A., Io after Galileo. Reports on Progress in Physics, 68(2), 303 (2005).[2] Veeder, G. et al., JGR: Planets, Vol. 99, pp. 17095-17162 (1994).[3] Spencer, J. et al., Eos Trans AGU, Vol. 81, pp. 19 (2000).[4] Keszthelyi, L., Jaeger, W., Milazzo, M., et al. 2007, Icarus, 192, 491[5] Davies, A. G., G. J. Veeder, D. L. Matson, and T. V. Johnson (2015), Icarus, 262, 67–78[6] Segatz, M. et al., Icarus, Vol. 75, pp 187-206 (1988).[7] Tyler, R. H., W. G. Henning, and C. W. Hamilton (2015), Astrophys. J. Suppl. Ser., 218(2), 22.[8] Bierson, CJ. and Nimmo, F., JGR: Planets, Vol. 121, pp 2211-2224 (2016).[9] Steinke, T., Hu, H., Höning, D., van der Wal, W., & Vermeersen, B. 2020, Icarus,335, 113299[10] Khurana, K. et al., Science, Vol. 332, pp. 1186-1189 (2011).[11] Roth, L., Saur, J., Retherford, K. D., et al. 2017, Journal of Geophysical Research: Space Physics, 122, 1903[12] Dumoulin, C. et al., JGR : Planets, Vol. 122, pp. 1338 1352 (2017)[13] Tobie, G. et al., Icarus, Vol. 177, pp. 534-549 (2005).[14] Spencer, D. C., Katz, R. F., & Hewitt, I. J. 2020, arXiv preprint arXiv:2003.08287[15] de Kleer, K., Park, R., McEwen, A.S. Tidal heating: Lessons from Io and the Jovian System Final report (2019)

The Barrovian inverted metamorphism of the Svratka dome developed within two nappes derived from the Brunia continent that was thrust beneath the Moldanubian orogenic root. The metamorphism increases from biotite–chlorite zone in the basement to very closely spaced staurolite, kyanite and sillimanite zones at the top of the nappe pile. The sequence of mineral growth, chemical zoning of garnet, and pseudosection modelling indicate prograde paths from 4.5 kbar/510 °C to 5.5 kbar/540 °C in the garnet zone, from 6 kbar/530 °C to 7 kbar/600 °C in the staurolite zone, and from 3.5 kbar/510 °C to 8.5 kbar/650 °C in the kyanite zone. The age of monazite inclusions in garnet and staurolite is interpreted to reflect prograde metamorphism at 338 ± 7 Ma and 336 ± 7 Ma, respectively. An older matrix monazite crystal is interpreted as dating prograde crystallization at 345 ± 7 Ma, whereas a younger monazite group records recrystallization at/or down to 334 ± 7 Ma. While these petrological and geochronological data are consistent with data from an inverted metamorphic sequence of the southern Thaya dome, the spacing and distribution of metamorphic zones, nappe thicknesses, and late structures are different in the two domes. An antiformal stack of imbricated basement sheets and the extreme attenuation of metamorphic isograds at the top of the nappe pile in the Svratka dome are explained by a relatively cold overthrusting Moldanubian domain, formed mainly of middle orogenic crust. The homogeneous thickening of the hinterland-dipping basement duplexes and the regular spacing of metamorphic isograds in the Thaya dome are explained by a hot overriding Moldanubian domain, which in this region has a high proportion of exhumed lower orogenic crust and formed a hot mid-crustal channel.

High-pressure granitic orthogneiss of the south-eastern Orlica-Śnieżnik Dome (NE Bohemian Massif) shows relics of a shallow-dipping S1 foliation, reworked by upright F2 folds and a mostly pervasive N-S trending subvertical axial planar S2 foliation. Based on macroscopic observations, a gradual transition perpendicular to the subvertical S2 foliation from banded to schlieren and nebulitic orthogneiss was distinguished. All rock types comprise plagioclase, K-feldspar, quartz, white mica, biotite and garnet. The transition is characterized by increasing presence of interstitial phases along like-like grain boundaries and by progressive replacement of recrystallized K-feldspar grains by fine-grained myrmekite. These textural changes are characteristic for syn-deformational grain-scale melt percolation, which is in line with the observed enrichment of the rocks in incompatible elements such as REEs, Ba, Sr, and K, suggesting open-system behaviour with melt passing through the rocks. The P-T path deduced from the thermodynamic modelling indicates decompression from ~15−16 kbar and ~650-740 ºC to ~6 kbar and ~640 ºC. Melt was already present at the P-T peak conditions as indicated by the albitic composition of plagioclase in films, interstitial grains and in myrmekite. The variably re-equilibrated garnet suggests that melt content may have varied along the decompression path, involving successively both melt gain and loss. The 6-8 km wide zone of vertical foliation and migmatite textural gradients is interpreted as vertical crustal-scale channel where the grain-scale melt percolation was associated with horizontal shortening and vertical flow of partially molten crustal wedge en masse.

The Kutna Hora crystalline complex (KHCC) in the Bohemian Massif is a HP/HT complex adjacent to the magmatic arc. It is dominated by migmatite, orthogneiss and granulite with bodies of eclogite and peridotite. The KHCC migmatite consists of K-feldspar, plagioclase, quartz, phengite, biotite, garnet and kyanite. Melting conditions were estimated at 780 °C and >16 kbar and inferred melt volume varies between 1 and 4 vol%. Peak temperature is 865 °C at 18–19 kbar followed by decompression in the presence of melt to 12–13 kbar and 770–800 °C. U-Pb monazite geochronology reveals a spread of ages between 550 Ma and 330 Ma. REE patterns show low Yb/Gd for 550–500 Ma, high Yb/Gd for ages at ~480 Ma, and decreasing Yb/Gd towards ~340 Ma. First monazite in equilibrium with garnet constrains the HP metamorphism to ~350 Ma, which is followed by recrystallization of monazite down to 325 Ma. U-Pb zircon geochronology displays an age range from ~670 Ma to ~430 Ma. The broad age range records a span of protolith crystallization and/or old metamorphism. The presence of HP ky + mu migmatite, their P–T path, protolith zircon and monazite metamorphic ages and whole-rock geochemistry are similar to HP migmatites in the Eger crystalline complex (ECC) in the Saxothuringian domain further in the west. We propose the following geodynamic scenario for subduction-relamination-exhumation mechanism: (i) subduction of the Saxothuringian continental lithosphere at 360 Ma related to early stage of trans-lithospheric diapirism triggered by arc-related magma weakening; (ii) large-scale emplacement of relaminant into the upper plate lithosphere at 350–340 Ma; and (iii) return flow of the relaminant along the subduction interface (the ECC) and emplacement of relaminant in the upper–middle crust in the rear part of the arc system (the KHCC) at 340–330 Ma.

International audience; Quasiperiodic emissions are magnetospheric whistler mode waves at frequencies between about 0.5 and 4 kHz which exhibit a nearly periodic time modulation of the wave intensity. We use large data sets of events observed by the Van Allen Probes in the equatorial region at larger radial distances and by the low-altitude DEMETER spacecraft. While Van Allen Probes observe the events at all local times and longitudes, DEMETER observations are limited nearly exclusively to the daytime and significantly less frequent at the longitudes of the South Atlantic Anomaly. Further, while the events observed by Van Allen Probes are smoothly distributed over seasons with only mild maxima in spring/autumn, DEMETER occurrence rate has a single pronounced minimum in July. The apparent inconsistency is explained by considering a nondipolar Earth's magnetic field and significant background wave intensities which in these cases prevent the quasiperiodic events from being identified in DEMETER data.

A combined U–Pb zircon geochronological and whole-rock isotopic and geochemical study has been carried out on high-grade orthogneiss, meta-basite, and meta-sediments from the Erzgebirge. The results indicate multiple pulses of Ediacaran–Ordovician magmatism in a transitional volcanic-arc to rift-basin setting. Orthogneiss from high-pressure nappes exhibit a step-like pattern of inherited zircon ages and emplacement ages of 500–475 Ma. In contrast, granite gneiss from the medium-pressure core of the Erzgebirge is characterised by three pulses of magmatism in the Early Cambrian, Late Cambrian, and Early Ordovician. A trend of decreasing Th/U ratios in zircon is observed to c.500 Ma, after which significant increases in the trend and variability of the data is inferred to mark the transition from arc-related to rift-related magmatism. Sediments deposited in the Early Cambrian have continental island arc affinity. Major detrital peaks in the Ediacaran and subordinate Tonian, Palaeoproterozoic, and Neoarchaean data are consistent with an Avalonian-Cadomian Arc and West African Craton derivation. The Early Cambrian sediments were locally reworked by a thermal event in the Ordovician resulting in leucocratic banding and recorded in Ordovician zircon rims characterised by systematically lower Th/U ratios. Ptygmatically folded leucocratic bands containing Ordovician zircon rims, associated with low Th/U ratios, are further observed in the granite gneiss core of the Erzgebirge. Variscan ages are rare, except in a fine-grained high-pressure micaschist, which contains exclusively small, structure-less, zircon with a weighted mean age of 350 ± 2 Ma. These data, along with a re-evaluation of previously published data, have been interpreted as the product of flattening subduction during the Early Cambrian; followed by the opening of slab windows in the Late Cambrian; and finally delamination in the Early Ordovician. Delamination of the orphaned slab led to asthenospheric upwellings triggering extension, bimodal magmatic pulses, recycling of fertile crust, high-temperature metamorphism, and cratonisation of relatively young crust.

Tectonic evolution of the Paleoproterozoic Vaasa migmatitic complex (VMC) in the central part of the Svecofennian accretionary orogen is deciphered using aeromagnetic and gravity maps, deep seismic and magnetotelluric profiles, and structural and metamorphic data. The VMC is a semicircular structure with migmatitic rim and granitic core composed of several subdomes. It evolved in three main tectonic events (D1-D3). The D1 event (ca. 1.89-1.88 Ga) corresponds to the stacking of supracrustal rocks and the formation of an inverted metamorphic gradient. Anatexis at LP-HT metamorphic conditions enabled the material to flow. The D2 event (ca. 1.88-1.87 Ga) corresponds to large-scale folding of the partially molten crust within an orocline. It is marked by folds with an E-W vertical axial planar foliation. The late D3 event resulted from mass redistribution owing to mechanical instabilities within the hinge of the orocline. It is marked by vertical shearing (ca. 1.87-1.85 Ga) in the marginal parts of the complex and along the granitoid subdomes. The seismic reflection profile (FIRE 3a) and magnetotelluric profiles (MT-PE and MT-B2) image large-scale D1 stacking structures within an accretionary prism. Near vertical breaks in crustal-scale reflectivity and conductivity models are interpreted as D3 shear zones. The VMC is an example of early mass and heat transfer within a collage of hot supracrustal rocks in an accretionary belt. Partial melting enhanced the flow of material, the production, and rise of magma as well as exhumation, marked by magmatic domes in the hinge of the orocline.

International audience; The timing and mechanism of formation of the Tibet Plateau remain elusive, and even the present-day structure of the Tibetan lithosphere is hardly resolved, due to conflicting interpretations of the geophysical data. We show here that significant advances in our understanding of this orogeny could be achieved through a better assessment of the composition and rheological properties of the deepest parts of the Tibetan lithosphere, leading in particular to a reinterpretation of the global tomographic cross sections. We report mantle phlogopite xenocrysts and carbonate-bearing ultramafic cumulates preserved in Eocene potassic rocks from the Eastern Qiangtang terrane, which provide evidence that the lithospheric mantle in Central Tibet was enriched in H 2 O and CO 2 prior to the India-Asia collision. Rheological calculations and numerical modeling suggest that (1) such metasomatized mantle would have been significantly weaker than a normal mantle but buoyant enough to prevent its sinking into the deep mantle; (2) the slow seismic anomalies beneath Central Tibet may image a weakened lithosphere of normal thickness rather than a lithosphere thinned and heated by the convective removal of its lower part; and (3) melting of such soft and fusible metasomatized mantle would have been possible during intracontinental subduction, supporting a subduction origin for the studied Eocene potassic magmatism. These results demonstrate that the inheritance a soft and buoyant precollisional Tibetan lithosphere may have conditioned the growth and the present-day structure of the Tibet Plateau. Plain Language Summary The Tibetan Plateau is the largest relief on the Earth's surface, but also one of the least understood geodynamic phenomena, due to the lack of constrain on its growth evolution and mechanism. Here we have discovered, enclosed in Eocene (35-Ma-old) lavas from Central Tibet, hydrous and carbonated minerals derived from the underlying upper mantle, which reveal an unsuspected abundance of water and CO 2 in this upper mantle. We show that, consequently, the upper mantle beneath Central Tibet has been anomalously weak since before the collision of India with Asia. It was previously thought to have disappeared, foundered in a process called "delamination," but we demonstrate here that this was an artifact: Most of the tibetan mantle is still there, but it is very weak and therefore does not appear on the seismic images. This implies that models expecting the Tibet Plateau to be a result of a delam-ination process are probably wrong; instead, we propose a model in which the weak upper mantle beneath our study area was easily indented by the strong adjacent continental block; this model manages to explain both Eocene magmatism and uplift in our study area.

Pressures in the hydrospheres of large ocean worlds extend to ranges exceeding those in Earth deepest oceans. In this regime, dense water ices and other high-pressure phases become thermodynamically stable and can influence planetary processes at a global scale. The presence of high-pressure ices sets large icy worlds apart from other smaller water-rich worlds and complicates their study. Here we provide an overview of the unique physical states, thermodynamics, dynamic regimes, and evolution scenarios specific to large ocean worlds where high-pressure ice polymorphs form. We start by (i) describing the current state of knowledge for the interior states of large icy worlds in our solar system (i.e. Ganymede, Titan and Callisto). Then we (ii) discuss the thermodynamic and physical specifics of the relevant high–pressure materials, including ices, aqueous fluids and hydrates. While doing this we (iii) describe the current state of the art in modeling and understanding the dynamic regimes of high-pressure ice mantles. Based on these considerations we (iv) explore the different evolution scenarios for large icy worlds in our solar system. We (v) conclude by discussing the implications of what we know on chemical transport from the silicate core, extrapolation to exoplanetary candidate ocean worlds, limitations to habitability, differentiation diversity, and perspectives for future space exploration missions and experimental measurements.

International audience; We document structural, geochemical, petrological and 40Ar/39Ar geochronological data performed on Variscan eclogites from the Argentera–Mercantour Massif, southwestern Alps. Based on the high-resolution field mapping, we present new eclogite occurrences and discuss the relationships between eclogites and surrounding migmatites. We recognized for the first time preserved eclogite facies assemblages. Trace elements and REE patterns establish that eclogites protoliths are MORBs contaminated by continental crust. Standard thermobarometry and thermodynamic modeling are consistent with P–T values of 640–740 °C for 1.5 ± 0.25 GPa, coherent with paleo-geotherms predicted for warm subduction of oceanic crust. We inter- pret these eclogites as a dismembered cryptic suture zone. 40Ar/39Ar dating on amphiboles yields an age of 339.7 ± 12 Ma for eclogite retrogression under amphibolite facies conditions. All these data are combined to link the Argentera–Mercantour Massif in the tectonic framework of both pre-Mesozoic Alpine basement and European southern Variscides.

This paper is a contribution to the special issue on Advances in Convection-Permitting Climate Modeling, consisting of papers that focus on the evaluation, climate change assessment, and feedback processes in kilometer-scale simulations and observations., A recently launched project under the auspices of the World Climate Research Program’s (WCRP) Coordinated Regional Downscaling Experiments Flagship Pilot Studies program (CORDEX-FPS) is presented. This initiative aims to build first-of-its-kind ensemble climate experiments of convection permitting models to investigate present and future convective processes and related extremes over Europe and the Mediterranean. In this manuscript the rationale, scientific aims and approaches are presented along with some preliminary results from the testing phase of the project. Three test cases were selected in order to obtain a first look at the ensemble performance. The test cases covered a summertime extreme precipitation event over Austria, a fall Foehn event over the Swiss Alps and an intensively documented fall event along the Mediterranean coast. The test cases were run in both “weather-like” (WL, initialized just before the event in question) and “climate” (CM, initialized 1 month before the event) modes. Ensembles of 18–21 members, representing six different modeling systems with different physics and modelling chain options, was generated for the test cases (27 modeling teams have committed to perform the longer climate simulations). Results indicate that, when run in WL mode, the ensemble captures all three events quite well with ensemble correlation skill scores of 0.67, 0.82 and 0.91. They suggest that the more the event is driven by large-scale conditions, the closer the agreement between the ensemble members. Even in climate mode the large-scale driven events over the Swiss Alps and the Mediterranean coasts are still captured (ensemble correlation skill scores of 0.90 and 0.62, respectively), but the inter-model spread increases as expected. In the case over Mediterranean the effects of local-scale interactions between flow and orography and land–ocean contrasts are readily apparent. However, there is a much larger, though not surprising, increase in the spread for the Austrian event, which was weakly forced by the large-scale flow. Though the ensemble correlation skill score is still quite high (0.80). The preliminary results illustrate both the promise and the challenges that convection permitting modeling faces and make a strong argument for an ensemble-based approach to investigating high impact convective processes., IG and LS have been supported by the Croatian Science Foundation (HrZZ) project CARE (no. 2831). JF acknowledges support by the Spanish R + D programme through MINECO/FEDER co-funded project INSIGNIA (CGL2016-79210-R). AL-G is supported by the Spanish government though grant BES-2016-078158 and MINECO/FEDER co-funded project MULTI-SDM (CGL2015-66583-R). JM and KW-S gratefully acknowledge the support by the German Science Foundation (DFG) through project FOR 1695. DM, MP, and HT gratefully acknowledge the support received via the Austrian Science Fund (FWF) project NHCM-2 (no. P24758-N29) and the projects HighEnd:Extremes and EASICLIM, funded by the Austrian Climate Research Programme (ACRP) of the Klima- und Energiefonds (nos. KR13AC6K10981 and KR16AC0K13160, respectively). SS and TL acknowledge the support of NOTUR project no. NN9280K and the Research Council of Norway and its basic institute support of their strategic project on Climate Services. RMC and PMMS gratefully acknowledge the support of the SOLAR project (PTDC/GEOMET/7078/2014) financed by the Portuguese Foundation for Science and Technology. EJ Kendon gratefully acknowledges funding from the Joint Department of Energy and Climate Change (DECC) and Department for Environment Food and Rural Affairs (Defra) Met Office Hadley Centre Climate Programme (GA01101). S. Khodayar research is supported by the Bundesministerium für Bildung und Forschung (BMBF; German Federal Ministry of Education and Research). Support of Ministry of Education, Youth and Sports of the Czech Republic for funding the participation in Euro-CORDEX activities via the scheme INTER-TRANSFER under the Grant no. LTT17007. Funding from the Research Council of Norway through the SUPER (Grant no. 250573) and HYPRE (Grant no. 243942) projects.

et al., Asteroid (2) Pallas is the largest main-belt object not yet visited by a spacecraft, making its surface geology largely unknown and limiting our understanding of its origin and collisional evolution. Previous ground-based observational campaigns returned different estimates of its bulk density that are inconsistent with one another, one measurement1 being compatible within error bars with the icy Ceres (2.16 ± 0.01 g cm−3)2 and the other3 compatible within error bars with the rocky Vesta (3.46 ± 0.03 g cm−3)4. Here we report high-angular-resolution observations of Pallas performed with the extreme adaptive optics-fed SPHERE imager5 on the Very Large Telescope. Pallas records a violent collisional history, with numerous craters larger than 30 km in diameter populating its surface and two large impact basins that could be related to a family-forming impact. Monte Carlo simulations of the collisional evolution of the main belt correlate this cratering record to the high average impact velocity of ~11.5 km s−1 on Pallas—compared with an average of ~5.8 km s−1 for the asteroid belt—induced by Pallas’s high orbital inclination (i = 34.8°) and orbital eccentricity (e = 0.23). Compositionally, Pallas’s derived bulk density of 2.89 ± 0.08 g cm−3 (1σ uncertainty) is fully compatible with a CM chondrite-like body, as suggested by its spectral reflectance in the 3 μm wavelength region6. A bright spot observed on its surface may indicate an enrichment in salts during an early phase of aqueous alteration, compatible with Pallas’s relatively high albedo of 12–17% (refs. 7,8), although alternative origins are conceivable., Based on observations collected at the European Organisation for Astronomical Research in the Southern Hemisphere under ESO programme 199.C-0074 (principal investigator: P.V.). This research has made use of the Keck Observatory Archive (KOA), which is operated by the W. M. Keck Observatory and the NASA Exoplanet Science Institute (NExScI), under contract with NASA. M.M. was supported by the National Aeronautics and Space Administration under grant number 80NSSC18K0849 issued through the Planetary Astronomy Program. This work was supported by the French Direction Générale de l’Armement (DGA) and Aix-Marseille Université (AMU). P.V., A.D. and B.C. were supported by CNRS/INSU/PNP. J.H., J.D. and P.S. were supported by the grant 18-09470S of the Czech Science Foundation and by the Charles University Research Programme number UNCE/SCI/023. M.Brož was supported by the grant 18-04514J of the Czech Science Foundation. E.J. is a F.R.S.-FNRS Senior Research Associate. The work of T.S.-R. was carried out through grant APOSTD/2019/046 by Generalitat Valenciana (Spain). This project has received funding from the European Union’s Horizon 2020 research and innovation programme under grant agreement number 730890.

International audience; The deformation of eclogites and the driving forces for their fabric development are an important topic, potentially allowing to determine deformation rates and stresses in subduction zones, where the greatest number of large earthquakes occurs. Here, fabric studies of grain size and shape, texture, and chemical composition from two locations of Variscan and Alpine eclogites are presented. All samples show a well-developed crystallographic preferred orientation (CPO) of omphacite with a strong maximum of [001] in the lineation direction and a weaker maximum of poles to (010) normal to foliation. Garnet shows no systematic CPO. Anisotropic chemical zoning developed in omphacite and garnet during growth together with elongated grain shapes and can be related to a prograde (in terms of pressure change) P,T-path. The individual chemically zoned and elongated grains orientated in the stretching direction are single crystals without major internal mis-orientations. Chemical, microstructural, and CPO data indicate that the deformation microstructure and texture were produced by preferential crystal growth of garnet and omphacite grains in the extension direction. Dislocation creep can be excluded as a possible fabric formation process by the systematic and oriented chemical zonation of single crystals and absence of dynamic recrystallization microstructures. The dominant deformation is inferred to be diffusion creep, where dissolution of material took place in reacting mafic phases (plagioclase, pyroxene) and precipitation took place in the form of new eclogite facies minerals (omphacite, garnet, zoisite). This type of diffusion creep deformation represents a transformation process involving both, deformation and metamorphic reactions. It is emphasized that the weakening is directly connected to the transformation and therefore transient. The weakening facilitates diffusion creep deformation of otherwise strong minerals (pyroxene, garnet, zoisite) at far lower stresses than dislocation creep. The results imply low stresses during the deformation of eclogite blocks in subduction zones. These results can be applied to other rock types, too.

New geochemical and geochronological data are used to characterize the geodynamic setting of metasediments, felsic orthogneisses, and eclogite and amphibolite lenses forming the Beishan complex, NW China, at the southern part of the Central Asian Orogenic Belt. The metasediments correspond compositionally to immature greywackes receiving detritus from a heterogeneous source involving a magmatic arc and a Precambrian continental crust. Metagranitoids, represented by felsic orthogneisses, show both composition of greywacke-derived granitic melt with incompatible trace element patterns similar to the host metasediments. The eclogite lenses are characterized by high Nb contents (5.34–27.3 ppm), high (Nb/La)N (>1), and low Zr/Nb ratios (

International audience; Magma transfer between lower and upper continental crust is a fundamental process linking the dominantly mafic composition of the lower crust with the more felsic composition of the upper crust. We explore the mechanisms of mafic magma ascent and emplacement in the middle crust by studying a mid-crustal gabbroic to dioritic magmatic system (Sondalo complex, Eastern Central Alps, N Italy). We characterize the structure and Anisotropy of Magnetic Susceptibility (AMS) fabric of concentric gabbroic to dioritic intrusions. The significance of AMS fabrics is discussed using Anisotropy of Anhysteretic Remanent Magnetization (AARM) and Crystallographic Preferred Orientation (CPO) data acquired on different test sites. The magmatic and magnetic fabrics of the pluton were acquired during its emplacement in the Permian and were not subsequently tilted: the fabrics are essentially vertical, indicating vertical magma transfer through the crust with a two-phase intrusion history. (1) The concordant orientation between the magmatic foliation and the host-rock xenoliths in the center of the pluton suggest that the first magma ascent phase occurred along pathways subparallel to the vertical fabric of the host metasedimentary rocks. (2) The second magma ascent phase was controlled by a change in the rheology of the host-rock and the mafic magma. Heat dissipation to the contact aureole induced partial melting, thereby lowering the mechanical strength of the host-rocks, whereas the viscosity of the mafic magma increased due to cooling and associated fractional crystallization. This caused an en-masse rise of the pluton resulting in the formation of a structural aureole, i.e. a vertical foliation in the contact aureole and a weaker but concordant magmatic foliation at the rim of the pluton. This ascent phase accounts for the P−T evolution recorded by metasedimentary rocks in the contact aureole of the pluton.

International audience; The late Carboniferous accretionary system of the South Tianshan orogen (North-Western China) underwent complex structural and polymetamorphic evolution. Combined petrological, geochronological and microstructural analysis of (ultra)high-pressure (UHP) metabasites (eclogites and blueschists) enclosed in metapelites show a relict coarse-grained eclogitic fabric S2 surrounded by a dominant fine-grained eclogite and blueschist facies retrograde fabric S2. The S2 fabric is reworked by upright folds F3 that are responsible for a major shortening of the whole accretionary system. For both the eclogite and blueschist, peak and retrograde P–T conditions have been thermodynamically constrained at 25–26 kbar and 425–500 °C and 10–13 kbar and 500−550 °C respectively, suggesting a shared exhumation history. The garnet-whole rock-amphibole isochron in the blueschist yielded Lu–Hf and Sm–Nd ages of 326.0 ± 2.9 Ma and 318.4 ± 3.9 Ma respectively, interpreted to date the prograde to peak metamorphic assemblage. The retrograde path of the eclogite is characterized by heterogeneous omphacite recrystallization into a mylonitic fine-grained matrix and crystallization of blue amphibole. Microstructures in both pristine porphyroclastic and recrystallized fine-grained domains in the eclogite indicate a gradual evolution from constriction-dominated (L>S-type) to flattening-dominated (S>L-type) type of deformation, increase of fabric intensity reflected by gradually growing M-indexes and the development of lattice preferred orientation (LPO) typical for dislocation creep under slightly hydrated conditions. Recrystallization of the matrix in the blueschist is homogeneous, which indicates a matrix dominated channel flow during exhumation. These LPOs evolutions suggest a significant mechanical coupling with the upper plate concomitant with oroclinal bending of the Kazakh orocline. Lock up of Kazakh orocline is responsible for further stress increase resulting in horizontal shortening of South Tianshan accretionary wedge and development of D3 upright folding and steepening of the whole sequence.

Highly deformed banded phengite-biotite metagranite from the Snieznik dome in the Bohemian Massif has been modified locally to have stromatic, schlieren or nebulitic textures typical of migmatites. This occurred mostly along subvertical deformation zones at eclogite-facies conditions, at a scale of several centimetres to several metres, mostly parallel to the foliation. The transition from banded to migmatite types of orthogneiss is marked by an increase in the amount of phases interstitial along grain boundaries in the dynamically recrystallized monomineralic feldspar and quartz aggregates, and by increasing consumption of recrystallized K-feldspar grains by fine-grained plagioclase and quartz, as well as myrmekite (intergrowth of Pl􏰄Qz). The new minerals are in textural equilibrium with phengite. The myrmekite, quartz and feldspars can be coarse-grained (grain size 􏰅0􏰀5cm). These features are considered to be the result of grain-scale melt infiltration that caused dissolution-reprecipitation along grain boundaries in the presence of phengite. The infiltration was pervasive at the grain scale, but localized at hand-specimen to outcrop scales. All the rock types have the same mineral assemblage of Grt􏰄+Ph+􏰄Bt+􏰄Ttn+􏰄Kfs+􏰄Pl+􏰄Qz+Rt+Ilm; they have similar garnet, phengite and biotite compositions, and based on mineral equilibria modelling we infer equilibration at a pressure of 1􏰀5-1􏰀7GPa and a temperature of 690-740􏰂C. Because the rocks are inferred to be H2O-undersaturated and above the temperature conditions of the wet solidus, infiltration must have involved a hydrous melt, as opposed to an H2O fluid. Stability of melt-bearing mineral assemblages and mineral compositions are almost independent of the melt proportion in the system, thus explaining the identical assemblage and mineral compositions observed in all the migmatite types. This precludes the estimation of the amount of melt infiltrated. Migmatite textures, however, suggest that variable degrees of melt-rock interaction occurred, being low in the banded migmatite types and higher in the nebulitic and schlieren types. Retrograde equilibration was largely restricted to retrograde zoning in phengite, garnet and plagioclase, and crystallization of biotite around phengite and garnet, presumably in a continuous reaction consuming melt. This may have occurred down to 􏰁0􏰀7-1􏰀0 GPa. According to Sr-Nd isotope data, the infiltrating melt is probably derived from similar rocks, structurally beneath the observed ones. The infiltration may have facilitated exhumation of a 2 km wide structural domain from 􏰁1􏰀7 to 􏰁0􏰀7 GPa, within which are the subvertical deformation zones along which the infiltration occurred.

The general structure of the Chinese Altai has been traditionally regarded as being formed by five tectono-stratigraphic ‘terranes’ bounded by large-scale faults. However, numerous detrital zircon studies of the Paleozoic volcano-sedimentary sequences shown that the variably metamorphosed Cambro-Ordovician sequence, known as the Habahe Group, is present at least in four ‘terranes’. It structurally represents deepest rocks unconformably covered by Devonian and Carboniferous sedimentary and volcanic rocks. Calc-alkaline, mostly Devonian, granitoids that intruded all the terranes revealed their syn-subduction related setting. Geochemistry and isotope features of the syn-subduction granitoids have shown that they originated mainly from the melting of youthful sediments derived from an eroded Ordovician arc further north. In contrast, Permian alkaline granitoids, mostly located in the southern part of the Chinese Altai, reflect a post-subduction intraplate setting. The metamorphic evolution of the metasedimentary sequences shows an early MP-MT Barrovian event, followed by two Buchan events: LP-HT mid-Devonian (ca. 400–380 Ma) and UHT-HT Permian (ca. 300–270 Ma) cycles. The Barrovian metamorphism is linked to the formation of a regional sub-horizontal possibly Early Devonian fabric and the burial of the Cambro-Ordovician sequence. The Middle Devonian Buchan type event is related to intrusions of the syn-subduction granitoids during an extensional setting and followed by Late Devonian-Early Carboniferous NE-SW trending upright folding and crustal scale doming during a general NW-SE shortening, responsible for the exhumation of the hot lower crust. The last Permian deformation formed NW-SE trending upright folds and vertical zones of deformation related to the extrusion of migmatites, anatectic granitoids and granulite rocks, and to the intrusions of gabbros and granites along the southern border of the Chinese Altai. Finally, the Permo-Triassic cooling and thrust systems affected the whole mountain range from ca. 265 to 230 Ma. In conclusion, the Chinese Altai represents different crustal levels of the lower, middle and upper orogenic crust of a single Cambro-Ordovician accretionary wedge, heterogeneously affected by the Devonian polyphase metamorphism and deformation followed by the Permian tectono-thermal reworking event related to the collision with the Junggar arc. It is the interference of Devonian and Permian upright folding events that formed vertical boundaries surrounding the variously exhumed and eroded crustal segments. Consequently, these crustal segments should not be regarded as individual suspect terranes.

International audience; Very low frequency (VLF) electromagnetic waves in the inner magnetosphere sometimes exhibit either frequency or time modulation. These phenomena are called, respectively, magnetospheric line radiation (MLR) and quasiperiodic (QP) emissions. Data from Detection of Electro‐Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) spacecraft were used to analyze their properties, such as MLR frequency spacing, QP modulation period, and QP intensity as functions of geomagnetic activity and solar wind parameters. Altogether, 1152 MLR events and 2172 QP emissions were analyzed. It is shown that the influence of the analyzed parameters on QP emissions is different for QP events with modulation periods shorter/longer than 20 s. While the properties of QP events with long modulation periods are significantly related to the geomagnetic activity and solar wind parameters, no such dependences are observed for events with short modulation periods. This suggests that there might be two types of QP emissions generated by two different mechanisms. It is further shown that there seems to be no relation between the properties of QP and MLR events observed at the same times. Finally, the event properties do not seem to be related to the whistler occurrence rate.

Este artículo contiene 13 páginas, 4 figuras, 2 tablas., Intermittent rivers and ephemeral streams (IRES) encompass fluvial ecosystems that eventually stop flowing and run dry at some point in space and time. During the dry phase, channels of IRES consist mainly of dry riverbeds (DRBs), prevalent yet widely unexplored ecotones between dry and wet phases that can strongly influence the biogeochemistry of fluvial networks. DRBs are often overlooked because they do not strictly belong to either domain of soil or freshwater science. Due to this dual character of DRBs, we suggest that concepts and knowledge from soil science can be used to expand the understanding of IRES biogeochemistry. Based on this idea, we propose that DRBs can be conceptually understood as early stage soils exhibiting many similarities with soils through two main forces: i) time since last sediment transport event, and ii) the development status of stabilizing structures (e.g. soil crusts and/or vascular plants). Our analysis suggests that while DRBs and soils may differ in master physical attributes (e.g. soil horizons vs fluvial sedimentary facies), they become rapidly comparable in terms of microbial communities and biogeochemical processes. We further propose that drivers of DRBs biogeochemistry are similar to those of soils and, hence, concepts and methods used in soil science are transferable to DRBs research. Finally, our paper presents future research directions to advance the knowledge of DRBs and to understand their role in the biogeochemistry of intermittent fluvial networks., This paper resulted from discussions conducted as part of working group 3 “Coupled Aquatic-terrestrial Biogeochemistry in IRES” based upon work from COST Action CA15113 (SMIRES, Science and Management of Intermittent rivers and Ephemeral streams; www. smires.eu) supported by COST (European Cooperation in Science and Technology). Additional support was provided for MIA by an Alexander von Humboldt Grant (Ref: 1162886) and a Juan de la Cierva Grant (Ref: FJCI-2015-26192), for CM-L by an Early Career Fellowship from the Graduate Research School (GRS) at BTU Cottbus-Senftenberg and by the French Agency for Biodiversity (ONEMA-AFB, Action 13, Colmatage, échange snappe-rivière et processus biogéochimiques), for MA by the Spanish Government (Ref: DISECO CGL-2014-55-405-R) and by a Juan de la Cierva Grant (Ref: IJCI-2015-23500), for NC by a Juan de la Cierva Grant (Ref: FJCI-2014-23064), for SB by Spanish Government (Ref: NICUS CGL-2014-55234-JIN), for RG by the Science and Technology Agency of Murcia Region (SENECA Foundation, Ref: 19525/PI/14), for OS by the SMART joint Doctorate Programme (Science for the MAnagement of Rivers and their Tidal systems, funded by the Erasmus Mundus programme of the European Union) and for Fig. 4. Conceptual framework indicating the degree of similarity in three dimensions of dry riverbeds (DRBs): physical structure, microbial community and biogeochemistry, with soils as a function of two main drivers: (T) time since the last sediment transport event, and (S) development status of stabilizing structures (e.g. biocrusts and/or vascular plants). M.I. Arce et al. Earth-Science Reviews 188 (2019) 441–453 449 DvS by the Spanish Government (Ref: CGL2016-77487-R) and Basque Government (Ref: IT951-16). Symbols for diagrams used in the art work are courtesy of the Integration and Application Network (ian.umces. edu/symbols).

International audience

International audience; The Zambezi Delta draining the Southern African Plateau and the southern part of the East African Rift is one of a the largest delta of Africa with a long-lasting history starting during Early Cretaceous with more than 12 km of sediments deposited. The Zambezi Delta is therefore a unique archive of the past topographic evolution of southern and eastern Africa and their related deformations, but also of the climate changes, global and regional (consequences of local topographic growths). Understanding this archive supposes to get a high-resolution dating of the sediments. Our two objectives are here (1) to construct an age model of the Zambezi Cenozoic delta using a combination of biostratigraphy, orbital stratigraphy and sequence stratigraphy and (2) to determine the palaeoprecipitation variations of the Zambezi catchment from the Oligocene to present day in a known tectonic framework. The Neogene sequences were dated at high-resolution assuming that the third order sequences are of eustatic origin and record long-term eccentricity cycles. The sequences were correlated in ages on the calculated Earth orbital solutions of Laskar for the time intervals provided by the biostratigraphy (nannofossils, planktonic foraminifers). The palaeoprecipitation record was based on the definition of a humidity index based on pollen analysis and associated botanical associations. The late Oligocene was a quite wet period getting dryer in the uppermost Chattian. The base Tortonian (11 Ma) was a humid period. The Messinian was a dry period with a slight increase of the humidity during the Zanclean and a sharp increase around the Zanclean-Piacenzian boundary. The Zambezi Delta has recorded the uplifts of the Southern African Plateau (around 85 Ma and around 25 Ma) and those of the southward migration of the East African Rift (since 5.5 Ma).

International audience; Electromagnetic waves generated by lightning propagate into the plasmasphere as dispersed whistlers. They can therefore influence the overall wave intensity in space which, in turn, is important for dynamics of the Van Allen radiation belts. We analyze spacecraft measurements in low‐Earth orbit as well as in high altitude equatorial region, together with a ground‐based estimate of lightning activity. We accumulate wave intensities when the spacecraft are magnetically connected to thunderstorms and compare them with measurements obtained when thunderstorms are absent. We show that strong lightning activity substantially affects the wave intensity in a wide range of L‐shells and altitudes. The effect is observed mainly between 500 Hz and 4 kHz, but its frequency range strongly varies with L‐shell, extending up to 12 kHz for L lower than 3. The effect is stronger in the afternoon, evening, and night sectors, consistent with more lightning and easier wave propagation through the ionosphere.We analyze contribution of thunderstorms to the intensity of electromagnetic radiation at audible frequencies observed at altitudes between 600 and 32,000 km, where these waves can influence the Van Allen radiation belts. We use the World Wide Lightning Location Network (WWLLN) to obtain information about lightning locations and times. Based on that, a lightning activity level is assigned to individual electromagnetic wave measurements of two spacecraft missions: the Detection of Electro‐Magnetic Emissions Transmitted from Earthquake Regions (DEMETER) and the Van Allen Probes. Subsequently, we compare median wave intensities obtained at the times of high and low lightning activity. Their ratio reveals that the radio waves originating in strong lightning storms can significantly overpower all other natural waves in a wide range of frequencies and L‐shells. The strength of this effect substantially depends on the local time. Specifically, it is the best pronounced in the afternoon/evening/night sector and nearly absent in the morning/noon sector. This agrees with the local time dependence of both, lightning occurrence and the wave attenuation in the ionosphere. The observed lightning contribution mainly occurs at frequencies over 500 Hz and with a bandwidth decreasing from 12 to 4 kHz for L between 1.5 and 5

1 Czech Geological Survey, Klarov 3, 118 21 Prague 1, Czech Republic; pavel.hanzl@geology.cz 2 Ecole et Observatoire des Sciences de la Terre, Universite de Strasbourg, UMR 7516 of CNRS, 1 rue Blessig, 67084 Strasbourg Cedex, France 3 Institute of Petrology and Structural Geology, Charles University in Prague, Faculty of Science, Albertov 6, 128 43 Prague 2, Czech Republic 4 Institute of Paleontology and Geology, Mongolian Academy of Sciences, Ulaanbaatar 15160, Mongolia 5 School of Geology and Mining Engineering, MUST, P.O. Box 654, Ulaanbaatar, Mongolia 6 State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou 510640, China * Corresponding author

International audience; We study the dynamics of radiation belt electrons during a 10-day quiet period perturbed by substorm activity and preceding a high-speed stream (HSS), aiming at a global description of the radiation belts in L-shell, L in [2, 6], and energy [0.1, 10] MeV. We combine Van Allen Probes observations and Fokker-Planck numerical simulations of pitch-angle diffusion. The Fokker-Planck model uses event-driven pitch angle diffusion coefficients from whistler-mode waves, built from the wave properties and the ambient plasma density measurements from the Van Allen Probes. We first find this event has some similar characteristics to regular quiet times previously studied; a widely extended plasmasphere within which we observe strong and varying whistler-mode waves. These ambient conditions lead to strong pitch-angle scattering, which contributes to the creation of a wide slot region as well as a significant decay of the outer radiation belts, which are observed and qualitatively well simulated. In addition, we find the substorm activity causes short duration (within ± 4h) decay of the plasma density and a lowering amplitude of the whistler-mode waves within the plasmasphere, both causing opposite effects in terms of pitch angle diffusion. This leads to a diminution of pitch-angle diffusion at the time of the main substorm activity. Conversely, whistler-mode waves become enhanced in the time periods between the substorm injections. All effects cumulated, we find an enhancement of pitch angle diffusion by whistler-mode waves above L~4.7 during the 10-day period. This directly relates to the combination of quietness and substorm activity which allows pitch angle diffusing of up to 1 MeV electrons in the outer belt. Relativistic electrons of 1–2 MeV remain trapped in the outer belt, from L~4.7 to L~5.2, forming, in both the observations and the simulations, a distinct pocket of remnant electrons.

International audience; Equatorial noise emissions are electromagnetic waves routinely observed in the equatorial region of the inner magnetosphere at frequencies between the proton cyclotron frequency and the lower hybrid frequency. Their observations are, however, typically limited to radial distances larger than about 2RE. We use the data measured by the low-altitude DEMETER spacecraft (altitude of about 700 km) to confirm that during periods of enhanced geomagnetic activity, these emissions penetrate down to low radial distances and eventually become a dominant wave emission close to the proton cyclotron frequency in the equatorial region. Wave data obtained during six intense geomagnetic storms (Dst

New petrographic and microstructural observations, mineral equilibria modelling and U/Pb (monazite) geochronological studies were carried out to investigate relationship between deformation and metamorphism across the Rehamna massif (Moroccan Variscan belt). In this area, typical Barrovian (muscovite to staurolite) zones developed in Cambrian to Carboniferous metasedimentary rocks that are distributed around a dome-like structure. First assemblages are characterized by the presence of locally preserved andalusite, followed by prograde evolution culminating at 6 kbar and 620 °C in the structurally deepest staurolite zone rocks. This Barrovian sequence was subsequently uplifted to supracrustal levels, heterogeneously reworked at greenschist facies conditions, which was followed locally by static growth of andalusite, indicating heating to 2.5−4 kbar and 530−570 °C. The 206Pb/238U monazite age of 298.3 ± 4.1 Ma is interpreted as minimum age of peak metamorphic conditions whereas the ages of 275.8 ± 1.7 Ma and 277.0 ± 1.1 Ma date decompression and heating at low pressure, in agreement with previous dating of Permian granitoids intruding the Rehamna massif. The prograde metamorphism occurred during thickening and associated horizontal flow in the deeper crust (S1 horizontal schistosity). The horizontally disposed metamorphic zones were subsequently uplifted by a regional scale antiform during ongoing N-S compression. The re-heating of the massif follows late massive E-W shortening, refolding and retrograde shearing of all previous fabrics coevally with regionally important intrusions of Permian granitoids. We argue that metamorphic evolution of the Rehamna massif occurred several hundred kilometres from the convergent plate boundaries in the interior of continental Gondwanan plate. The tectonometamorphic history of the Rehamna massif is put into Palaeozoic plate tectonic perspective and Late Carboniferous reactivation of (Devonian)-Early Carboniferous basins formed during stretching of the north Gondwana margin and formation of the Palaeotethys Ocean. The inherited heat budget of these magma-rich basins plays a role in the preferential location of this intracontinental orogen. It is shown that rapid transition from lithospheric stretching to compression is characterized by specific HT type of Barrovian metamorphism, which markedly differs from similar Barrovian sequences along Palaeozoic plate boundaries reported from Variscan Europe. This article is protected by copyright. All rights reserved.

International audience; A lot of different emissions have been detected by the low-altitude satellite DEMETER (Detection of ElectroMagnetic Emissions Transmitted from Earthquake Regions), and the aim of this paper is to study extremely low frequency (ELF) electromagnetic waves with elements drifting in frequency. It is shown that only some of them can be considered as usual chorus. These chorus elements are emitted in the equatorial plane, and their propagation analysis indicates that they are going downward at low altitudes in the ionosphere to be detected by the satellite. The study of one remarkable event recorded along the same orbit in both the Northern and the Southern Hemispheres on 8 May 2008 indicates that this propagation mechanism is reinforced at the location of the ionospheric trough, which corresponds to the plasmapause at higher altitudes. It has been observed that usual chorus elements at low frequencies are always in a frequency band which overlaps with a hiss band limited by a frequency cutoff close to the proton gyrofrequency. Other drifting elements can be attributed to emissions triggered by PLHR (power line harmonic radiation). It means that without a high-resolution spectral analysis, chorus-like elements triggered by PLHR can be wrongly considered as natural chorus. These drifting elements can also appear as filamentary structures emerging at the upper frequencies of a hiss band or quasiperiodic emissions. There are events where the elements even have certain similarities to quasiperiodic emissions. The difference between these elements and the chorus emissions will be emphasized.

International audience; Frequency-time spectrograms measured by the Detection of ElectroMagnetic Emissions Transmitted from Earthquake Regions (DEMETER) spacecraft (2004-2010, altitude about 700 km) at frequencies below 20 kHz sometimes contain lightning-generated whistlers whose intensity is significantly reduced at specific frequencies. The frequencies of the reduced intensity vary smoothly over the event duration, forming apparent curves in frequency-time spectrograms. Events at frequencies higher than the Earth-ionosphere waveguide cutoff frequency were explained by the interference of the first few waveguide modes of lightning-generated spherics propagating therein (Záhlava et al., 2015, https://doi.org/10.1002/2015JA021607. Here we present an analysis of events observed at frequencies lower than about 1 kHz. Altogether, we analyze 263 events identified at the times when DEMETER operated in the burst mode. The vast majority of the events (95%) took place during the nighttime, and they occurred more frequently during spring/autumn than during winter/summer. We present an overview of event properties. Moreover, measurements of all six electromagnetic field components performed by DEMETER allow us to perform a detailed wave analysis. It is shown that the emissions propagate with high wave normal angles inclined toward the Earth. We suggest that the events might be due to the wave propagation in the ionospheric waveguide formed around the refractive index maximum at the altitude of about 105 km.

The STAFF-DWP wave instrument on board the equatorial spacecraft (TC1) of the Double Star Project consists of a combination of 2 instruments which are a heritage of the Cluster mission: the Spatio-Temporal Analysis of Field Fluctuations (STAFF) experiment and the Digital Wave-Processing experiment (DWP). On DSP-TC1 STAFF consists of a three-axis search coil magnetometer, used to measure magnetic fluctuations at frequencies up to 4 kHz and a waveform unit, up to 10 Hz, plus snapshots up to 180 Hz. DWP provides several onboard analysis tools: a complex FFT to fully characterise electromagnetic waves in the frequency range 10 Hz-4 kHz, a particle correlator linked to the PEACE electron experiment, and compression of the STAFF waveform data. The complementary Cluster and TC1 orbits, together with the similarity of the instruments, permits new multi-point studies. The first results show the capabilities of the experiment, with examples in the different regions of the magnetosphere-solar wind system that have been encountered by DSP-TC1 at the beginning of its operational phase. An overview of the different kinds of electromagnetic waves observed on the dayside from perigee to apogee is given, including the different whistler mode waves (hiss, chorus, lion roars) and broad-band ULF emissions. The polarisation and propagation characteristics of intense waves in the vicinity of a bow shock crossing are analysed using the dedicated PRASSADCO tool, giving results compatible with previous studies: the broad-band ULF waves consist of a superimposition of different wave modes, whereas the magnetosheath lion roars are right-handed and propagate close to the magnetic field. An example of a combined Cluster DSP-TC1 magnetopause crossing is given. This first case study shows that the ULF wave power intensity is higher at low latitude (DSP) than at high latitude (Cluster). On the nightside in the tail, a first wave event comparison - in a rather quiet time interval - is shown. It opens the doors to future studies, such as event timing during substorms, to possibly determine their onset location.

Structural analysis and U–Pb geochronological study on zircons from the southern Chinese Altai (the Kalasu area, SE of the Altai city) show that the Cambro-Ordovician accretionary wedge (ca. 520–492 Ma) underwent four major geological events: 1) emplacement of Early Devonian magmas (ca. 410–400) associated with formation of a volcano-sedimentary cover, 2) major Middle Devonian (ca. 390–374 Ma) tectono-metamorphic event, 3) Late Devonian-Early Carboniferous folding without apparent metamorphism, and 4) a regional folding with localized Early Permian high- to ultrahigh-temperature reworking (ca. 300–280 Ma). The Early Devonian magmatism is characterized by emplacement of mafic rocks and granitoids in the centre of the NE-SW profile, coevally with granitoid magmatism and rhyolite volcanism in the southwest and northeast, respectively. The whole volcano-sedimentary and magmatic edifice was transposed by sub-horizontal metamorphic fabric associated with variable metamorphic degrees in different areas ranging from greenschist facies in the northeast (mu + bi±g) to amphibolite facies in the southwest (st + g ± sill) and granulite facies in the centre (g + sill+kfs). This metamorphic architecture, distribution of magmatism and character of metamorphic zircon populations allow to correlate these areas with upper, middle and lower orogenic crust that developed during important vertical shortening and horizontal flow in Middle Devonian. Subsequently, the whole edifice was affected by regional NE-SW trending upright (possibly Late Devonian-Early Carboniferous) folding. Finally, Early Permian shortening produced NW-SE trending regional upright folds in the southwest and northeast and a crustal-scale vertical, tabular deformation zone in the centre. The Permian deformation is accompanied by granulite facies (kfs + cd + sill+g) metamorphism and anatexis reworking the Devonian lower orogenic crust, with extensive resetting and growth of new zircons and with intrusions of Permian granites and gabbros. This study suggests that the Early Permian event was related to massive perturbation of thermal structure of the mantle lithosphere due to the collision of the Junggar arc with the Chinese Altai terrane.

Equatorial noise (EN) emissions are electromagnetic waves observed routinely in the equatorial region of the inner magnetosphere. Although they are typically continuous in time, they sometimes exhibit a quasiperiodic (QP) time modulation of the wave intensity, with modulation periods on the order of minutes. We perform a detailed analysis of 118 EN events with the QP modulation. The events are observed preferentially outside the plasmasphere. We determine the times and frequencies of individual QP elements forming the events. Apart from the event modulation period, this allows us to characterize the intensity and the frequency drift of individual QP wave elements. It is shown that the element intensity peaks at the magnetic equator. The modulation period within a single event is usually quite stable, with variations lower than 25% of the median value in the vast majority of cases. The events with shorter modulation periods are typically more intense, and they tend to have larger frequency drifts. These relations resemble the relations formerly revealed for extra low frequency/very low frequency quasiperiodic emissions, suggesting that the origin of the QP modulation of the wave intensity of EN and ELF/VLF emissions might be similar.

Type III bursts are generated by fast electron beams originated from magnetic reconnection sites of solar flares. As propagation of radio waves in the interplanetary medium is strongly affected by random electron density fluctuations, type III bursts provide us with a unique diagnostic tool for solar wind remote plasma measurements. Here, we performed a statistical survey of 152 simple and isolated type III bursts observed by the twin-spacecraft Solar TErrestrial RElations Observatory mission. We investigated their time–frequency profiles in order to retrieve decay times as a function of frequency. Next, we performed Monte Carlo simulations to study the role of scattering due to random electron density fluctuations on time–frequency profiles of radio emissions generated in the interplanetary medium. For simplification, we assumed the presence of isotropic electron density fluctuations described by a power law with the Kolmogorov spectral index. Decay times obtained from observations and simulations were compared. We found that the characteristic exponential decay profile of type III bursts can be explained by the scattering of the fundamental component between the source and the observer despite restrictive assumptions included in the Monte Carlo simulation algorithm. Our results suggest that relative electron density fluctuations $\langle \delta {n}_{{\rm{e}}}\rangle /{n}_{{\rm{e}}}$ in the solar wind are 0.06–0.07 over wide range of heliospheric distances.

Lu-Hf and Sm-Nd garnet-whole rock geochronology combined with petrographic observations, minero-chemical variations, thermodynamic modelling and structural data was used to constrain the P–T–t–d evolution of eclogites from the Marianske Lazně Complex (Bohemian Massif). Boudins of mostly isotropic eclogite with relict steep eclogite-facies fabric are affected by steep migmatitic foliation, which is followed on a regional scale by the development of almost pervasive, predominantly SE-dipping, extensional foliation. The structural succession shows continuous transition from eclogite to garnetiferous migmatitic amphibolite and to amphibolite migmatite. A least retrogressed sample of eclogite shows clusters of fine-grained inclusion-poor garnet, omphacite relicts surrounded by a fine-grained clinopyroxene-plagioclase symplectite with minor amphibole, biotite-plagioclase intergrowths after white mica, kyanite with plagioclase-spinel coronas and accessory rutile. Rare potassic white mica occurs as inclusions in omphacite. A more retrogressed eclogite, with no omphacite or kyanite relicts, contains inclusion-poor garnet surrounded by amphibole-plagioclase corona in a matrix dominated by plagioclase-amphibole symplectite with minor clinopyroxene. In places, the symplectite is overgrown by coarse-grained amphibole. Peak P–T conditions, inferred from combined conventional thermobarometry and phase-equilibria modelling and based on inclusions of white mica (up to 3.33 Si p.f.u.), matrix omphacite (Jd33–36) and garnet core (Alm33–38Prp38–42Grs22–25Sps1) compositions are ~25 kbar at 650–750 °C. A HT overprint occurred at ~14–18 kbar and >800 °C based on coexisting clinopyroxene (Jd18–24), plagioclase (An18–35), and amphibole (Na(B) Lu-Hf and Sm-Nd garnet geochronology has been applied to both samples, an older age (c. 390 Ma) obtained by the Lu-Hf method is interpreted as the timing of HP metamorphism, while c. 15 Ma younger ages were obtained by the Sm-Nd method. As temperatures for the HT overprint exceed the empirically and experimentally determined closure temperature of the Sm-Nd system the Sm-Nd ages are interpreted to date cooling following the HT overprint. Combined together, contrasting eclogite and amphibolite-facies migmatite fabrics, the mineral textures, calculated P–T conditions, and distinct Lu-Hf and Sm-Nd ages, provide a complete P–T–t–D path characterised by rapid (~15 Ma) transition from HP subduction, crustal thickening to extensional HT shearing. This unconventional exhumation path does not fit to models of monocyclic exhumation in a subduction channel proposed for the Munchberg and ZEV Devonian HP units to the west. In contrast, the post-peak extensional low angle shearing shortly after subduction and collision resembles more the geodynamic model typical for the Iberian subduction system both in time scales and sequence of tectonic events.

International audience

International audience; Assessment of sediment redistribution by end-Ordovician ice sheets is crucial for the reconstruction of Lower Paleozoic source-to-sink patterns. Focusing on the ice-distal, deepwater Tazekka depocenter (Moroccan Meseta), we performed a provenance study that combined whole-rock geochemistry, petrography and insights from high-resolution detrital zircon ages. The results show that the glacigenic sediments are compositionally — mineralogically and geochemically — more mature than preglacial strata. This observation points to a preferential cannibalization of the “great Lower Paleozoic quartz-rich sandstone sheet”, with a limited input of first-cycle, far-travelled clastic sediments. Differentiation of glacial units is not straightforward, yet the glaciation acme is typified by a highly mature sedimentary source and an age spectrum lacking Mesoproterozoic zircon grains, both features strongly indicating derivation from the Cambrian–Lower Ordovician cover of the Tuareg Shield. More regional sources are expressed during the earlier glaciation stages, during which lowstand remobilizations unrelated to subglacial erosion are also suspected. Subordinate but notable late Tonian (∼0.8 Ga) and latest Stenian to early Tonian (∼1 Ga) zircon populations are also evidenced in Morocco, which may have implications for future paleogeographic reconstructions.

Acceso electrónico sólo desde el IGME, Landslides are one of the most widespread geohazards in Europe, producing significant social and economic impacts. Rapid population growth in urban areas throughout many countries in Europe and extreme climatic scenarios can considerably increase landslide risk in the near future. Variability exists between European countries in both the statutory treatment of landslide risk and the use of official assessment guidelines. This suggests that a European Landslides Directive that provides a common legal framework for dealing with landslides is necessary. With this long-term goal in mind, this work analyzes the landslide databases from the Geological Surveys of Europe focusing on their interoperability and completeness. The same landslide classification could be used for the 849,543 landslide records from the Geological Surveys, from which 36% are slides, 10% are falls, 20% are flows, 11% are complex slides, and 24% either remain unclassified or correspond to another typology. Most of them are mapped with the same symbol at a scale of 1:25,000 or greater, providing the necessary information to elaborate European-scale susceptibility maps for each landslide type. A landslide density map was produced for the available records from the Geological Surveys (LANDEN map) showing, for the first time, 210,544 km2 landslide-prone areas and 23,681 administrative areas where the Geological Surveys from Europe have recorded landslides. The comparison of this map with the European landslide susceptibility map (ELSUS 1000 v1) is successful for most of the territory (69.7%) showing certain variability between countries. This comparison also permitted the identification of 0.98 Mkm2 (28.9%) of landslide-susceptible areas without records from the Geological Surveys, which have been used to evaluate the landslide database completeness. The estimated completeness of the landslide databases (LDBs) from the Geological Surveys is 17%, varying between 1 and 55%. This variability is due to the different landslide strategies adopted by each country. In some of them, landslide mapping is systematic; others only record damaging landslides, whereas in others, landslide maps are only available for certain regions or local areas. Moreover, in most of the countries, LDBs from the Geological Surveys co-exist with others owned by a variety of public institutions producing LDBs at variable scales and formats. Hence, a greater coordination effort should be made by all the institutions working in landslide mapping to increase data integration and harmonization., Earth Observation and Geohazards Expert Group (EOEG), EuroGeoSurveys, the Geological Surveys of Europe, Bélgica, Geohazards InSAR Laboratory and Modeling Group, Instituto Geológico y Minero de España, España, Risk and Prevention Division, Bureau de Recherches Géologiques et Minières, Francia, Engineering Geology Department, Institute of Geology and Mineral Exploration, Grecia, GeoHazard team, Geological Institute of Romania, Rumanía, Geological Survey of Slovenia, Eslovenia, Croatian Geological Survey, Croacia, Italian Institute for Environmental Protection and Research, Geological Survey of Italy, Italia, Swiss Federal Office for the Environment, Suiza, Geological Survey of Austria, Austria, Polish Geological Institute, National Research Institute, Polonia, Geological Survey of Ireland, Irlanda, Czech Geological Survey, República Checa, Federal Institute for Geosciences and Natural Resources, Alemania, Geological Survey of Norway, Noruega, Cyprus Geological Survey, Chipre, Geological Survey of Sweden, Suecia, Institut Cartogràfic i Geològic de Catalunya, España, British Geological Survey, Reino Unido, Geological Survey of Slovakia, Eslovaquia, Geological Survey of Lithuania, Lituania, Federalni zavod za geologiju, Bosnia y Herzegovina, Geological Survey of Estonia, Estonia, Laboratório Nacional de Energia e Geologia, Portugal, Geological Survey of Hungary, Hungría, Norwegian Water and energy Directorate of Norway, Noruega