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EPOS, the European Plate Observing System, is a unique e-infrastructure and collaborative environment for the solid earth science community in Europe and beyond (https://www.epos-eu.org/). A wide range of world-class experimental (analogue modelling and rock and melt physics) and analytical (paleomagnetic, geochemistry, microscopy) laboratory infrastructures are concerted in a “Thematic Core Service” (TCS) labelled “Multi-scale Laboratories” (MSL) (https://www.epos-eu.org/tcs/multi-scale-laboratories). Setting up mechanisms allowing for sharing metadata, data, and experimental facilities has been the main target achieved during the EPOS implementation phase. The TCS Multi-scale Laboratories offers coordination of the laboratories’ network, data services, and Trans-National access to laboratory facilities.In the framework of data services, TCS Multi-Scale Laboratories promotes FAIR (Findable-Accessible-Interoperable-Re-Usable) (FAIR) sharing of experimental research data sets through Open Access data publications. Data sets are assigned with digital object identifiers (DOI) and are published under the CC BY license. Data publications are now conventionally citable in scientific journals and develop rapidly into a common bibliometric indicator and research metric. A dedicated metadata scheme (following international standards that are enriched with disciplinary controlled community vocabulary) facilitates ease exploration of the various data sets in a TCS catalogue (https://epos-msl.uu.nl/). Concerning analogue modelling, a growing number of data sets includes analogue material physical and mechanical properties and modelling results (raw data and processed products such as images, maps, graphs, animations, etc.) as well as software (for visualization, monitoring and analysis). The main geoscience data repository is currently GFZ Data Services, hosted at GFZ German Research Centre for Geosciences (https://dataservices.gfz-potsdam.de), but others are planned to be implemented within the next years.In the framework of Trans-National access (TNA), TCS Multi-scale laboratories’ facilities are accessible to any researchers, creating new opportunities for synergy, collaboration and scientific innovation, according to TNAtrans-national access rules. TNA can be realized in the form of physical access (on-site experimenting and analysis), remote service (sample analysis) and virtual access (remotely operated processing). After three successful TNA calls, the pandemic has forced a moratorium on the TNA program.The EPOS TCS Multiscale Laboratories framework is also providing the foundation for a comprehensive database of rock analogue materials, a dedicated bibliography, and facilitates the organization of community-wide activities (e.g., meetings, benchmarking) to stimulate collaboration among analogue laboratories and the exchange of know-how. Recent examples of these community efforts are also the contributions to the monthly MSL seminars, available on the MSL YouTube channel (https://www.youtube.com/channel/UCVNQFVql_TwcSBqgt3IR7mQ/featured), as well as the Special Issue on basin inversion in Solid Earth that is currently open for submissions (https://www.solid-earth.net/articles_and_preprints/scheduled_sis.html#1160).

Orogeny results from crustal thickening at active margins, and much progress has been made on understanding the associated kinematics. However, the ultimate cause of orogeny is still debated, especially for the case of extreme crustal thickening. Inspired by the seminal work of Holmes (1931), we explore the connections between the style of orogeny and mantle dynamics. We distinguish between two types of orogeny, those that are associated with one-sided, mainly upper mantle subduction, “slab-pull orogeny”, and those related to more symmetric, whole mantle convection cells, referred to as “mantle”, or “slab-suction orogeny”. Only the latter leads to extreme crustal thickening. We propose that mantle orogeny is generated by the penetration of slabs into the lower mantle and the associated change in the length scales of convection. This suggestion is supported by numerical dynamic models which show that upper plate compression is associated with slab penetration into the lower mantle. Slabs can further trigger a buoyant, plume upwelling from the core-mantle boundary which enhances this whole mantle convection cell, and with it upper plate compression. We explore the geological record to test the validity of such a model. For the present-day, compressional backarc regions are commonly associated with slabs that subduct to the deep lower mantle. The temporal evolution of the Nazca and Tethyan slabs with the associated Andean Cordillera and the Tibetan-Himalayan orogenies likewise suggests that extreme crustal thickening below the Bolivia and Tibetan plateau occurred during slab penetration into the lower mantle. This episode of crustal thickening in the Tertiary bears similarity with Pangea assembly events, where the Gondwanide accretionary orogen occurred at the same time of the Variscan-Appalachian and Ural orogeny. We propose that this Late Paleozoic large-scale compression is likewise related to a change from transient slab ponding in the transition zone to lower mantle subduction. If our model is correct, the geological record of orogeny in continental lithosphere can be used to decipher time-dependent mantle convection, and episodic lower mantle subduction may be causally related to the supercontinental cycle.

EPOS, the European Plate Observing System, is a unique e-infrastructure and collaborative environment for the solid earth science community in Europe and beyond. A wide range of world-class experimental (analogue modelling and rock and melt physics) and analytical (paleomagnetic, geochemistry, microscopy) laboratory infrastructures are concerted in a “Thematic Core Service” (TCS) labelled “Multi-scale Laboratories” (MSL). Sharing experimental facilities and data on analogue modelling of tectonic processes as well as on properties and applicability of different rock analogue materials are among the thematic areas that have been achieved during the current implementation phase of EPOS. The TCS Multi-scale Laboratories offers coordination of the laboratories’ network, data services, and trans-national access to laboratory facilities. In the framework of Transnational Access (TNA), TCS Multi-scale laboratories’ facilities are accessible to researchers across the world, creating new opportunities for synergy, collaboration and scientific innovation, according to trans-national access rules. TNA can be realized in the form of physical access (in-situ experimenting and analysis), remote service (sample analysis) and virtual access (remote processing). After three successful TNA calls, the 2020 and 2021 TNA calls have been suspended due to Covid-19 pandemic restrictions. A TNA call is now foreseen for 2022 offering access to a variety of experimental facilities and complementary expertise. In the framework of data services, TCS Multi Scale Laboratories promotes FAIR (Findable-Accessible-Interoperable-Re-Usable) sharing of experimental research data sets through Open Access data publications. Data sets are assigned with digital object identifiers (DOI) and are published under open CC BY licences. They are thus citable in all relevant scientific journals. A dedicated metadata schema (following international standards that are enrichiched with disciplinary controlled community vocabulary) eases exploration of the various data sets in a TCS catalogue. With respect to analogue modelling, a growing number of analogue modelling data sets include analogue material properties (friction and rheology data) and modelling results (images, maps, graphs, animations) as well as software (visualization and analysis). The main repository for data sets is currently GFZ Data Services, a domain repository for Geosciences, hosted at GFZ German Research Centre for Geosciences, but others are planned to be implemented within the next years. The EPOS TCS Multiscale Laboratories framework will lay the foundation for a comprehensive database of rock analogue materials, a dedicated bibliography, and will facilitate the organization of community wide activities (eg. meetings, benchmarking, etc.) to stimulate collaboration among analogue laboratories and the exchange of know-how.

The Apennines is a well-studied orogeny formed by the accretion of continental slivers during the subduction of the Adriatic plate, but its deep structure is still a topic of controversy. Here we illuminated the deep structure of the Northern Apennines belt by combining results from the analysis of active seismic (CROP03) and receiver function data. The result from combining these two approaches provides a new robust view of the structure of the deep crust/upper mantle, from the back-arc region to the Adriatic subduction zone. Our analysis confirms the shallow Moho depth beneath the back-arc region and defines the top of the downgoing plate, showing that the two plates separate at depth about 40km closer to the trench than reported in previous reconstructions. This spatial relationship has profound implications for the geometry of the shallow subduction zone and of the mantle wedge, by the amount of crustal material consumed at trench.

Highlights • Plate boundary re-organization in the central Mediterranean Sea • Segmentation of the subduction complex along lithospheric transverse faults • STEP faults in the Ionian Sea • Pleistocene active faulting and Mt. Etna formation Abstract The Calabrian Arc is a narrow subduction-rollback system resulting from Africa/Eurasia plate convergence. While crustal shortening is taken up in the accretionary wedge, transtensive deformation accounts for margin segmentation along transverse lithospheric faults. One of these structures is the NNW-SSE transtensive fault system connecting the Alfeo seamount and the Etna volcano (Alfeo-Etna Fault, AEF). A second, NW-SE crustal discontinuity, the Ionian Fault (IF), separates two lobes of the CA subduction complex (Western and Eastern Lobes) and impinges on the Sicilian coasts south of the Messina Straits. Analysis of multichannel seismic reflection profiles shows that: 1) the IF and the AEF are transfer crustal tectonic features bounding a complex deformation zone, which produces the downthrown of the Western lobe along a set of transtensive fault strands; 2) during Pleistocene times, transtensive faulting reactivated structural boundaries inherited from the Mesozoic Tethyan domain which acted as thrust faults during the Messinian and Pliocene; 3) the IF and the AEF, and locally the Malta escarpment, accommodate a recent tectonic event coeval and possibly linked to the Mt. Etna formation. Regional geodynamic models show that, whereas AEF and IF are neighboring fault systems, their individual roles are different. Faulting primarily resulting from the ESE retreat of the Ionian slab is expressed in the northwestern part of the IF. The AEF, on the other hand, is part of the overall dextral shear deformation, resulting from differences in Africa-Eurasia motion between the western and eastern sectors of the Tyrrhenian margin of northern Sicily, and accommodating diverging motions in the adjacent compartments, which results in rifting processes within the Western Lobe of the Calabrian Arc accretionary wedge. As such, it is primarily associated with Africa-Eurasia relative motion.

Collision with and subduction of an oceanic plateau is a rare and transient process that usually leaves an indirect imprint only. Through a tectonostratigraphic analysis of pre-Oligocene sequences in the San Jacinto fold belt of northern Colombia, we show the Late Cretaceous to Eocene tectonic evolution of northwestern South America upon collision and ongoing subduction with the Caribbean Plate. We linked the deposition of four fore-arc basin sequences to specific collision/subduction stages and related their bounding unconformities to major tectonic episodes. The Upper Cretaceous Cansona sequence was deposited in a marine fore-arc setting in which the Caribbean Plate was being subducted beneath northwestern South America, producing contemporaneous magmatism in the present-day Lower Magdalena Valley basin. Coeval strike-slip faulting by the Romeral wrench fault system accommodated right-lateral displacement due to oblique convergence. In latest Cretaceous times, the Caribbean Plateau collided with South America marking a change to more terrestrially influenced marine environments characteristic of the upper Paleocene to lower Eocene San Cayetano sequence, also deposited in a fore-arc setting with an active volcanic arc. A lower to middle Eocene angular unconformity at the top of the San Cayetano sequence, the termination of the activity of the Romeral Fault System, and the cessation of arc magmatism are interpreted to indicate the onset of low-angle subduction of the thick and buoyant Caribbean Plateau beneath South America, which occurred between 56 and 43Â Ma. Flat subduction of the plateau has continued to the present and would be the main cause of amagmatic post-Eocene deposition.

International audience; The Sila Massif is a small part of an orogenic wedge that sits on top of the narrow and active Calabrian subduction zone. The topography of the Sila Massif is characterized by a plateau region whose age and origin has been long debated. Here we integrate new apatite (U-Th)/He data from the eastern flank of the massif with existing apatite fission-track (AFT) data, to constrain the topographic evolution of the massif. The new AHe ages range from 9.7 Ma to 49.8 Ma and overlap the AFT ages indicating that a phase of rapid Cenozoic exhumation was followed by an abrupt decrease of the exhumation rate. A steep/inverse AFT age-elevation relationship from a vertical profile on top of the summit area of the north-eastern Sila may records post-exhumation relief degradation, which is consistent with the low-relief upland topography. To test this hypothesis we performed inverse numerical modeling using Pecube code. Integrating the new AHe ages and the numerical modelling results with the geological constraints we propose a new model for the regional topographic evolution from 30 Ma to the present.

The Mediterranean offers a unique opportunity to study the driving forces of tectonic deformation within a complex mobile belt. Lithospheric dynamics are affected by slab rollback and collision of two large slowly moving plates forcing fragments of continental and oceanic lithosphere to interact. This paper reviews the rich and growing set of constraints from geological reconstructions geodetic data and crustal and upper mantle heterogeneity imaged by structural seismology. We proceed to discuss a conceptual and quantitative framework for the causes of surface deformation. Exploring existing and newly developed tectonic and numerical geodynamic models we illustrate the role of mantle convection on surface geology. A coherent picture emerges which can be outlined by two almost symmetric upper mantle convection cells. The downwellings are found in the center of the Mediterranean and are associated with the descent of the Tyrrhenian and the Hellenic slabs. During plate convergence these slabs migrated backward with respect to the Eurasian upper plate inducing a return flow of the asthenosphere from the back arc regions toward the subduction zones. This flow can be found at large distance from the subduction zones and is at present expressed in two upwellings beneath Anatolia and eastern Iberia. This convection system provides an explanation for the general pattern of seismic anisotropy in the Mediterranean first order Anatolia and Adria microplate kinematics and may contribute to the high elevation of scarcely deformed areas such as Anatolia and eastern Iberia. More generally the Mediterranean is an illustration of how upper mantle small scale convection leads to intraplate deformation and complex plate boundary reconfiguration at the westernmost terminus of the Tethyan collision.

Since the first discovery of ultrahigh pressure (UHP) rocks 30 years ago in the Western Alps, the mechanisms for exhumation of (U)HP terranes worldwide are still debated. In the western Mediterranean, the presently accepted model of synconvergent exhumation (e.g., the channel-flow model) is in conflict with parts of the geologic record. We synthesize regional geologic data and present alternative exhumation mechanisms that consider the role of divergence within subduction zones. These mechanisms, i.e., (i) the motion of the upper plate away from the trench and (ii) the rollback of the lower plate, are discussed in detail with particular reference to the Cenozoic Adria-Europe plate boundary, and along three different transects (Western Alps, Calabria-Sardinia, and Corsica-Northern Apennines). In the Western Alps, (U)HP rocks were exhumed from the greatest depth at the rear of the accretionary wedge during motion of the upper plate away from the trench. Exhumation was extremely fast, and associated with very low geothermal gradients. In Calabria, HP rocks were exhumed from shallower depths and at lower rates during rollback of the Adriatic plate, with repeated exhumation pulses progressively younging toward the foreland. Both mechanisms were active to create boundary divergence along the Corsica-Northern Apennines transect, where European southeastward subduction was progressively replaced along strike by Adriatic northwestward subduction. The tectonic scenario depicted for the Western Alps trench during Eocene exhumation of (U)HP rocks correlates well with present-day eastern Papua New Guinea, which is presented as a modern analog of the Paleogene Adria-Europe plate boundary.