ALBERT

Description: We present a new GPS velocity field covering the peri-Adriatic tectonically-active belts and the entire Balkan Peninsula. From the velocities, we calculate consistent strain rate and interpolated velocity fields. Significant features of the crustal deformation include: (1) the eastward motion of the northern part of the Eastern Alps together with part the Alpine foreland and Bohemian Massif towards the Pannonian Basin, (2) shortening across the Dinarides, (3) a clock-wise rotation of the Albanides-Hellenides and (4) a southward motion South of 44 ∘ N of the inner Balkan lithosphere between the rigid Apulia and Black Sea, towards the Aegean domain. Using this new velocity-field, we derive the strain rate tensor to analyze the regional style of the deformation. Then, we devise a simple test based on the momentum balance equation, to investigate the role of horizontal gradients of gravitational potential energy in driving the deformation in the Peri-Adriatic tectonically-active mountain belts : the Eastern Alps, the Dinarides, the Albanides and the Apennines. We show that the strain rate fields observed in the Apennines and Albanides are consistent with a fluid, with viscosity η ∼ 3×10 21 Pas, deforming in response to horizontal gradients of gravitational potential energy. Conversely, both the Dinarides and Eastern Alps are probably deforming in response to the North and North-East oriented motion of the Adria-Apulia indenter respectively, and as a consequence of horizontal lithospheric heterogeneity.

Description: Developing better agricultural monitoring capabilities based on Earth Observation data is critical for strengthening food production information and market transparency. The Sentinel-2 mission has the optimal capacity for regional to global agriculture monitoring in terms of resolution (10–20 meter), revisit frequency (five days) and coverage (global). In this context, the European Space Agency launched in 2014 the “Sentinel­2 for Agriculture” project, which aims to prepare the exploitation of Sentinel-2 data for agriculture monitoring through the development of open source processing chains for relevant products. The project generated an unprecedented dataset, made of “Sentinel-2 like” time series and in situ data acquired in 2013 over 12 globally distributed sites. Earth Observation time series were mostly built on the SPOT4 (Take 5) data set, which was specifically designed to simulate Sentinel-2. They also included Landsat 8 and RapidEye imagery as complementary data sources. Images were pre-processed to Level 2A and the quality of the resulting time series was assessed. In situ data about cropland, crop type and biophysical variables were shared by site managers, most of them belonging to the “Joint Experiment for Crop Assessment and Monitoring” network. This data set allowed testing and comparing across sites the methodologies that will be at the core of the future “Sentinel­2 for Agriculture” system.

Description: The Owen Fracture Zone is a 800 km-long fault system that accommodates the dextral strike-slip motion between India and Arabia plates. Because of slow pelagic sedimentation rates that preserve the seafloor expression of the fault since the Early Pliocene, the fault is clearly observed on bathymetric data. It is made up of a series of fault segments separated by releasing and restraining bends, including a major pull-apart basin at latitude 20°N. Some distal turbiditic channels from the Indus deep-sea fan overlap the fault system and are disturbed by its activity, thus providing landmarks to date successive stages of fault activity and structural evolution of the Owen Fracture Zone from Pliocene to Present. We determine the durability of relay structures and the timing of their evolution along the principal displacement zone, from their inception to their extinction. We observe subsidence migration in the 20°N basin, and alternate activation of fault splays in the vicinity of the Qalhat seamount. The present-day Owen Fracture Zone is the latest stage of structural evolution of the 20-Myr-old strike-slip fault system buried under Indus turbiditic deposits whose activity started at the eastern foot of the Owen Ridge when the Gulf of Aden opened. The evolution of the Owen Fracture Zone since 3–6 Myr reflects a steady state plate motion between Arabia and India, such as inferred by kinematics for the last 20 Myr period. The structural evolution of the Owen Fracture Zone since 20 Myr, including fault segments propagation and migration, pull-apart basin opening and extinction, seems to be characterized by a progressive reorganization of the fault system, and does not require any major kinematics change.

Description: We present a new kinematic and strain model of an area encompassing the Calabrian and Hellenic subduction zones, western Anatolia and the Balkans. Using Haines and Holt's (1993) method, we derive continuous velocity and strain rate fields by interpolating geodetic velocities, including recent GPS data in the Balkans. Relative motion between stable Eurasia and the western Aegean Sea is gradually accommodated by distributed N-S extension from Southern Balkans to the Eastern Corinth Gulf, so that the westward propagation of the North Anatolian Fault (NAF) throughout continental Greece or Peloponnesus is not required. We thus propose that the NAF terminates in north Aegean and that N-S extension localized in the Corinth Gulf and distributed in Southern Balkans is due to the retreat of the Hellenic slab. The motion of the Hyblean plateau, Apulia Peninsula, south Adriatic Sea, Ionian Basin and Sirte plain can be minimized by a single rigid rotation around a pole located in the Sirte plain, compatible with the opening the Pelagian rifts (2–2.5 mm/yr) and seismotectonics in Libya. We interpret the trenchward ultraslow motion of the Calabrian arc (2–2.5 mm/yr) as pure collapse, the Calabrian subduction being now inactive. In the absolute plate motion reference frame, our modeled velocity field depicts two toroïdal crustal patterns located at both ends of the Hellenic subduction zone, clockwise in NW Greece and counter-clockwise in western Anatolia. We suggest the NW Greece toroïdal pattern is the surface expression of a slab tear and consequent toroïdal asthenospheric flow.

Description: Orogen-parallel extension and orogen-perpendicular shortening accommodated by folding acted at the same time to exhume the Tauern Window. In order to investigate the relative contribution of upright folding and erosion and of extensional denudation for exhumation we provide compilations in map view of previous and new zircon and apatite fission-track ages. These age maps show that iso-age contour lines are sub-parallel to the axial-planes of large-scale, upright folds. On age vs. distance diagrams, along a profile perpendicular to the dome axis, all thermochronometers show bell-shaped curves with younger ages in the hinge area of the dome and and age differences between different chronometers decreasing from the limbs to the hinge area. All these observations suggest that folding synchronous with erosion was largely responsible for exhumation of the Tauern Window. The younger ages and the higher fold amplitudes of the western subdome compared to the eastern one are corroborated by the results of inversion of cooling ages that show higher exhumation rates in the west. These reflect one and the same shortening and folding event that affected the entire Tauern Dome synchronously, but at higher rates of in the western subdome. Only during Pliocene time exhumation rates were slightly higher along the normal faults bordering the Window, hence extensional unroofing may have dominated exhumation in the Pliocene. The northward displacement of the Dolomites Indenter was associated to a clockwise rotation, which caused increased amounts of shortening westward, hence higher uplift- and exhumation rates in the western subdome.

Description: The geodynamic processes in the western Mediterranean are driven by both deep (mantle) processes such as slab-rollback or delamination, oblique plate convergence and inherited structures. The present-day deformation of the Alboran Sea and in particular the Nekor basin area is linked to these coeval effects. The seismically active Nekor basin is an extensional basin formed in a convergent setting at the eastern part of the Rif Chain whose boundaries extend both onshore and offshore Morocco. We propose a new structural model of the Nekor basin based on high-resolution offshore data compiled from recent seismic reflection profiles, swath bathymetry acquisitions and industrial seismic reflection profiles. The new data set shows that the northern limit of the basin is oriented N49° with right-stepping faults from the Bousekkour–Aghbal fault to the sinistral Bokkoya fault zone. This pattern indicates the presence of an inherited left-lateral basement fault parallel to the major inherited Nekor fault. This fault has been interpreted as a Quaternary active left-lateral transfer fault localized on weak structural discontinuities inherited from the orogenic period. Onshore and offshore active faults enclose a rhombohedral tectonic Nekor Basin. Normal faults oriented N155° offset the most recent Quaternary deposits in the Nekor basin, and indicate the transtensional behaviour of this basin. The geometry of these faults suggests a likely rollover structure and the presence at depth of a crustal detachment. Inactive Plio-Quaternary normal faults to the east of the Ras Tarf promontory and geometries of depocentres seem to indicate the migration of deformation from east to west. The local orientations of horizontal stress directions deduced from normal fault orientations are compatible with the extrusion of the Rifian units and coherent with the westward rollback of the Tethyan slab and the localization of the present-day slab detachment or delamination. © 2016 The Authors. Basin Research © 2016 John Wiley & Sons Ltd, European Association of Geoscientists & Engineers and International Association of Sedimentologists