Polyphase evolution of Pelagonia (northern Greece) revealed by geological and fission-track data
Summary: The eastern Mediterranean is a long-lived seismically active region where the interaction of compressive and extensive tectonics is responsible for complex crustal deformation. The Pelagonian zone in the Hellenides has witnessed such deformational processes since the Mesozoic. This study combines fission-track analysis (recording temperatures <240°C), structural and stratigraphic data that were essential to constrain the polyphase evolution of the Hellenic orogen over 100 Ma.
A 3-D shear velocity model of the southern North American and Caribbean plates from ambient noise and earthquake tomography
Summary: We compute a velocity model of the crust and uppermost mantle of southern North America, Mexico and the Caribbean. We use a recent technique based on "ambient noise" (or continuous seismic records) and a traditional one using earthquakes. Both techniques, together with the increased number of seismic stations in the region, allow us to obtain greater resolution than previous works. Some of its applications are to localize regional earthquakes and simulate ground motions.
The rheological behaviour of fracture-filling cherts: example of Barite Valley dikes, Barberton Greenstone Belt, South Africa
Summary: We investigate the composition, physical and rheological properties of fluids at the origin of Palaeoarchean chert dikes in South Africa. The dikes formed by repetitive hydraulic fracturing as overpressured oceanic fluids were released at low temperatures as a siliceous slurry. The gelation capacity of silica conferred the chert precursor a viscoelastic, probably thixotrope behaviour. It is an additional step to understand fluid circulations towards the ocean floor, the habitat of early life.
Soil microbiological properties and enzymatic activities of long-term post-fire recovery in dry and semiarid Aleppo pine (Pinus halepensis M.) forest stands
Summary: Soil properties, as well as biochemical, microbiological, and physicochemical properties of an burned Aleppo pine stand had the ability to recover 17 years after fire, showing similar values than a not-burned mature Aleppo pine stand. These properties had also recovered after 12 years of carrying out silvicultural management as thinning.
Volcanological aspects of the northwest region of Paraná continental flood basalts (Brazil)
Summary: This study describes for the first time morphological aspects of lava flows and structural characteristics caused by lava-sediment interaction in the northwestern Paraná continental flood basalts in the southeast of the South American Plate (Brazil). Early Cretaceous (134 to 132Ma) tholeiitic rocks were emplaced on a large intracratonic Paleozoic sedimentary basin (Paraná Basin), mainly covering dry eolian sandstones (Botucatu Formation).
Variations of the crustal thickness in Nepal Himalayas based on tomographic inversion of regional earthquake data
Summary: We estimate variations of the crustal thickness beneath the Nepal Himalayas based on tomographic inversion of regional earthquake data. The obtained variations of crustal thickness match fairly well with the free-air gravity anomalies and correlate with magnetic field. We propose that elevated magnetic values can be associated with more rigid segments of the incoming Indian crust which cause more compression in the thrust zone and lead to stronger crustal thickening.
A lithosphere-scale structural model of the Barents Sea and Kara Sea region
Summary: We introduce a regional 3-D structural model of the Barents Sea and Kara Sea region which is the first to combine information on five sedimentary units and the crystalline crust as well as the configuration of the lithospheric mantle. By relating the shallow and deep structures for certain tectonic subdomains, we shed new light on possible causative basin-forming mechanisms that we discuss.
Effective buoyancy ratio: a new parameter for characterizing thermo-chemical mixing in the Earth's mantle
Summary: The effective buoyancy ratio was introduced as a diagnostic tool to characterize the evolution of the thermo-chemical mixing in the Earth’s mantle. This parameter tracks the fate of the primordial compositionally dense layer above the core–mantle boundary such as (i) the transition phase of warming dense layer; (ii) the erosion and dilution of the dense layer; (iii) the effective thermo-chemical convection (mixing of layers) and (iv) the homogenization.
Finite-difference modelling to evaluate seismic P-wave and shear-wave field data
Summary: In this paper, we compared, measured and simulated reflection seismology data for different wave types. P wave and shear wave land data were acquired in the field while the synthetic data were generated by finite-difference modelling. Major features of the P waves were imaged, but simulations cannot clarify the signal-to-noise ratio of the shear wave field data. Future modelling approaches will consider additional features for a better understanding of near-surface seismic measurements.
Analogue experiments of salt flow and pillow growth due to basement faulting and differential loading
Summary: This paper summarizes the results of scaled analogue experiments examining the kinematics of salt flow and the formation of salt pillows due to basement faulting and subsequent sedimentation. Our experimental results reveal that salt above a basement normal fault can flow downward or upward depending on the direction of the pressure gradient within the salt layer. Due to upward flow driven by differential loading, salt pillows can form above the higher basement block.