Transverse Zone Research Articles

Maastrichtian to Palaeocene and Eocene pelagic carbonates on the island of Svetac (central Adriatic, Croatia)

Maastrichtian to Palaeocene pelagic carbonates on the central Adriatic island of Svetac (Sveti Andrija) are the only outcrops reported to date that document pelagic deposition during the Cretaceous–Palaeogene (K–Pg) transition within the Adriatic Basin. An approximately 3 m thick succession at the Smokvica locality contains a rich and diverse planktonic foraminiferal assemblage which allows dating of the succession and the recognition of some biostratigraphic zones. The lower part of the Smokvica section consists of 1.5 m thick pelagic biomicrite characterized by the abundance of late Maastrichtian planktonic foraminifera that indicate the Abathomphalus mayaroensis Zone. An intercalation of intraclastic floatstone <0.5 m in thickness occurring on top of Maastrichtian pelagic biomicrite is characterized by unsorted pelagic intraclasts floating within the pelagic matrix, and both components only contain Maastrichtian planktonic foraminifera.The floatstone is overlain by another <0.5 m thick intraclastic-bioclastic floatstone characterized by rounded pelagic intraclasts (plasticlasts) containing Maastrichtian planktonic foraminifera floating in the pelagic matrix. The matrix of the later floatstone contains Maastrichtian and Palaeocene planktonic foraminifera mixed together. Thus, the transition from the Maastrichtian to the Palaeocene is not continuous but is characterized by amalgamated debrites that are related to at least two separated re-depositional events within the basin. The overlying pure pelagic biomicrite is rich in planktonic foraminifera that indicates the Palaeocene P3 Zone. A few metres apart, after the covered interval, there are also Eocene pelagic biomicrites with planktonic foraminifera which indicate the Eocene E9 Zone, characterized by the co-appearance of benthic foraminifera (Discocyclina) floating within the pelagic matrix. It is assumed that a Maastrichtian opening of the deep-water environment connected to the Adriatic Basin within the former Adriatic Carbonate Platform west of the island of Vis could be related to a re-activation of an inherited transverse fault zone.

Transfer zones and associated volcanic province in the eastern Valencia Basin: Evidence for a hot rifted margin?

The role of NW-SE transfer zones during the opening of the Northwestern Mediterranean Basin has long been evidenced, mostly from seismic-reflection and magnetic data. Each of these features corresponds to transverse basement steps and/or fractures controlling the progressive deepening from the Valencia Basin toward the center of the Liguro-Provençal Basin. The most important one, the North-Balearic-Fracture-Zone, accounts for the counterclockwise rotation of the Corsica-Sardinia block and separates the Valencia continental basin from the Liguro-Provençal oceanic basin. Another transfer zone, the Central Fracture Zone is the limit of the NE part of the Valencia Basin floored with volcanic basement. Further north, the Catalan Fracture Zone corresponds to a large scale transfer zone that limits between the eastern Pyrenees and the thinned crust of the Gulf of Lion. New observations on deep seismic lines show in detail the extent of a 1–3 km thick volcanic Province around the North-Balearic-Fracture-Zone. It includes the numerous volcanoes of the Valencia Basin mostly superimposed on the transverse fractures zones. The transfer zones are also characterized by narrow syn-rift grabens interpreted as transtensional pull-apart basins along the transfer faults. The transfer zones are associated at depth with domes uplifting the Moho, thinning locally the crust down to 3 km and exhuming deeper material. Deep reflections and thinning at the base of the crust draw extensional shear-zones and crustal boudins that, together with the large amount of syn-rift volcanism in the area, suggests a ductile behavior during early stage of extension. This ductile behavior has then evolved toward more brittle deformation and deposition of syn-rift sediments in asymmetric basins. The volcanic Province disappears in the distal prolongation of the Catalan Fracture Zone that we observe and characterize for the first time. Here a thin crust with flat top consists of westward-dipping reflections in the upper part, rooted in reflective layers. This crust passes laterally to the type II exhumed domain of the Liguro-Provençal Basin and to the oceanic domain to the south. Three crustal domains can thus be distinguished in the transition between the Valencia and Liguro-Provençal Basins illustrating the complex 3D deformation of the area.

Himalayan cross faults affect thrust sheet geometry: An example from the Munsiari thrust sheet near the Gish Transverse fault zone, frontal Darjiling Himalaya, India

The Munsiari thrust (MT) sheet is a dominant thrust sheet in the Himalaya and forms the frontal ridge in the Gorubathan recess of the Darjiling Himalaya. The geometry of the MT sheet in the recess was poorly constrained thereby inhibiting the understanding of how the geometry and kinematics of the sheet varied from the Nepal to the Bhutan Himalaya. We present new structural data and infer the deformation mechanisms and the geometry of the MT sheet in the Gorubathan recess in the Darjiling Himalaya to fill this knowledge gap. The MT sheet was dominated by large-scale, overturned antiforms and synforms. The entire MT sheet was later folded to a north-easterly plunging synformal fold with NE-SW axial trend due to the effect of a Himalayan cross fault in the region named the Gish Transverse fault. A new brittle, out-of-sequence and neotectonically active, Phaparkheti thrust, was recognized in the MT sheet. Deformation microstructures indicate that the temperature of deformation in the MT fault zone and the sheet was ~500 °C to 700 °C and ~400 °C, respectively. Our approach of first mapping major and minor structures and then integrating these studies with deformation microstructure and tectonic geomorphology data resulted in an improved understanding of the structural characteristics of the MT sheet in the Darjiling Himalaya. Our study also suggests that there is considerable variation in the geometry and kinematics of frontal thrust sheets along the Himalayan arc that must be studied systematically in the context of Himalayan salients and recesses.

Role of structural inheritance and salt tectonics in the formation of pseudosymmetric continental rifts on the european margin of the hyperextended Mauléon basin (Early Cretaceous Arzacq and Tartas Basins)

Arzacq and Tartas were two Cretaceous basins developing in the Bay of Biscay as secondary depocentres in the larger Aquitaine Basin. They belong to an Albian rift system, where recent studies have stressed the role of simple-shear thinning on the genesis of regional asymmetric basins. However, the two basins differ from recent models in having a pseudo-symmetric morphology. Here, we address the Early Cretaceous tectono-sedimentary evolution of the Arzacq and Tartas rift basins and the lithospheric processes associated with their genesis. These basins did not suffer major brittle deformation during rifting stage, but nevertheless record a major change in their configuration between the Aptian and the Albian. The Arzacq Basin shifted from a symmetric to a slightly asymmetric configuration. This change was controlled by gravity sliding of the pre-rift sedimentary cover in the eastern Arzacq Basin moving its depocenter south, and by salt diapirism in the western Arzacq Basin moving its depocenter north. Several inherited Paleozoic structures were reactivated as transfer zones and appear to be responsible for this depocenter shift, the emplacement of salt diapirs, at same time regionally limiting gravity sliding. The Tartas Basin maintained a symmetric regime throughout the Early Cretaceous, except along the Barlanès transfer zone where the Lussagnet salt diapir originated. Two drivers of subsidence are thus envisaged in the Arzacq Basin: a Neocomian-Aptian crustal thinning stage, followed by reactivation of Paleozoic faults in Albian time accompanied by salt diapirism and gravity cover sliding. The Mauléon North Pyrenean Basin and its north adjacent Tartas and Arzacq basins thus formed part of a series of rift basins that progressed in maturity southward, from a simple sag basin (Tartas) to a slightly asymmetric basin (aborted detachment, Arzacq) to a hyperthinned basin (Mauléon). Our results offer new insights on the role of: (1) structural inheritance in partitioning extensional strain, (2) transfer zones as able to influence the sedimentary record of basins during crustal thinning, and (3) pre-rift salt décollements as able to separate the structural styles of sub- and supra-salt successions. • Pseudo-symmetric rift basins resulting from Early Cretaceous hyperextension. • Barremian-Aptian sag basins, decoupled deformation between upper and lower crust. • Albian-Cenomanian asymmetric rifting stage. • Synrift salt tectonic and basinward cover gliding along Jurassic salt décollement. • Role of inherited transverse transfer zones during rift formation.

Active crustal deformation and rotations in the southwestern Balkans from continuous GPS measurements

The western limb of the Hellenic Arc defines the boundary of a large intracontinental active extensional domain covering the Aegean and the southwestern part of the Balkan peninsula. Along this boundary a transition from collision in the north to subduction in the south is associated with post-Miocene clockwise rotations of ∼50∘. We present a new GPS velocity field that, with new permanent station velocities in Albania, Bulgaria, Kosovo, Montenegro, and Northern Macedonia, provides insights into previously unresolved aspects on the large-scale dynamics of continental lithosphere and on the relation between long and short-term kinematics. In particular we address (1) the kinematic description of the collision/subduction transition, (2) the relation between long-term finite rotations with geodetically-measured instantaneous rotations, (3) the forces maintaining and resisting the deformation of the extensional domain and (4) the extent of its northern boundary. We use the analogy of rigid elongate inclusions in the velocity field to predict the senses and approximate rates of rotation of crustal blocks in the deforming continental region. Across the collision/subduction transition zone a large rotational pattern in the velocity field is found whose spatial pattern and sense of rotation is compatible with the observed paleomagnetic rotations through the occurrence of fault-bounded block rotations. Geodetic observations show that clockwise vertical axis rotation of the western limb of the Hellenic margin is active today, with distribution and rates that are essentially the same as that defined by the paleomagnetic data for the last 5 Ma. The maximum rates of the rotational component of the velocity field is found along the wide arrangement of fault-bounded blocks in central Greece that accomodate the NE-SW dextral shear transferred from the northern Aegan trough. The northern limit of the rotating margin defines a hinge (Scutari-Pec transverse zone) that has remained stationary throughout the Middle Miocene (relative to the upper plate of the collision/subduction system) with important implications for the distribution of strength of the western margin of the Hellenic Arc. The distribution and style of deformation along the western boundary of the extensional domain is controlled by the relation between gravitational forces, driving the flow of crustal material towards the low-lying adjacent regions sea floor, and heterogeneous resistive forces along the collision/subduction boundary.

Can Certain Actions in Virtual Space Make a Human Being Impatient?

Summary: In 2005, Research Centre for the Study and Observation of Living Conditions noted that 62% of Internet users are trying to save time in preparing for their purchase. It is now 89% for online buyers [1]. In 2018, a survey carried out for the management of the Lemonde.fr site measured that after five seconds of waiting, out of ten potential readers behind the screen, three abandon [2]. According to the Baromil survey from 2018, because the information is available in real time, we are constantly connected in real time. Google, the most used search engine, does not even take 1 second to display thousands of results for our query, whatever it may be [3]. According to Jean Cottraux, psychiatrist and psychotherapist, we are faced with “a society that pushes buttons. We are constantly waiting for an immediate response” [4]. These few examples and with regard to my own research work on Behavioural Differentiations between the Real and the Virtual, my theories on “Avatarization”, the “Transverse Zone” and the “Virtual Intelligence”, developed in my scientific article and my books, impatience seems to have increased due to the use of the connected tool [5,6]. Behaviours have changed from that. These behaviors can also be reproduced in the real world. What about impatience? How is it characterized in the real and virtual?

Effect of forged substrate geometry on temperature and stress field in additive manufacturing

The forming technology compounding forging and additive manufacturing (AM) is a new approach to fabricate partial structures by AM based on forged substrates. Such technology has great potential for improving material utilization and manufacturing efficiency. Using this technology, three three-dimensional transient-coupled thermomechanical finite element models were developed in this study. The models comprised single-pass multilayer walls deposited on three different types of forged substrates, i.e., with a groove, platform, and boss. The temperature and residual stress of the components were measured by an infrared camera and X-ray diffraction, respectively, and the simulated results were found to be consistent with the experimental results. Based on this, the effects of forged substrate geometry on the temperature field and stress field in the laser solid forming process of a Ti-6Al-4 V alloy were investigated. It was found that during the AM process, there was little difference in the molten pool maximum temperature and range of high temperature region for the components fabricated using AM based on forged substrates with different geometries. In addition, the temperature gradient decreased with an increasing number of deposited layers. The component fabricated with a groove had the largest temperature gradient in the early depositional stage, whereas the component with a platform had the lowest residual tensile stress. The higher the bonding zone between the forged substrate and AM part, the higher the longitudinal and transverse main tensile stress zone, and the normal tensile stress was concentrated at the wall corners. The residual stress of the components using reciprocating scanning was much lower than that using single-direction scanning.

Orogen-transverse structures in the eastern Himalaya: Dextral Riedel shear along the Main Boundary Thrust in the Garu-Gensi area (Arunachal Pradesh, India), implication in hydrocarbon geoscience

Abstract Structural mapping and analyses reveal deformation in the rocks of the Lesser Himalayan Miri and Gondwana, and Lower Siwalik Dafla successions across the Miri Thrust (MT) and the Main Boundary Thrust (MBT) in the Garu-Gensi area (Arunachal Himalaya, India). The-north-dipping Gondwana sequence is sandwiched between the Miri Group of rocks in the north and the Lower Siwalik Dafla sandstones in the south. The Gondwana rocks folded four times (D1-D4). Detail outcrop mapping and structural analyses substantiated by satellite images elucidate that the Miri, the Gondwana and the Lower Siwalik rock sequences in the area are traversed by two sets of NW and NE trending cross-fault zones with~70–100 m thickness mappable for ~70 km. The cross-faults trend NW around the locality Daring, while in the western part around Gensi, they trend NE. The westernmost fault slipped dextrally and the easternmost one at Daring sinistrally. These transverse faults offset the MBT: 0.52–0.59 km for the western- and 0.58–1.41 km for the eastern faults. The deformation in the Gondwana sequence may be constrained as syn-Himalayan (i.e., India-Asia collisional event). This was followed by a compression from E/ESE due to the post-Eocene Indo-Burmese collision. The culminating phase of combined India-Asia and Indo-Burmese compression is manifested in field with a strong NE-directed compression with dextral Reidal shear developing in the transverse conjugate fault zones in the area with maximum displacement towards SE. Cluster of the earthquake data indicates record of the events (M ≥ 6) within 30–80 km depth-both N and S of the MBT in the study area. Further, the southerly continuation of the transverse faults below the alluvium can provide vital clue in studying the potential hydrocarbon trap in the northern fringe of the Brahmaputra river.

New U-Pb (SHRIMP) and first Hf isotope constraints on the Tonian (1000-920 Ma) Cariris Velhos event, Borborema Province, NE Brazil

Abstract Orthogneisses associated with metavolcanosedimentary successions related to the 1000 - 920 Ma Cariris Velhos event occur mainly in a ca. 700 km-long sigmoidal-shaped belt that crosscuts the Transversal Zone of the Borborema Province and extends to the fold belts located in its southern or external zone (part of the Riacho do Pontal and Sergipano orogens). Despite its importance, the tectonic setting and the role of those rocks in the geological evolution of the Borborema Province are contentious and not yet well understood. New zircon U-Pb SHRIMP data on an augen-gneiss sill of the Afeicao Suite intruding mica-schists mapped as part of the Santa Filomena Complex yielded a Concordia Age of 974 ± 11 Ma, indicating that at least part of the metasedimentary rocks in the internal zone of the Riacho do Pontal Orogen are Tonian or older and possibly related to the Cariris Velhos event. Hf-in-zircon isotope data are presented for the first time for Cariris Velhos-related ortho-derived rocks of the Afeicao Suite. Analyzed samples yielded eHf(t) in a narrow range between -1.51 and +2.41, with associated TDMHf of 1.6-1.4 Ga, similar to previously obtained Nd isotope data with eNd(t) = -1.0 to +3.1 and TDMNd of 1.5-1.2 Ga. A possible scenario to explain both the geochemical features and the moderately juvenile to slightly evolved, near-chondritic Hf and Nd isotope signatures is a continental arc setting, where fractionated melts produced in the supra-subduction zone mantle wedge carrying a Tonian juvenile signature became contaminated with discrete amounts of Archean-Paleoproterozoic continental crust during ascent, producing Mesoproterozoic model ages which represent the mixture of those two end-members.

Mapping the internal structures of fault zones of the sedimentary cover: a tectonophysical approach applied to interpret TDEM data (Kovykta gas condensate field)

The article presents the results of studying the internal structures of platform fault zones with the use of a new tectonophysical approach to processing and interpretation of electrical exploration data obtained by the transient elec‐ tromagnetic method in the near field zone (TEM). In the study of the central part of the Kovykta gas condensate field (East Siberia, Russia), we applied the ideas of tectonophysics envisaging three stages of fault formation, which determine the three‐membered transverse zoning of a fully formed fault zone. Each subzone is characterized by a certain level of rock disturbance and corresponding electrical conductivity. Based on the analysis of electrical conductivity values, the boundaries can be determined between locations differing by the degrees of rock disturbance of the sedimentary stra‐ tum. Using a map of this parameter, it becomes possible to generally establish the boundaries of fault zones and specify internal subzones. The new approach was applied to assess the electrical conductivity of the reservoirs of the Kovykta field. It is established that there are several zones of faulting in the sedimentary stratum, which have not reached a final stage of development when a single fault plane is formed. Currently, these are zones of increased fracturing and dense occurrence of second‐order ruptures that are typical of platform settings due to their relatively weak tectonic activity. The zones are structurally non‐uniform, as evidenced by rheological layering of the sedimentary cover in the vertical cross‐section. A 3D electrical conductivity model of the largest fault zone in the study area shows alternating segments with more or less developed internal structures. Such segments are confined to layers that differ with respect to frac‐ turing. Exploration and development of hydrocarbon deposits can benefit from 3D modeling of large fault zones with the use of the tectonophysical approach for processing and interpretation of the TEM data. The models can provide addition‐ al arguments for improved decision making about locations for trouble‐free well drilling, as well as for selecting more effective methods for drilling sedimentary strata composed of complex horizontal layers.

Estimation of near-surface attenuation in the tectonically complex contact area of the northwestern External Dinarides and the Adriatic foreland

Abstract. Seismically induced ground motion at a site is generally influenced by the seismic source, the propagation path and the local site conditions. Over the last several decades, researchers have consistently asserted that for near-site attenuation, the spectral parameter κ is subject primarily to the site conditions. In this research, we estimated the parameter κ based on the acceleration amplitude spectrum of shear waves from local earthquakes recorded by seismological stations situated in the western part of Croatia from the slope of the high-frequency part. The spatial distribution of κ values is comparable with seismological, geophysical and geological features, with the published coda-Q values for each station as well as with the isoseismal maps for selected stronger earthquakes in the study area. The complex pattern of longitudinal and transversal major late-orogenic fault zones dissecting early-orogenic thin-skinned tectonic cover in the Kvarner area and the shallow depth to the Moho (Mohorovičić discontinuity) in the Adriatic foreland (southern Istria) are probably responsible for a significant part of wave attenuation and for the anisotropy of attenuation. Regional near-surface attenuation distribution and modelled macroseismic fields point to the conclusion that attenuation properties of rocks in the northwestern External Dinarides are far from isotropic, and the most likely anisotropy sources are the preferential orientations of cracks and fractures under the local tectonic stress field, trapping of waves along major faults (waveguides), and/or attenuation within the fault zones. These results are important for gaining further insight into the attenuation of near-surface crust layers in the northwestern External Dinarides and the associated Adriatic foreland as well as in similar geotectonic settings.

ЗОНУВАННЯ ТРИВИМІРНОЇ МАТРИЦІ УПРАВЛІННЯ ЗМІНАМИ РЕГУЛЯТОРНОЇ ПОЛІТИКИ РОЗВИТКУ НАЦІОНАЛЬНОЇ ЕКОНОМІКИ

The article attempts to work out the relevant methodology that will allow an integrated approach to find solutions to current economic challenges, given the fact that the national economy is a complex multicomponent system. It is emphasized that mathematical methods and models are widely used as effective tools to handle a range of problems in various areas of research and, in particular, in economic studies. However, despite the availability of numerous research endeavors, the issues of modelling the relationships between national economic development and regulatory policy have not been sufficiently studied. The purpose of this study is to build a three-dimensional matrix of regulatory change management in the frameworks of the national economic development. The methodological research background relies on modelling of regulatory policy effects on national economic development by using economic mathematical methods and models. A three-dimensional matrix of managing change in regulatory policy has been proposed which is based on the assessment of the current state of regulatory policy and modelling of the relationships between national economic development and regulatory policy with regard to the obtained values of the aggregate development index calculated by sectors of the national economy, generalized index of the regulatory policy in industries and the indicator of the regulatory policy effects on development, the zoning of which allows to distribute its impact sector by sector along with identifying the nature and the priority areas for further regulatory actions to be applied to a particular industry or sector of the economy. The three-dimensional matrix zoning has been performed according to certain parameters: vertical zoning (zones of passive and active changes), transverse horizontal zoning (zone of fixation and transformation) and horizontal longitudinal zoning (zones adjustment and protection). It is argued that economic mathematical modelling is an important tool in managing business processes. Modelling is used to build reliability models with reference to aggregated development indices by sectors of the national economy and the generalized indices of regulatory policy, and identify specific regulatory policy changes needed to enhance the national economic development.

On petrogeochemical zoning of mesozoic volcanites of the ore fields of gold and polymetallic deposits of the Eastern Transbaikalia

Transverse petrogeochemical zoning in the location of volcanites of Shadaronsky (J2-3) and Mulinsky (J2-3) series, characteristic of volcanic arcs, has been revealed in the Eastern Transbaikalia. Volcanites of the tholeiitic and calc-alkaline series are developed in the frontal zone of the volcanic arc, in the suture zone of the Mongolo-Okhotsk suture (MOS), in the rear zone of the MOS - volcanites of the calc-alkaline series. The volcanites of the frontal and rear parts differ in their petrogeochemical composition, in the degree of oxidation of iron and in the distribution of rare earth elements (REE). These differences are characteristic of the volcanic arcs of the transition zones from the ocean to the continent. Vulcano-plutonic structures of the frontal zone of MOS produce gold mineralization, the rear zone of MOS - polymetallic mineralization.

The development of zones of active plasticity during mode I steady-state crack growth in thin aluminum sheets

Cracks grow in millimeter-scale, ductile metal sheets when a transverse neck fracture process zone fails by microvoid coalescence. Here we showed that the crack growth mechanism changed to a different steady-state process when sheet thicknesses were ⪅100 μm. We experimentally quantified the shape, extent, and evolution of the process zones in 1235 Al and showed that three zones were operating: A large, uncontained plastic zone (PZ) ahead of the crack tip had an embedded, steady-state zone of active plasticity (ZAP) that surrounded a transverse neck fracture process zone (FPZ) which failed via a microvoid-free shear mechanism.

Petrogeochemical Zoning of Mesozoic Volcanic Rocks of the Ore Fields of Gold and Polymetallic Deposits of Eastern Transbaikalia

Transverse petrogeochemical zoning in the location of volcanites of Shadaronsky (J 2-3 ) and Mulinsky (J 2-3 ) series, characteristic of volcanic arcs, has been revealed in the Eastern Transbaikalia. Volcanites of the tholeiitic and calc-alkaline series are developed in the frontal zone of the volcanic arc, in the suture zone of the Mongolo-Okhotsk suture (MOS), in the rear zone of the MOS - volcanites of the calc-alkaline series. The volcanites of the frontal and rear parts differ in their petrogeochemical composition, in the degree of oxidation of iron and in the distribution of rare earth elements (REE). These differences are characteristic of the volcanic arcs of the transition zones from the ocean to the continent. Vulcano-plutonic structures of the frontal zone of MOS produce gold mineralization, the rear zone of MOS - polymetallic mineralization.

Superterreno Pernambuco-Alagoas (PEAL) na Província Borborema: ensaio de regionalização tectônica

O Superterreno Pernambuco Alagoas (PEAL), previamente designado de Maciço e/ou Terreno, é o segmento tectônico identificado imediatamente ao sul do lineamento Pernambuco. Apresenta uma área de cerca de 60.000km2, forma triangular, com a base entre o Recife e imediações de Maceió, e com vértice nas imediações de Santa Cruz, oeste de Pernambuco. Sua composição é extremamente variada, com terrenos de alto grau, arqueanos, paleoproterozoicos, eo-neoproterozoicos e tratos metavulcanossedimentares neoproterozoicos (faixas supracrustais). Estes terrenos são cortados por granitoides neoproterozoicos diversos, incluindo batólitos lineares de grandes dimensões, por stocks e batólitos menores relativamente isolados. Localmente, na sua parte centro sudoeste, foi recentemente reconhecido magmatismo granítico de arco (Ediacarano em idade). O comportamento geotectônico deste amplo superterreno- posicionado entre as faixas orogênicas da Zona Transversal e aquelas da periferia norte do craton do São Francisco (parte do o chamado “domínio meridional” da Borborema) tem sido bastante estudado, discutido e nomeado, mas é de conhecimento geral ainda perfuntório. Apresenta uma trama litoestrutural complexa, e pode ser preliminarmente dividido, para fins expositivos em três porções distintas: porção ocidental (com muitos relictos arqueanos e paleoproterozoicos), porção central (embasamento paleoproterozóico retrabalhado e supracrustais neoproterozoicas) e porção mais oriental, com exposição de um longo e linear batólito longitudinal (longitudinal à costa atlântica) e algumas supracrustais, distintas daquelas anteriormente citadas.

Using the receiver function for studying earth deep structure in the Southern Borborema Province

The Borborema Province is characterized by a succession of tectonic events, including compressive periods associated with amalgamation of lithospheric blocks during the Brasiliano orogeny in the Neoproterozoic, superimposed by extension events related to the breaking of the continents and the South Atlantic formation in the Cretaceous. Ten seismographic broadband stations belonging to the Geoterm Network were installed in the Transversal Zone and South Domains to collect the data used in this work in the southern Borborema Province, northeastern Brazil. Thus, this study aims to determine the thickness of the Moho and Mid-Crustal (“Conrad”) discontinuities and estimate the Vp/Vs ratios to define rock composition using the receiver function over a time window, using the HK-stacking method. The station in the Alto Moxotó Terrain determined a crustal thickness of 35.4 km. The two stations in the Pernambuco-Alagoas Terrain estimated thickness of approximately 37 km and no thinning trend in the geotectonic context. The four stations in the Sergipano Folding Belt indicated thickness ranging between 34.6 and 37.2 km, and a South-North crustal thickening. Mid-crustal discontinuity depth estimates ranged between 10 and 19 km, indicating a WNW-ESE thinning of the upper crust in the middle of the area. The P and S wave velocity ratios appeared to have no geological or tectonic correlation and ranged between 1.68 and 1.77, indicating that the crustal composition is predominantly felsic.

The evolution from an unsteady to a steady mixing zone between two groundwater flow systems with different concentrations

Heat and mass transport through porous media is governed by the advection-dispersion equation. Near the forward moving mixing front the longitudinal and transversal dispersion lengths are non-zero; only dispersion by molecular diffusion remains. The present paper presents mathematical-physical arguments why in steady transport the dispersion lengths are equal to zero. In conventional models the dispersion lengths are generally assumed to be process-independent. To interpolate between the relatively large dispersion lengths near time-dependent moving front and the steady transport conditions far away from the front, a mathematical model is proposed to describe the process-dependent time-evolution of the dispersion lengths. In this model, the dispersion lengths near the forward moving front are equal to the well-established conventional dispersion lengths that correctly represent the mixing near the front. However, further behind the moving front, where the mass transport has become (almost) steady, the process-dependent model results in vanishing dispersion lengths and, consequently, in a substantially smaller transversal mixing zone.

Role of transverse structures in paleoseismicity and drainage rearrangement in rift systems: the case of the Valdecebro fault zone (Teruel graben, eastern Spain)

The E–W trending, nearly pure extensional Valdecebro fault zone is a transverse structure at the central sector of the N–S Teruel graben. It was activated by the Late Ruscinian (Early Pliocene, ca. 3.7 Ma), giving rise to structural rearrangement of the graben margin. Until the Late Pleistocene, it has accommodated a net slip ca. 205 m, with slip rate of 0.055 mm/a. Paleoseismicity has been analysed in a 29-m-long, 5-m-deep trench excavated through a fault branch that offsets a Pleistocene pediment surface. The paleoseismic succession includes a minimum of 6–7 events occurred since ca. 142 ka BP, although a model with 12 events could be more realistic. The following paleoseismic parameters have been inferred, assuming a minimum of 6 and a maximum of 12 events: average coseismic slip = 58–117 cm; recurrence period = 8.4–28.4 ka; potential moment magnitude Mw = 5.8–5.9. The recorded displacement since ca. 142 ka BP totalizes 7.0 m, with slip rate of 0.05–0.07 mm/a. Slip on the transverse Valdecebro fault zone has critically contributed to bulk deformation under a prevailing ‘multidirectional’ extensional regime. Drainage patterns have been rearranged, recurrently switching between westward and southward directions as a consequence of diverse slip episodes at the Valdecebro fault zone (E–W) and the neighbouring La Hita (N–S) and Concud (NW–SE) faults. The ultimate westward drainage of the Valdecebro depression incised and dismantled a southward-sloping Pleistocene pediment sourced at the Valdecebro mountain front, representing a capture by the Alfambra river occurred between 124 and 22 ka BP.

Transverse Faults of the Eastern Caucasus and Their Manifestations in Seismicity

The features of the spatial distribution of earthquake sources in the eastern Caucasus (within the borders of Azerbaijan and the Chechen Republic of the Russian Federation) are analyzed. According to the method developed in recent years to identify seismogenic zones of deep faults by manifestations of weak seismicity, transverse faults extending in the diagonal direction (SW−NE) are found. Like other faults that are longitudinal to the strike of the mountain-folded structures of the greater Caucasus, they are characterized by the different level of seismic activity at the different segments. Only their separate segments of short length are seismically active. Transverse faults are deep and intersect the Earth’s crust through all its thickness. Some of them are associated with the sources of destructive earthquakes. For example, the Kurchaloi earthquake with M = 5.6 occurred on the northern slope of the greater Caucasus, in the eastern part of the Chechen Republic in 2008, which caused human losses and destructions. Its source was confined to the deep NE-striking fault, confining the mountain protrusion of the Dagestan wedge from the northwest. The strong seismic events Anapa of 1996 and Lower Kuban’-II of 2002 also took place on the western periclinal of the greater Caucasus, in the area of Anapa transverse flexural-fault zone. The longitudinal tectonic faults (of Caucasus strike) also demonstrate not only weak but also high magnitude seismicity. Such faults were associated with the sources of the strongest earthquakes in the late 20th and early 21st centuries (1970 Dagestan, 1977 Chernogorsk, 1991 Racha, 1992 Barisakho, 2000 Baku, and 2009 Oni). But the transcaucasian disjunctives for a long time have been underestimated as hazardous seismogenic structures, although their activation may lead to serious consequences. This work shows the role of such faults in the distribution of strong and weak seismicity of the region.