Morphostructural Analysis Research Articles

Semiautomatic construction of isobase surfaces: A case study from the central Western Carpathians

This article describes a method for semiautomated construction of isobase surfaces in the environment of a Geomorphological Information System (GmIS). The motivation to automate the process is that the manual construction of isobase surfaces involves several decision procedures, and also a lot of manual vectorization which can be time-consuming if the area of interest is large.A (semi-)automated process of isobase surface construction could accelerate the process of morphostructural analysis. Therefore, the contribution focuses on design, development and testing of such a method. The developed tools were compared to an expert driven construction of isobase surfaces. The automatically constructed data layers were compared to the layers that were constructed manually in the southwest part of the study area (Turčianska kotlina basin (Western Carpathians) and surrounding area in Slovakia). Three different statistical methods were used (correlation, linear regression and DTM volume difference checking). All three methods proved very high similarity of automatically created isobase surfaces to expert driven isobase surfaces creation. The results show that the method of semiautomated creation can be used in morphostructure analysis and save the time needed for manual isobase surface creation.The method's technological background is based on the ESRI platform. The original desktop solution has been developed for use on a client/server architecture that is able to present the capabilities of GmIS to a wider geomorphological audience.

Morpho-structural analysis of Harrat Al Sham volcanic field Arabian plate (Syria, Jordan, and Saudi Arabia): methodology and application

We present here a digital methodology aimed at identifying the morphometry of monogenic volcanic cones including edifice height, slope angle, and volume. We recognize more than 800 monogenic volcanic cones from the Harrat Ash Shaam volcanic province (HASV, northern Arabian Plate) to the north of the Arabian plate by using Landsat7 Enhanced Thematic Mapper plus and digital elevation models (Shuttle Radar Topography Mission, SRTM data). Our results show that the volcanic cones fall into six clusters, each one having a NW-SE orientation parallel to the Red Sea rifting. The density of the cones is most likely controlled by fissure distribution and a possible rotation in the HASV lithospheric block, rather than by the age of the volcanic activity. Interaction with crustal lithologies also plays a negligible role during magma migration. However, the morphology of the monogenic volcanic cones appears to be significantly modified by erosion processes, and both the height and slope of the various cones thus can be used to estimate their relative ages. From such morphological criteria, HASV monogenetic volcanoes in Jordan and Saudi Arabia are older than those in the Golan Heights and the Jabal Al Arab Mountain in Syria, thus, supporting the hypothesis of a northward migration of the recent explosive activity. Our new data, together with the available sediment thickness data, give rise to a new volcano-tectonic interpretation. We show that variations in the cumulative volume of monogenic volcanic cones in several zones of the study area can be related with the sediment thickness (basement depth), and therefore, we propose that the sediment thickness most likely affects the properties of magma before eruption. The reactivation of a deep previous fault perhaps also explains the higher volume of monogenic volcanic cones, focused along a well-defined alignment. This study, thus, gives insight into the relations between sediment thickness, the volcanism, and tectonics. Our results based on new digital treatment of remote sensing data are in overall good agreement with the volcano-tectonic evolution of HASV. This allows us to recommend this methodology as a potential tool to study volcanic cones of other inaccessible regions, either on Earth or other terrestrial planets.

Morphostructural analysis and Cenozoic evolution of Elephant Island, Southern Scotia Arc, Antarctica

Elephant Island, located in the vicinity of the present-day active boundary of the South Shetland Block and the Antarctic and Scotia plates, is a region of particular interest for understanding the past and present geodynamic evolution of the southern Scotia Arc. Lineament from different data sources, field-measured fractures and geomorphological evidences have been analysed in this context. The lineaments extracted from aerial photographs (1,624), from a DEM (348) and from RADARSAT-2 satellite data (1,365) indicate four dominant lineament sets with NE–SW, NW–SE, N–S and W–E strikes. All data sources identified similar lineament families, but differences in the frequency distributions and subsequently on the dominant orientations were observed. The measurements direct of fractures were obtained from 23 sites in the field at which 278 planes were measured. Fracture planes indicate main modes trending in the NNE–SSW and NNW–SSE directions and a secondary mode in the E–W. The major trends of the fracture measurements and the lineaments display a good correlation in the E–W direction. However, there is an angular variation in the azimuth values of the NNE–SSE and NNW–SSE fractures with respect to the N–S, NE–SW and NW–SE orientations of the lineaments of approximately 20°. This trend deviation may be due to the fact that mapped lineaments are composed of small fracture sets that may be related to shear fractures that cannot be distinguished at the aerial photograph or radar satellite data scales. Submerged sea-floor morphological feature orientations match the studied morphostructures on the island and the main tectonic structures in this part of the Scotia Arc. A linkage of the main lineament families to the tectonic stages from the Oligocene to the present has been proposed, taking into account the information of the orientation and sense of movement of the fractures and stresses in the Elephant Island region.

Tectonic activity revealed by morphostructural analysis: Development of the Sierra de la Candelaria range, northwestern Argentina

The tectonically active broken foreland of NW Argentina is a recent analog of the eastern margin of the Puna plateau during Mio-Pliocene times and likely of other broken forelands worldwide. In order to evaluate active tectonism in the broken foreland of the NW Argentine Andes, we examined the complex geomorphology in the vicinity of the basement-cored Sierra de la Candelaria range at ∼26°S and deciphered multiple episodes of crustal deformation spanning the Pliocene to the Quaternary. Digital elevation models, satellite images and geological data within a GIS environment allowed us to analyze the terrain, drainage networks, river dynamics and structure, as well as to obtain detailed geomorphological mapping, active tectonic indices, longitudinal river profiles and structural sections. Three morphostructural segments were defined based on the structural features, the differential vertical dissection pattern over the basement, the faulted Pliocene to recent deposits, the stepwise propagation of anticlines and the distortion over the fluvial system. By combining the several lines of evidence, we concluded that the Sierra de la Candelaria range was subjected to a multi-stage development. The first stage uplifted the central segment concomitant with the formation of the surrounding ranges and with the main partition phase of the foreland. After a significant time lapse, the mountain range was subjected to southward thick-skinned growth and northward growth via stepwise thin-skinned deformation and exerted control over the dynamics of the Río Rosario. Taking into account the surrounding basins and ranges of the Sierra de la Candelaria, the southern Santa Bárbara System is characterized by partially isolated intramontane basins (Choromoro and Rosario) limited by shielded ranges that caused moisture block and shows continuous deformation. These features were related to early stages of a broken foreland evolution model and modern analogs were found at the northern Santa Bárbara System, in the vicinity of the Siancas/Güemes Valley or at the more evolved stage represented by the Lerma Valley. In addition, ancient analogs were defined for the Humahuaca basin conditions at 4–3 Ma ago or for the Toro basin at 6–3 Ma, among others.

The relationship between the lineaments and tectonics of the Kandalaksha Gulf in the White Sea

The regularities of the evolution of the lineaments and weakened zones within the water area and coasts of the Kandalaksha Gulf are considered. Morphostructural analysis of the territory is made and the radial diagrams of lineaments in different parts of the study area are compared. An attempt to connect the structure of the lineament system in the study area with the tectonic evolution of the major regional structure, viz., the Kandalaksha Gulf, is made.

Age constraints and denudation rate of a multistage fault line scarp: an example from Southern Italy

The morphological evolution of a carbonate fault line scarp from southern Italy, generated by transpressional faulting and evolved by slope replacement, has been reconstructed. 14C dating of faulted slope deposits (ages included between 18 ka and ∼8 ka BP) have been performed to constrain the Late Pleistocene — Holocene evolution of that scarp. Long-to short-term denudation rates have been also evaluated for the understanding of the mountain front origin. The slope shows well-defined triangular facets combined with the presence of N-S-striking mountainward-dipping fault planes. The envelope of the slope foot appears slightly curved in a planimetric view and shows an E-W-trending offset in its southern part, making such a feature quite different from the recurrent rectilinear fault scarps, often related to normal faulting. Morphostructural analysis showed that: i) the oldest displacement was generated by a fault with a reverse component of movement; ii) the slope represents an inherited feature, only recently exhumed, and developed starting from a high-angle curved surface; iii) the upper Pleistocene — Holocene extensional faulting has only affected the slope foot and associated waste deposits, causing a series of collateral morphological effects, as fluvial cut of preexisting valleys and the genesis of conspicuous mass movements.

Structural investigations of TiO2–WO3–Au porous composites

In the present study, a morpho-structural analysis of heat treated TiO2–WO3–Au aerogel composites is presented. Simultaneously, the influence of the loaded Au nanoparticles on the morphological and structural characteristics of the TiO2–WO3 aerogel is also analyzed. X-ray diffraction data (XRD) and Raman spectroscopy measurements indicated that TiO2 crystallizes mainly in anatase phase, while the WO3 structure remains amorphous. The morphological features of the samples, i.e. crystallites mean size, particle size distribution, and specific surface area of the pores, are investigated by using XRD, transmission electron microscopy (TEM), and N2 adsorption/desorption, respectively. The results indicate a decrease in size of the titania crystallites as the tungsten oxide content increases. The diffuse reflectance spectra modified by applying a Kubelka–Munk transformation reveal that the presence of gold nanoparticles improves the material’s response in the visible domain.

Geodetic and geological evidence of active tectonics in south-western Sicily (Italy)

Integrated geological, geodetic and marine geophysical data provide evidence of active deformation in south-western Sicily, in an area spatially coincident with the macroseismic zone of the destructive 1968 Belice earthquake sequence. Even though the sequence represents the strongest seismic event recorded in Western Sicily in historical times, focal solutions provided by different authors are inconclusive on possible faulting mechanism, which ranges from thrusting to transpression, and the seismogenic source is still undefined. Interferometric (DInSAR) observations reveal a differential ground motion on a SW–NE alignment between Campobello di Mazara and Castelvetrano (CCA), located just west of the maximum macroseismic sector. In addition, new GPS campaign-mode data acquired across the CCA alignment documents NW–SE contractional strain accumulation. Morphostructural analysis allowed to associate the alignment detected through geodetic measurements with a topographic offset of Pleistocene marine sediments. The on-land data were complemented by new high-resolution marine geophysical surveys, which indicate recent contraction on the offshore extension of the CCA alignment. The discovery of archaeological remains displaced by a thrust fault associated with the alignment provided the first likely surface evidence of coseismic and/or aseismic deformation related to a seismogenic source in the area. Results of the integrated study supports the contention that oblique thrusting and folding in response to NW–SE oriented contraction is still active. Although we are not able to associate the CCA alignment to the 1968 seismic sequence or to the historical earthquakes that destroyed the ancient Greek city of Selinunte, located on the nearby coastline, our result must be incorporated in the seismic hazard evaluation of this densely populated area of Sicily.

Structural setting of the Čertovka landslide (Ústí nad Labem, Czech Republic): morphostructural analysis and electrical resistivity tomography

The Certovka landslide at Vaňov south of Usti nad Labem, Czech Republic, is developed in a steep slope of the Labe River Valley (LRV). A major episode of landsliding occurred in the first months of 1995, and the slope at Vaňov has been subjected to geological and geomorphological investigation since then. This paper presents structural setting of the Certovka landslide based on the latest geological survey, detailed geomorphological mapping, morphostructural analysis and results of electrical resistivity tomography. The landslide was found to be initiated at the boundary between Late Eocene to Oligocene basaltic lavas above and volcaniclastics below, with bedding dipping against the slope (anaclinal slope). The underlying volcaniclastics show tendency to argillization and have a much lower rock strength, which acts as an important factor of slope instability at the site. The Certovka landslide is a complex slope deformation consisting of several landslides and flowslides, with boulder streams merging into a boulder accumulation further downslope. The headscarp area of the landslide developed at one of the structural levels built by basaltic lavas and forming step-like morphology of the valley slope. The headscarp coincides with the course of a regional E–W-striking Vaňov Fault which underwent multiple tectonic history and is associated with a dense fracture system including smooth slickensides on the headscarp. Structural observations combined with detailed knowledge of the anatomy of the landslide based on airborne data, surface data and geophysical data permitted to conclude on structural controls of landsliding and predict future evolution of the slope deformation. Future landsliding will be initiated at structural levels of basaltic rocks, with the headscarps developed along fractures parallel to the Vaňov Fault. The probable gradual retreat of headscarps at the individual structural levels along the slope profile denotes a retrogressive landslide style.

The application of morphostructural analysis and its validation by comparison with documented faults within the Zlate Hory ore district (the northeastern part of the Bohemian Massif)

The application of morphostructural analysis and its validation by comparison with documented faults within the Zlate Hory ore district (the northeastern part of the Bohemian Massif)

The Calama–Olacapato–El Toro fault system in the Puna Plateau, Central Andes: Geodynamic implications and stratovolcanoes emplacement

The structural evolution of the Puna Plateau is characterized by the activity of both orogen-parallel and orogen-oblique faults. Understanding the possible relationship between these two structural styles, their geodynamic implications and the influence on the migration of magmas is important to get insights into the tectonic and magmatic evolution of the Central Andes. In this study, we present a structural analysis of the orogen-oblique Calama–Olacapato–El Toro fault system and the surrounding orogen-parallel thrust faults in the central-eastern Puna Plateau. Morphostructural analysis and field mapping reveal the geometry, kinematics and dynamics of the tectonic features in the studied area. We propose a three-dimensional geometrical reconstruction of the main fault planes showing their attitude and intersections at depth. The study indicates that the crust underwent simultaneous deformation along both the vertical transcurrent Calama–Olacapato–El Toro fault system and the low-angle thrust faults, and that the back-arc portion of the Calama–Olacapato–El Toro fault system developed as a transfer zone among the main N-striking thrusts. Our model considers that both orogen-parallel and orogen-oblique fault systems should be regarded as parts of the same tectonic system, accommodating crustal shortening of a thickened crust. The study suggests that the tectonic control on the magma and fluid circulation in the crust is mainly related to the geometry of the fault planes and the orientation of the stress field, with a previously unrecognized important role played by the orogen-parallel thrust faults on the emplacement of the stratovolcanoes. • A structural analysis of the central-eastern Puna Plateau is presented. • Morphostructural and field data and the 3D geometry of main faults have been obtained. • The Calama–Olacapato–El Toro faults developed as a transfer fault system. • Thrusts and regional transfer faults evolved simultaneously in Late Cenozoic time. • The geometry of the faults and the stress field control the volcanism in the area.

Interblock zones in the crust of the southern regions of East Siberia: tectonophysical interpretation of geological and geophysical data

Interblock zones in the crust of the southern regions of East Siberia: tectonophysical interpretation of geological and geophysical data

Volcano-tectonic evolution of the northern part of the Arabian plate in the light of new K–Ar ages and remote sensing: Harrat Ash Shaam volcanic province (Syria)

The Harrat Ash Shaam volcanic province (HASV) is the largest volcanic field in the Arabian plate. It developed during the Cenozoic close to the southern part of Dead Sea fault system and has been linked to the tectonic evolution of the Red Sea rifting since the early Oligocene. The HASV is an ideal environment to study volcanism adjacent to a strike–slip fault (the Dead Sea fault system) and constrain the development of regional deformation along such lithospheric structures. We here present a morpho-structural analysis based on digital elevation data coupled with remote sensing observations and new K–Ar ages on fresh separated groundmass which allow us to propose a new volcano-tectonic model of the HASV. From Landsat7 Enhanced Thematic Mapper plus (ETM+) and SRTM data, we recognize more than 350 monogenetic volcanic cones grouped in three main clusters. Topographical variations between these clusters are interpreted as reflecting different volcanic phases. The new ages measured here range between 7.13±0.10Ma and 0.056±0.009Ma. Together with previous geochronological data, they reveal two main periods of volcanic activity. The first period lasted from late Oligocene up to early-middle Miocene (26–16Ma), and the second period has been active since 13Ma, indicating a gap of volcanic activity between ~16 and ~13Ma. The volcano-tectonic evolution model suggests two different extensional styles, “en-echelon” rifting during the first period, and counterclockwise rotation during the second one. Alternative to the Afar plume hypothesis, a thinned lithosphere underneath the HASV as supported by geophysical modeling, can explain magma genesis in the northern part of the Arabian plate.

Influence of bedrock structures on the spatial pattern of erosional landforms in small alpine catchments

ABSTRACTStructural settings and lithological characteristics are traditionally assumed to influence the development of erosional landforms, such as gully networks and rock couloirs, in steep mountain rock basins. The structural control of erosion of two small alpine catchments of distinctive rock types is evaluated by comparing the correspondences between the orientations of their gullies and rock couloirs with (1) the sliding orientations of potential slope failures mechanisms, and (2) the orientation of the maximum joint frequency, this latter being considered as the direction exploited primarily by erosion and mass wasting processes. These characteristic orientations can be interpreted as structural weaknesses contributing to the initiation and propagation of erosion. The morphostructural analysis was performed using digital elevation models and field observations. The catchment comprised of magmatic intrusive rocks shows a clear structural control, mostly expressed through potential wedges failure. Such joint configurations have a particular geometry that encourages the development of gullies in hard rock, e.g. through enhanced gravitational and hydrological erosional processes. In the catchment underlain by sedimentary rocks, penetrative joints that act as structural weaknesses seem to be exploited by gullies and rock couloirs. However, the lithological setting and bedding configuration prominently control the development of erosional landforms, and influence not only the local pattern of geomorphic features, but the general morphology of the catchment. The orientations of the maximum joint frequency are clearly associated with the gully network, suggesting that its development is governed by anisotropy in rock strength. These two catchments are typical of bedrock‐dominated basins prone to intense processes of debris supply. This study suggests a quantitative approach for describing the relationship between bedrock jointing and geomorphic features geometry. Incorporation of bedrock structure can be relevant when studying processes governing the transfer of clastic material, for the assessment of sediment yields and in landforms evolution models. Copyright © 2012 John Wiley & Sons, Ltd.

Subsurface structure of the Solfatara volcano (Campi Flegrei caldera, Italy) as deduced from joint seismic‐noise array, volcanological and morphostructural analysis

The joint application of different seismological techniques for seismic noise analysis, and the results of a volcanological and morphostructural survey, have allowed us to obtain a detailed and well constrained image of the shallow crustal structure of the Solfatara volcano (Campi Flegrei caldera, Italy). Horizontal‐to‐vertical spectral ratios, inversion of surface wave dispersion curves and polarization analysis provided resonance frequencies and peak amplitudes, shear wave velocity profiles and polarization pattern of coherent ambient noise. These results, combined in a unique framework, indicate that the volcanic edifice is characterized by lateral and vertical discontinuities and heterogeneities in terms of shear wave velocity, lithological contrasts and structural setting. The interpretation of the seismological results, with the volcanological and morphostructural constraints, supports the hypothesis that the volcano has been characterized by a complex and intense activity, with the alternation of constructive and destructive phases, during which magmatic and phreatomagmatic explosions built a complex tuff‐cone, later reworked by atmospheric agents and altered by hydrothermal activity. The differences in the velocity structure between the central and eastern parts of the crater have been interpreted as resulting from a possible eastward migration of the eruptive vent along the deformational features affecting the area, and to the presence of viscous lava and lithified tuff bodies within the feeding conduits, which are buried under a covering of reworked materials of variable thickness. The observed fault and fracture systems, partially inherited from regional structural setting and exhumed during volcanism and ground deformation episodes also seems to strongly control wave propagation, affecting the noise polarization properties.

Post-Messinian evolution of the Florence Ridge area (Western Cyprus Arc), Part I: Morphostructural analysis

The Florence Ridge, part of the western Cyprus arc, is a compressional relief that was eroded during the Messinian salinity crisis while deposition of salt occurred North (Antalya basin) and South (Herodotus abyssal plain). In order to better assess the impact of salt-tectonics in the Florence Ridge region deformations, we conducted a morpho-structural analysis of available multibeam and seismic data (Simed and Prismed II campaigns). It is indeed a crucial issue to distinguish crustal and gravity driven structures in the compressional to strike-slip belts of the eastern Mediterranean.Along the Antalya basin, we mainly observed multi-directional tectonic rafts typical of gravity gliding above salt. On the Florence Ridge itself, the base of salt evolves laterally to a Messinian erosional surface that erodes a series of stacked nappes. This surface is involved in recent faulting. South of the Florence Ridge, a nearly 100km wide fold belt characterizes the Herodotus abyssal plain. Three different zones parallel to the Florence Ridge appear within this fold belt. Those are respectively from North to South zones A, B and C. Zone A is characterized mainly by small-wavelength folding and faulting. Approaching Zone B, a long extensional graben deforms the seafloor. Zone B stands ~100 to 200m higher than zones A and C. There, salt welding seems common. In the easternmost zone B deep sub-circular bathymetric depressions are associated with extremely thick and fan-shaped depocenters probably emplaced in relation with active sub-salt thrusts. Many evidences suggest post-Messinian uplift in this zone. Zone C shows medium to high wavelength salt-cored folds. Wavelength of those folds increase approaching the distal Nile deep-sea fan. Within zone C, a nearly undeformed domain exists approaching the Eratosthenes seamount. ‘En echelon’ folds bound this flat domain suggesting lateral salt extrusion at the junction between zone C and the distal Nile deep-sea fan.To conclude, numerous evidences argue for a post-Messinian reactivation of the pre-Messinian Florence Ridge accretionary wedge (numerous folds, uplifted zones). The salt, as on the nearby Mediterranean Ridge, decouples deep and surface deformations and even allow the development of isolated grabens and associated salt ridges in the heart of the Florence compressional zone. We propose in this case that local basal slope of salt increase related to basement fault activity triggered gravity gliding and thus extensional deformation despite the regional compressional regime. Finally, this study shows that the eastern Nile deep-sea fan, submitted to extremely vigorous salt tectonics seems to have collided with the Florence Ridge fold belt and to have generated a “salt extrusion” zone.

Neotectonics in the northern equatorial Brazilian margin

Abstract An increasing volume of publications has addressed the role of tectonics in inland areas of northern Brazil during the Neogene and Quaternary, despite its location in a passive margin. Hence, northern South America plate in this time interval might have not been as passive as usually regarded. This proposal needs further support, particularly including field data. In this work, we applied an integrated approach to reveal tectonic structures in Miocene and late Quaternary strata in a coastal area of the Amazonas lowland. The investigation, undertaken in Marajo Island, mouth of the Amazonas River, consisted of shallow sub-surface geophysical data including vertical electric sounding and ground penetrating radar. These methods were combined with morphostructural analysis and sedimentological/stratigraphic data from shallow cores and a few outcrops. The results revealed two stratigraphic units, a lower one with Miocene age, and an upper one of Late Pleistocene-Holocene age. An abundance of faults and folds were recorded in the Miocene deposits and, to a minor extent, in overlying Late Pleistocene-Holocene strata. In addition to characterize these structures, we discuss their origin, considering three potential mechanisms: Andean tectonics, gravity tectonics related to sediment loading in the Amazon Fan, and rifting at the continental margin. Amongst these hypotheses, the most likely is that the faults and folds recorded in Marajo Island reflect tectonics associated with the history of continental rifting that gave rise to the South Atlantic Ocean. This study supports sediment deposition influenced by transpression and transtension associated with strike-slip divergence along the northern Equatorial Brazilian margin in the Miocene and Late Pleistocene-Holocene. This work records tectonic evidence only for the uppermost few ten of meters of this sedimentary succession. However, available geological data indicate a thickness of up to 6 km, which is remarkably thick for an area regarded as a passive margin.

New discoveries of mud volcanoes on the Moroccan Atlantic continental margin (Gulf of Cádiz): morpho-structural characterization

During the MVSEIS-08 cruise of 2008, ten new mud volcanoes (MVs) were discovered on the offshore Moroccan continental margin (Gulf of Cádiz) at water depths between 750 and 1,600 m, using multibeam bathymetry, backscatter imagery, high-resolution seismic and gravity core data. Mud breccias were recovered in all cases, attesting to the nature of extrusion of these cones. The mud volcanoes are located in two fields: the MVSEIS, Moundforce, Pixie, Las Negras, Madrid, Guadix, Almanzor and El Cid MVs in the western Moroccan field, where mud volcanoes have long been suspected but to date not identified, and the Boabdil and Al Gacel MVs in the middle Moroccan field. Three main morphologies were observed: asymmetric, sub-circular and flat-topped cone-shaped types, this being the first report of asymmetric morphologies in the Gulf of Cádiz. Based on morpho-structural analysis, the features are interpreted to result from (1) repeated constructive (expulsion of fluid mud mixtures) and destructive (gravity-induced collapse and submarine landsliding) episodes and (2) interaction with bottom currents.

Middle-Late Pleistocene marine terraces and fault activity in the Sant’Agata di Militello coastal area (north-eastern Sicily)

The coastal sector of Sant’Agata di Militello (north-eastern Sicily) is characterized by a flight of raised Middle-Upper Pleistocene marine terraces occurring at different heights with respect to present sea level. In particular, the geomorphological survey and the analysis of stereo-pairs of aerial photographs allowed to recognize at least five main orders of well preserved Quaternary surfaces and relative deposits mostly located at the hanging wall and at the footwall of the Pleistocene northwest-dipping Capo d’Orlando normal fault, which controlled the geomorphological evolution of the coastal area. The marine terraces show an overall good morphological continuity and are formed by marine platforms overlain by littoral deposits made up of yellow littoral sand and gravels in a sandy matrix. The continental sedimentary cover of the 3rd order terrace contains mammal-bearing deposits that were previously dated 200±40ka BP by isoleucine epimerization method, allowing to relate them to MIS 7.1 high-stand. In order to better define the whole terrace chronology, deposit samples were analyzed by Optically Stimulated Luminescence (OSL) methodology, a conventional SAR protocol used with sand-sized quartz. New datings, together with the detailed morphostructural analysis, allow to relate the 2nd and 4th order terraces to MIS 5.5 and 8.5, respectively, and to reconstruct the tectonic evolution of this coastal area, constraining the activity of the Capo d’Orlando fault.

Morphostructural characterization of soil conventionally tilled with mechanized and animal traction with and without cover crop

The structural stability and restructuring ability of a soil are related to the methods of crop management and soil preparation. A recommended strategy to reduce the effects of soil preparation is to use crop rotation and cover crops that help conserve and restore the soil structure. The aim of this study was to evaluate and quantify the homogeneous morphological units in soil under conventional mechanized tillage and animal traction, as well as to assess the effect on the soil structure of intercropping with jack bean (Canavalia ensiformis L.). Profiles were analyzed in April of 2006, in five counties in the Southern-Central region of Paraná State (Brazil), on family farms producing maize (Zea mays L.), sometimes intercropped with jack bean. The current structures in the crop profile were analyzed using Geographic Information Systems (GIS) and subsequently principal component analysis (PCA) to generate statistics. Morphostructural soil analysis showed a predominance of compact units in areas of high-intensity cultivation under mechanized traction. The cover crop did not improve the structure of the soil with low porosity and compact units that hamper the root system growth. In areas exposed to animal traction, a predominance of cracked units was observed, where roots grew around the clods and along the gaps between them.