Daljinska istraživanja kao preliminarna metoda za otkrivanje aktivnih tektonskih struktura: primjer albanskog orogena

As is well known, both the traditional direct geological and geophysical survey methods used to identify geologic features are very expensive and time-consuming procedures. In this regard, remote sensing methods applied to multispectral and medium spatial resolution satellite images allow a more focused approach with respect to the more specific geologic methods. This is achieved by a preliminary land inspection carried out by the semi-automated analysis of satellite imagery. This avoids wasting resources as the geological/geophysical survey methods can be later applied only to those zones suspected of having certain tectonic activity (derived by the remotely sensed imagery). This paper will evaluate an ASTER sensor satellite image (and its derived Digital Elevation Model or DEM), in order to point out the suspected presence of active geologic structures (faults). The area in question is west – central Albania. The results of the remote sensing procedures are later compared with the established data for the same area taken by satellite images, in order to verify the reliability of the adopted method. The source of the established data has been from the bibliography.Tradicionalne izravne geološke i geofizičke metode istraživanja koje se koriste za prepoznavanje geoloških obilježja su vrlo skupe i dugotrajne. U tom smislu metode daljinskh istraživanja za analizu multispektralnih satelitskih snimaka i snimaka srednje rezolucije omogućuju kvalitetniji pristup s obzirom na specifične geološke metode. U skladu s tim moguće je napraviti preliminarnu analizu površine tla putem poluautomatske analize satelitskih snimaka. Ovakva analiza omogućuje snižavanje troškova na način da se geološke/geofizičke metode istraživanja koriste naknadno, i to u onim područjima za koje se ovakvom analizom (korištenjem daljinskih snimaka) utvrdi postojanje određene tektonske aktivnosti. U ovom radu analizira se satelitska snimka ASTER (i na temelju nje napravljen digitalni model reljefa – DMR) kako bi se uputilo na eventualnu prisutnost aktivnih geoloških struktura (rasjeda). Ovim istraživanjem obuhvaćeno je područje zapadne i središnje Albanije. Radi utvrđivanja pouzdanosti navedene metode rezultati analize snimaka dobivenih daljinskim istraživanjem su uspoređeni s postojećim podacima za isto područje dobivenima satelitskim snimanjem. Postojeći, istraživanjima potvrđeni podaci preuzeti su iz objavljene literature

Seismic imaging of Late Miocene (Messinian) evaporites from Western Mediterranean back-arc basins

An analysis of multichannel seismic reflection data was conducted focusing on the comparison between the Messinian Salinity Crisis (MSC) and Plio-Quaternary (PQ) evolution of the eastern Sardo-Proven\ue7al and northern Algero- Balearic basins and related margins in the West Mediterranean Sea. Both basins were completely opened during the MSC and their well-defined seismic stratigraphy is very similar in the deep parts. The primary difference between these two basins is due to their different pre-MSC extensional history, including the opening age and the stretching factors. These factors influenced the occurrence of post-MSC salt tectonics on these margins

Sabrina Coast (East Antarctica) depositional processes highlightedthrough stratigraphic and paleoenvironmental diatom analysis

The systematic survey of Antarctic margin sedimentary sequences offers, especially in poorly investigated areas,the opportunity to obtain a wide range of information on glacio-eustatic, climatic, and tectonic events. Multi-disciplinary datasets resulting from geophysical surveys and scientific coring and drilling are needed to addressquestions regarding the orbital forcing and the global response of the hydrosphere (oceans and atmosphere),cryosphere, and biosphere. The PNRA Tytan Project, embedded into the Australian project \u201cInteractions of theTotten Glacier with the Southern Ocean through multiple glacial cycles\u201d (Australian National University), aimsto understand how the Totten Glacier behaved during past Holocene and Pleistocene times of warmer climate.Insights for reconstructing the depositional and hydrodynamic environments of the continental margin off theTotten Glacier, a large outlet glacier located on the Sabrina Coast of East Antarctica, are addressed throughmicropaleontological efforts. The micropaleontological research group focused on identification of diatombiostratigraphic markers and assemblage analyses in sediment cores collected from the Sabrina Coast continentalslope during the RV Investigator mission IN2017_V01 in order to reconstruct paleoenvironments and to place ageconstraints on the sedimentary sequences.All but one of the piston cores recovered late Pleistocene sediments, documenting MIS 9 \u2013 MIS 1, withinterglacial intervals characterized by diatomaceous sediments dominated by the open water taxon Fragilariopsiskerguelensis. Glacial intervals have much lower diatom concentrations and a higher proportion of reworked forms.A single piston core, IN2017_V01_PC03, recovered a more complicated sedimentary sequence. This sequence,targeted for an older and more condensed coring location, was selected for coring based on the sub-bottomgeophysical data that indicated thinning of the upper stratigraphic section, and greater access to the underlyingsection. The results suggest a very dynamic sediment delivery system in a context of Pliocene\u2013Recent Antarcticcontinental margin. The basal section of the core is marked by Eocene-Oligocene reworked taxa while the midsection is characterized by almost barren sediments. The silty top section of the PC03 core, had diatom assem-blages similar to the other kasten and piston cores; t his sectionis characterized by modern diatom assemblagesdominated by Circum Antarctic Current and open water taxa with a variable presence of sea ice associated forms.Glacial slumping, perhaps facilitated by the presence of biogenic silica, and reworking may have removed orprevented deposition within this condensed sedimentary sequence.The presence or absence of F. kerguelensis versus F. barronii and also the presence of transitional forms betweenthese two species, confirms the much older nature of the sediments in this core as compared to the other pistoncores. In addition, Denticulopsis simonsenii much more common at the basal part of the core, may reflect ero-sional contributions from Miocene-aged sediment, while the significant contribution of F. barronii, Thalassiosiralentiginosa and Thalassiosira oliverana (var. sparsa?) versus intervals dominated by D. simonsenii may suggestdifferent sources of material

Seismic markers of the Messinian salinity crisis in the deep Ionian Basin

We conduct the seismic signal analysis on vintage and recently collected multichannel seismic reflection profiles from the Ionian Basin to characterize the deep basin Messinian evaporites. These evaporites were deposited in deep and marginal Mediterranean sedimentary basins as a consequence of the “salinity crisis” between 5.97 and 5.33 Ma, a basin‐wide oceanographic and ecological crisis whose origin remains poorly understood. The seismic markers of the Messinian evaporites in the deep Mediterranean basins can be divided in two end‐members, one of which is the typical “trilogy” of gypsum and clastics (Lower Unit – LU), halite (Mobile Unit – MU) and upper anhydrite and marl layers (Upper Unit – UU) traced in the Western Mediterranean Basins. The other end‐member is a single MU unit subdivided in seven sub‐units by clastic interlayers located in the Levant Basin. The causes of these different seismic expressions of the Messinian salinity crisis (MSC) appear to be related to a morphological separation between the two basins by the structural regional sill of the Sicily Channel. With the aid of velocity analyses and seismic imaging via prestack migration in time and depth domains, we define for the first time the seismic signature of the Messinian evaporites in the deep Ionian Basin, which differs from the known end‐members. In addition, we identify different evaporitic depositional settings suggesting a laterally discontinuous deposition. With the information gathered we quantify the volume of evaporitic deposits in the deep Ionian Basin as 500,000 km3 ± 10%. This figure allows us to speculate that the total volume of salts in the Mediterranean basin is larger than commonly assumed. Different depositional units in the Ionian Basin suggest that during the MSC it was separated from the Western Mediterranean by physical thresholds, from the Po Plain/Northern Adriatic Basin, and the Levant Basin, likely reflecting different hydrological and climatic conditions. Finally, the evidence of erosional surfaces and V‐shaped valleys at the top of the MSC unit, together with sharp evaporites pinch out on evaporite‐free pre‐Messinian structural highs, suggest an extreme Messinian Stage 3 base level draw down in the Ionian Basin. Such evidence should be carefully evaluated in the light of Messinian and post‐Messinian vertical crustal movements in the area. The results of this study demonstrates the importance of extracting from seismic data the Messinian paleotopography, the paleomorphology and the detailed stratal architecture in the in order to advance in the understanding of the deep basins Messinian depositional environments. Highlights First description of a new type of deepwater Messinian salt giant in the Ionian Sea. First quantification of the Messinian salt volume in the Ionian Sea. New seismic evidence of erosional surfces and Lago Mare deposits in the deep Ionian Basin. Further evidence of sea level lowering during the Messinian Salinity Crisis. Evidence for a different, physically separated deepwater Messinian salt basins in the Mediterranean

Seismic hazard for the Trans Adriatic Pipeline (TAP). Part 2: broadband scenarios at the Fier Compressor Station (Albania)

AbstractTo ensure environmental and public safety, critical facilities require rigorous seismic hazard analysis to define seismic input for their design. We consider the case of the Trans Adriatic Pipeline (TAP), which is a pipeline that transports natural gas from the Caspian Sea to southern Italy, crossing active faults and areas characterized by high seismicity levels. For this pipeline, we develop a Probabilistic Seismic Hazard Assessment (PSHA) for the broader area, and, for the selected critical sites, we perform deterministic seismic hazard assessment (DSHA), by calculating shaking scenarios that account for the physics of the source, propagation, and site effects. This paper presents a DSHA for a compressor station located at Fier, along the Albanian coastal region. Considering the location of the most hazardous faults in the study site, revealed by the PSHA disaggregation, we model the ground motion for two different scenarios to simulate the worst-case scenario for this compressor station. We compute broadband waveforms for receivers on soft soils by applying specific transfer functions estimated from the available geotechnical data for the Fier area. The simulations reproduce the variability observed in the ground motion recorded in the near-earthquake source. The vertical ground motion is strong for receivers placed above the rupture areas and should not be ignored in seismic designs; furthermore, our vertical simulations reproduce the displacement and the static offset of the ground motion highlighted in recent studies. This observation confirms the importance of the DSHA analysis in defining the expected pipeline damage functions and permanent soil deformations

Remote sensing as a preliminary analysis for the detection of active tectonic structures: an application to the Albanian orogenic system

As is well known, both the traditional direct geological and geophysical survey methods used to identify geologic features are very expensive and time-consuming procedures. In this regard, remote sensing methods applied to multispectral and medium spatial resolution satellite images allow a more focused approach with respect to the more specific geologic methods. This is achieved by a preliminary land inspection carried out by the semi-automated analysis of satellite imagery. This avoids wasting resources as the geological/geophysical survey methods can be later applied only to those zones suspected of having certain tectonic activity (derived by the remotely sensed imagery). This paper will evaluate an ASTER sensor satellite image (and its derived Digital Elevation Model or DEM), in order to point out the suspected presence of active geologic structures (faults). The area in question is west – central Albania. The results of the remote sensing procedures are later compared with the established data for the same area taken by satellite images, in order to verify the reliability of the adopted method. The source of the established data has been from the bibliography

Seismic evidence for Messinian salt deformation and fluid circulation on the South Balearic margin (Western Mediterranean)

European Geosciences Union General Assembly 2014 (EGU2014), 27 april - 2 may 2014, Vienna, Austria.-- 1 pageThe south Balearic margin is characterized by an abrupt tectonically-controlled transition between a steep continental slope (Emile Baudot escarpment) and the Algero-Balearic abyssal plain, in which Messinain salt-induced deformation affects the seafloor morphology. Multichannel seismic profiles, multibeam bathymetry, and shallow seismic data demonstrate that the extent of salt deformation does not coincide with the bathymetric plain-slope transition. Instead, deformation occurs south of linear structure in the abyssal plain located some tens of kilometres from the base of the slope. The quality of the multi-channel seismic record in the deep water deformed area is severely decreased by the three dimensional character of the salt structures. However, the abyssal plain near the base of the slope reveals details on the Messinian sequence, its structure, post-Messinan deformation, and relation with subsurface fluids. The analysis of part of the EUROFLEETS SALTFLU multichannel seismic data set has included detailed RMS velocity analysis, post-stack and pre-stack time migration. An anomalously thick (up to 800 ms twt) acoustically laminated unit comprising the Messinian Upper Unit (UU) is present near the base of the slope and is characterized by syn-sedimentary gentle symmetric folding. The crests of such folds are affected by small-offset, layer-bound fractures and faults propagating from the upper part to the UU to the Plio-Quaternary sequence. Amplitude anomalies, polarity inversion and at times acoustic blanking reveal the presence of fluids (presumably gas) within the Messinian sequence. A clear seismic evidence for the Mobile Unit (MU, or salt layer) is missing in this area. Seismic evidence for the MU exists south of the linear structural boundary, where salt induced deformation has created vertical displacements of several hundreds of metres, diapiric growth, and at least two salt/mud piercement structures at the seafloor. In the highly deformed area, the UU and the Lower Unit (LU) appear to amalgamate as a consequence of complete salt withdrawal around diapirs. The seismic analysis is focussed on determining whether the boundary between low and high degree of deformation in the abyssal plain is determined by the limit of the salt distribution. In this case the northern limit of the Messinian pure salt basin would not coincide with the present day continental slope, thus requiring either a strong control of Messinian tectonic structures an salt deposition and/or a contamination of salt with clasticsPeer Reviewe

THE MEDITERRANEAN SEA: A NATURAL LABORATORY TO STUDY GAS HYDRATE DYNAMICS?

International audienceGas hydrates have been proven by coring at one site in the (eastern) Mediterranean Sea, but their wider extent remains uncertain. Here we present results from investigations of the potential Mediterranean gas hydrate system, suggesting that clathrates occur more widely and have been strongly impacted by glacial-interglacial climate forcing. Modeling of the methane hydrate stability zone (MHSZ) shows it to be present in most of the Mediterranean Sea, albeit in deep waters (>1000 m) due to warm bottom waters (12.5-14°C) and in greater thicknesses (200-500 m) in the geothermally cooler eastern basin. Comparison of the MHSZ with known or possible zones of gas flux to seabed suggests prospective areas for hydrate occurrence, mainly in the eastern basin. One is the Nile fan, where evidence of the first BSR in the Mediterranean Sea (presented sseparately, Praeg et al. this volume) confirms the potential for additional hydrate discoveries. During glacial stages, gas hydrate stability in the Mediterranean increased due to bottom waters up to 4°C cooler; even allowing for sea levels 125 m lower, the modeled glacial-stage MHSZ was up to 25% thicker and 300 m shallower on basin margins. Glacial-to-interglacial transitions thus corresponded to a marked reduction in hydrate stability, with downslope migration of the upper limit of the MHSZ across depths of c. 700-1000 m. A compilation of submarine landslides in the Mediterranean Sea indicates a peak in the age of slide deposits during the last deglaciation and includes abundant headwalls in mid-to upper slope depths (<1200 m), including on the Nile fan. Together these results suggest that the Mediterranean Sea, in particular its gas-rich eastern basin, offers natural laboratory conditions to test the hypothetical linkages between climate-driven changes in gas hydrate stability and slope instabilities over glacial-interglacial timescales

Capo Granitola-Sciacca Fault Zone (Sicilian Channel, Central Mediterranean): Structure vs magmatism

Highlights • A structural map of the northern part of the Capo Granitola-Sciacca strike-slip Fault Zone (Sicilian Channel) has been produced. • Numerous magmatic manifestations in addition to those already known in the Graham and Terrible banks, have been recognized. • A relationship between magmatism and structures associated with the Capo Granitola-Sciacca Fault Zone, has been documented. • A mechanism of non-plume origin is proposed for the magmatism observed in the study area. The tectonic framework of the northern sector of the Capo Granitola-Sciacca Fault Zone (CGSFZ), a NNE-oriented lithospheric strike-slip fault zone located in the Sicilian Channel (southern Italy), has been reconstructed with the aim to clarify the relationships between geometry and kinematics of the structures and the occurrence and distribution of the magmatic manifestations observed in the area. This has been achieved by the interpretation of a large dataset composed of 2-D multichannel seismic profiles, Chirp profiles, magnetic data and borehole information. In addition to the volcanic edifices known in the Graham and Terribile banks, this study has allowed to recognize several other magmatic manifestations. The magmatic occurrences consist of small volcanic cones, buried magma ascents and potential igneous sills. The CGSFZ is bounded by two strike-slip fault systems, the Capo Granitola Fault System (CGFS) to the west and the Sciacca Fault System (SFS) to the east, dominated by positive flower structures generated by tectonic inversion of NNE-oriented late Miocene extensional faults. Only the southern part of the CGFS shows the presence of a sub-vertical, N-S oriented strike-slip master fault. The sector between the two fault systems does not show a significant Pliocene-Quaternary tectonic deformation, except for its southern part hosting the Terribile Bank, which is dissected by WNW to NW-trending normal faults developed during late Miocene and later reactivated. This set of faults is currently active at the Terribile Bank, whereas is buried by Pliocene-Quaternary deposits in the central and northern sectors of the CGSFZ. The observed magmatism is driven by a mechanism of non-plume origin. Magmas have used as open paths the faults of the CGFS and SFS, which cut the whole lithosphere reaching the asthenosphere and producing partial melting by simple pressure release. Most of the magmatism develops along the strike-slip master fault associated with the CGFS and the normal faults affecting the Terribile Bank. The magmatic feeding of the Terribile Bank would be related to lateral magma migration coming from the structures of the SFS, which would use the open pathways represented by active normal faults. In the central-northern part of the CGSFZ, magmas migrate upward along lithospheric faults, then move laterally and rise toward the surface through NNE and NW-trending buried normal faults. These late Miocene faults do not reach the surface, and this may have favoured the emplacement of igneous sills, which in turn may explain the observed volcanic centres

Deep basin Messinian evaporites on the southern Balearic margin, Western Mediterranean

COST-ANR MEDSALT Symposium, 24-28 October 2016, Palermo, Italy.-- 1 pageThis study is based on multibeam bathymetry and multi-channel seismic reflection data collected during Eurofleets R/V OGS Explora, Cruise No. E12 (SALTFLU), Valencia (Spain) 22/06 - 04/07/2012. Modelling of overpressure evoltion is based on the resulting stratigraphy. The study area encompasses proposed drill sites BAL-02 and BAL-02 of IODP pre-proposal 857B-Pre, Deep-Sea Records of the Messinian Salinity Crisis (DREAM), proposed by J. Lofi et al in 2015. We identify four types of salt-induced abyssal plain sediment deformation structures: (1) a belt of elongated abyssal plain seahills thought to be the attenuated surface expression of salt rollers either produced by reactivated right strike slip faults synthetic to the master fault of the EBE or by differential compaction above such faults; (2) anastomosing knolls in the Menorca Fan area thought to be the product of subsurface salt deformation and gliding triggered by differential sedimentary load; (3) abyssal knolls and seahills spread in the entire abyssal plain across the basin thought to be the product of subsurface salt anticlines and pillows in a relatively more evolved stage of basin evolution affected by basement faulting, perhaps northward propagation of the shortening affecting the Algerian margin; and (4) a small flat topped circular mound in the middle of the abyssal plain interpreted as a mud volcano extruding sediments and fluids of likely pre-Messinian origin. The structures suggest that the crustal transition, not imaged in the seismic data due to intense deformation does not correspond to the Emile Baudot Escarpment (the present day continental tectonically driven continental slope). Rather it is located farther offshore in the deep basin, approximately where intense halokinesis occurs in the abyssal plain, marking the edge of the deep Messinian basin filled with kilometer-thick evaporites. Messinian marginal basins, therefore, are presently located also below the abyssal plain, at the floor of the Emile Baudot Esacarpment. Evidence for sub-salt overpressure is provided by pearchment structures in the deep Messinian basin. A compaction disequilibrium modeling exercise demonstrates that the high sedimentation rate of the thick evaporitic succession in the deep Messinian basin, may indeed generate considerable overpressure, persisting today (overpressure coefficient up to 0.8). However, the reduced evaporite thickness in the marginal basins reduces considerably the likelihood of sub-salt overpressure (overpressure coefficient up to 0.2). Therefore, we conclude that marginal basins belong to different geological domains compared to the deep basin, being the difference given by different crustal structure, evaporite thickness, in some cases evaporite composition (absence of halite layer), and pore pressure regime below and within the evaporitic formations. An upward pore water expulsion system is inferred through the Plio-Quaternary sedimentary cover induced by gypsum dehydration to anhydritePeer Reviewe