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

Oceanographic and climatic consequences of the tectonic evolution of the southern scotia sea basins, Antarctica

The Scotia Sea is a complex geological area located in the Southern Ocean which evolution is closely linked to the opening of the Drake Passage. Structural highs of continental nature derived from the former continental bridge between South America and the Antarctic Peninsula surround the abyssal plains of the Scotia Sea, restricting small isolated sedimentary basins along its southern margin. Morpho-structural and seismo-stratigraphic analyses of multichannel seismic reflection profiles, and additional geophysical data available in the region, have been conducted, decoding regional and global implications of the basins' evolution. The main aim of this work is to describe the stratigraphic evolution of the southern Scotia Sea basins, from their opening in the back-arc tectonic context of the Scotia Sea, to the last oceanographic changes which have carried on global climatic implications. The evolution of the south Scotia Sea occurred through two major tectonic stages registered in the sedimentary record of the region: 1) the end of the subduction in the northwest part of the Weddell Sea during the early Miocene, which shortened the back-arc subduction trench generating a major change in the regional tectonic field that determined the evolution of the southern basins towards two different types of passive margins: magma-poor and magma-rich; and 2) the full development of the southern Scotia Sea basins during the middle Miocene, that led to the opening of deep oceanic gateways along the South Scotia Ridge. Interplay among tectonics, oceanography and climate is proposed to control the regional sedimentary stacking pattern, with coeval changes globally identified

Satellite imagery elaboration (aster sensor, terra satellite), in order to map rock distribution in extreme areas. the Prince Albert mountain chain (Victoria land - Antartica)

The present paper is a first attempt to use Remote Sensing and GIS methodologies in order to draw a rock distribution map in a extreme land as Antarctica. To this aim we elaborated an ASTER sensor image (Terra satellite). This sensor records medium resolution satellite images (from 15 m to 90 m pixels) in 14 different bands (from visible to thermal infrared). In the scientific community ASTER data represent a new tool in order to create land use maps, thermal distribution maps and 3d models of the territory. The adopted methodology is applied to a training area in Prince Albert mountain chain (Trans Antarctica Ridge \u2013 Victoria Land \u2013 Antarctica). We checked the spectral response of the satellite image pixels; then we estimated the kind of rock by the presence of different minerals in it. We did this comparing the reflectance values of the satellite image pixels with the one recorded in laboratory on each mineral in the different wavelengths corresponding to the ASTER sensor 14 bands. In order to control our estimation, we used a geologic map of the same area. This one was drawn within the framework of the Italian National Research Program in Antarctica (PNRA). We choose a ASTER sensor satellite scene recorded in the period of maximum ice cover on the land, in order to grant a minimum outcrop in the case of an eventual manual check in Antarctica