A geological overview of the maltese archipelago with reference to the area of Sliema

This study offers an overview and account of the geological and geographical characteristics of the Maltese islands, with a particular emphasis on the Sliema peninsula. The stratigraphic sequence of the geology on the islands, including the lithostratigraphy and sedimentary structure dating back to the Oligo-Miocene Epoch, is described starting from the oldest layer, the Lower Coralline Limestone, up to the most recent rock deposition in the newly discovered quaternary rock deposition. Additionally, the report delves into the general seismic activity on the island that has contributed to the unique geomorphology, hydrology, and hydrogeology that exist on Malta and Gozo. The interrelationship between these geological components is evident on the islands, particularly in the tectonic activity that has resulted in the formation of cliffs and bays throughout. After providing a general geological overview of the islands, the report focuses more specifically on the Sliema area, a town located in the east of the main island of Malta known for its numerous rocky beaches and heavy urbanization.peer-reviewe

Fluid escape structures in the Graham Bank region (Sicily Channel, Central Mediterranean) revealing volcanic and neotectonic activity

In the Sicily Channel, (Central Mediterranean), two geodynamic processes overlap each other, the Maghrebides- Apennines accretionary prism and the Sicily Channel rift. Moreover, the northwestern sector (Banks sector) is characterised by an irregular seafloor morphology linked to the recent volcanic and tectonic activity.In order to discriminate the role exerted by both the processes in the morphostructural setting of the area we used a dataset of both high and very high resolution single-channel and multi-channel profiles, acquired in the frame of the RITMARE project respectively with CHIRP and sparker, and airgun sources, and high resolution (5 m cell) morpho-bathymetric data. The data allowed us to identify and characterise two areas where different geological features (sedimentary and volcanic) are prevailing. They present fluid escaping evidence, which often appears to be active and generating different types of morphologies (both positive and negative). In the western sector we recognised pockmarks at water depths of 195 to 317 m, with diameters from 25 to 580 m, depths from 1.3 to 15 m, and slope up to 23◦ . They show sub-circular shape in plan-view and reflectors with upward concavity in cross section, and are oriented along a NW-SE trend.The CHIRP and multichannel profiles highlight fluids that affect the Plio-Quaternary succession, especially in areas where the top surface of the Messinian succession is shallower. Conversely, wipe-out acoustic facies were recognised in proximity of: i) extensional faults of Mesozoic age with NW-SE trend; ii) dip/strike slip faults of Cenozoic age with NW-SE, N-S and about NNE-SSW trends, and iii) extensional neo-tectonic faults with NW-SE and NNW-SSE trends. We cannot exclude that they could feed the shallower reservoir producing a mixing between the two. In the eastern sector we recognised a cluster of volcanoes composed of seven cone-shaped structures (SCV1-7), pertaining to a wide area known as Graham Bank. A detailed morphometric analysis of these volcanoes has been conducted: they are up to about 115-160 m high and 500-1500 m wide. Most of them show very strongly inclined flanks with 30◦ of average slope. The SCV2 and SCV3 form the Graham Bank, 3.5X2.8 km wide, elongated in the NW-SE direction. At the top of SCV2 focused seepage plumes were observed in the entire water column, through the CHIRP data, where we calculated that they release, a volume of about 10950 m3 and 43960 m3of gases, respectively. In this work, we present the first results of a data collection that have got as main result the identification and mapping of the fluid escape structures revealing the relationship between the active tectonic with migration of fluids, to be used to assess the Submarine Geo-Hazard in the Sicily Channel. We identified two fluid escape fields whose genesis and evolution appear linked to the neotectonic and volcanic activities respectively, that represent the main controlling factors for the migration of fluid; considering the good correlation between pockmarks and the main identified fault systems. In conclusion, our results suggest that the degassing of fluids in this region is rooted at depth, and is mainly aligned with the NW-SE dip/strike slip fault systems, repeatedly reactivated, and linked to the volcanic activity.peer-reviewe

A single-stage megaflood at the termination of the Messinian salinity crisis: Geophysical and modelling evidence from the eastern Mediterranean Basin

Highlights • We analyse seismic stratigraphy of post-Messinian succession in west Ionian Basin. • Termination of Messinian salinity crisis consisted of a single-stage Zanclean flood. • Megaflood followed a sea level drawdown of 1900 m in eastern Mediterranean. • Fine, well-sorted sediments are predicted in the thicker sections of flood deposit. • NW Ionian Basin hosts evidence of episodic slope instability after 1.8 Ma. Abstract The Messinian salinity crisis was an extraordinary event that resulted in the deposition of kilometre-thick evaporite sequences in the Mediterranean Sea after the latter became disconnected from the world's oceans. The return to fully and stable marine conditions at the end of the crisis is still subject to debate. Three main hypotheses, based on geophysical and borehole data, onshore outcrops and climate simulations, have been put forward. These include a single-stage catastrophic flood, a two-step reflooding scenario, and an overspill of Paratethyan water followed by Atlantic inflow. In this study, two research questions are addressed: (i) Which event marked the termination of the Messinian salinity crisis? (ii) What was the sea level in the eastern Mediterranean Sea during this event? Geophysical data from the western Ionian Basin are integrated with numerical simulations to infer that the termination of the crisis consisted of a single-stage megaflood following a sea level drawdown of 1900 m. This megaflood deposited an extensive sedimentary body with a chaotic to transparent seismic signature at the base of the Malta Escarpment. Fine, well-sorted sediments are predicted to have been deposited within the thicker sections of the flood deposit, whereas a more variable distribution of coarser sediments is expected elsewhere. The north-western Ionian Basin hosts evidence of episodic post-Messinian salinity crisis slope instability events in the last ~1.8 Ma. The largest of these emplaced a >200 km3 deposit and is associated with failure of the head of Noto Canyon (offshore SE Sicily). Apart from unravelling the final phase of the Messinian salinity crisis and the ensuing stratigraphic evolution of the western Ionian Basin, our results are also relevant to better understand megafloods, which are some of the most catastrophic geological processes on Earth and Mars

Active degassing across the Maltese Islands (Mediterranean Sea) and implications for its neotectonics

The Maltese Islands, located in the central Mediterranean Sea, are intersected by two normal fault systems associated with continental rifting to the south. Due to a lack of evidence for offshore displacement and insignificant historical seismicity, the systems are thought to be inactive and the rift-related deformation is believed to have ceased. In this study we integrate aerial, marine and onshore geological, geophysical and geochemical data from the Maltese Islands to demonstrate that the majority of faults offshore the archipelago underwent extensional to transtensional deformation during the last 20 ka. We also document an active fluid flow system responsible for degassing of CH4 and CO2. The gases migrate through carbonate bedrock and overlying sedimentary layers via focused pathways, such as faults and pipe structures, and possibly via diffuse pathways, such as fractures. Where the gases seep offshore, they form pockmarks and rise through the water column into the atmosphere. Gas migration and seepage implies that the onshore and offshore faults systems are permeable and that they were active recently and simultaneously. The latter can be explained by a transtensional system involving two right-stepping, right-lateral NW-SE trending faults, either binding a pull-apart basin between the islands of Malta and Gozo or associated with minor connecting antitethic structures. Such a configuration may be responsible for the generation or reactivation of faults onshore and offshore the Maltese Islands, and fits into the modern divergent strain-stress regime inferred from geodetic data

Voyage Report RV Tangaroa Voyage TAN1703, 5 April – 1 May 2017

Meteoric recharge and topographically-driven flow are the most important sources of groundwater recharge in terrestrial settings. In passive continental margins, topographically driven meteoric (TDM) groundwater is only one of a range of drivers of offshore groundwater flow. Other drivers include seawater recirculation, sediment loading, geothermal convection, and diagenesis. Sea level has been much lower than today for 80% of the Quaternary, resulting in the emergence of extensive sections of continental shelf, a reduction of pressure exerted by the sea water column, as well as steepening of the hydraulic gradient and an increase in hydraulic head. The potential of TDM recharge to establish extensive water tables, create massive groundwater fluxes, and generate pore overpressures and discharges across the continental shelf and upper continental slope must have been significantly higher during the majority of the last 2.6 Ma than it is today. Considering that geothermal convection is strongest beneath the continental slope and tends to be dominated by TDM flow during sea level lowstands, whereas sediment loading is most important during rapid deglaciations in high sedimentation zones, TDM recharge is a likely very important driver of offshore groundwater systems in continental shelves and upper slopes globally.peer-reviewe

Fluid escape structures revealing volcanic and tectonic activity in the Graham Bank (Sicily Channel)

The Graham Bank (NW Sicily Channel, Central Mediterranean) is characterised by a complex seafloor morphology, where morphostructural highs, submarine plain, escarpments, and negative and positive relieves indicate a complex structural setting and the occurrence of seepage fluids. New high-resolution acoustic data (multibeam, Chirp profiles) and multi-channel profiles, allowed us to differentiate two main morphological sectors, and to identify several pockmarks and mounds linked to fluid escape phenomena. The eastern sector, corresponding to the volcanic edifices of the Graham Bank, is characterised by volcanic context with rough morphology, several mounds, focused seepage plumes and magmatic acoustic substrate, all related to the activity forming both the Graham Bank and the new volcanic cones here identified. The western sector displays a generally flat morphology dominated by Late Pleistocene-Holocene outer shelf deposits, where mounds and pockmarks with sub-circular and ellipsoidal shapes, V- to U-shaped in cross-section, are the prevailing features indicating the migration of fluids to the seafloor. These two areas are separated by a vertical deep fault forming a deeply incised channel with NW-SE direction. The latter is bordered by steep walls forming fault escarpments, which shed the eroded materials to the adjacent lower slope and deep-water zones. The overall morphostructural setting suggests a tectonic control in the morphological conformation of the seabed and in the distribution of both pockmarks and mounds. The aligned mounds have both NW-SE and NNW-SSE orientation, sometimes extending several hundred metres and forming hummocky surfaces. The aligned pockmarks are strictly comparable to the orientation of the faults related to the most recent tectonic activity. The good correlation between fluid escape structures and the main fault systems involving the kilometric sedimentary cover suggests that the degassing of fluids is rooted in depth revealing that extensional tectonics acts with very deep subvertical recent faults developing along and reactivating the Cenozoic (both Plio-Quaternary and Messinian) and Mesozoic tectonic systems.peer-reviewe

Volcano- and neoectonic-related slope failures in the north-western Sicily Channel (Central Mediterranean Sea) : implications for understanding and assessing geohazard risk

The southern Sicily coasts represent an important contribution to Italian tourism and marine geological processes in the Sicily Channel could pose a significant risk to neighbouring populations and goods. In this work, we are presenting the first results of the data collection that allowed us to identify and map several geological elements that can be used to assess submarine geohazards in the Sicily Channel. By using multibeam data and high-resolution seismic reflection profiles acquired during the ACUSCAL 2015 Cruise, we defined the characteristics of the morphostructural highs, and the morphology of slope failures and the stratigraphy of the mass transport deposits (MTD).peer-reviewe

Active faulting offshore the Maltese Islands revealed by geophysical and geochemical observations

The Maltese Islands (central Mediterranean Sea) are intersected by two normal fault systems associated with continental rifting to the south. Because of a lack of evidence for offshore displacement and insignificant historical seismicity, the systems have been considered to be inactive. Here we integrate aerial and marine geological, geophysical and geochemical data to demonstrate that: (i) the majority of faults offshore the Maltese Islands underwent extensional to transtensional deformation during the last 20 ka, (ii) active degassing of CH4 and CO2 occurs via these faults. The gases migrate through Miocene carbonate bedrock and the overlying Plio-Pleistocene sedimentary layers to generate pockmarks at the muddy seafloor and rise through the water column into the atmosphere. We infer that the offshore faults systems are permeable and that they were active recently and simultaneously. The latter can be explained by a transtensional system involving two right-stepping, right-lateral NW-SE trending faults, either binding a pull-apart basin between the islands of Malta and Gozo or associated with minor connecting antitethic structures. Such a configuration may be responsible for the generation or reactivation of faults onshore and offshore the Maltese Islands, and fits into the modern divergent strain-stress regime inferred from geodetic data.peer-reviewe

SOME PRODUCTION AND NUTRITION PARAMETERS IN VARIOUS SYSTEMS OF COW KEEPING IN EARLY LACTATION

Analizirani su proizvodni pokazatelji i utrošak hrane po jedinici proizvoda u dvije grupe od po 26 grla muznih krava, holštajn-frizijske pasmine koje su se telile u siječnju 1989. godine. Ispitivanja su vršena na farmi slobodnog sistema držanja, kapaciteta 1000 grla s instaliranom kompjuterskom opremom za rukovođenje procesima proizvodnje. Životinje su praćene od telenja do 35. dana laktacije. Ogledna grupa je od 6. dana laktacije bila u slobodnom sistemu držanja, dok je kontrolna grupa bila tokom čitavog trajanja ogleda u klasičnoj staji na vezu. Željelo se ustanoviti mogućnost uvoda krava u mlječnost u slobodnom sistemu držanja s hranidbom koncentrata preko automatskih hranilica i mužnjom u izmuzištu, sa automatikom za individualno praćenje proizvodnje. Ustanovljeno je da kompjuterski sistem omogućava uvod krava u mlječnost u slobodnom sistemu držanja,bez negativnih posljedica na proizvodnju, te da se ostvaruje utrošak hrane po jedinici proizvoda isti kao u klasičnoj staji na vezu.Production indicators and food consumption per product unit in two groups of 26 Holstein-Frisian dairy cows calved in January 1989 were analyzed. Investigations were carried out on a free system dairy farm, capacity a 1000 head, with a computer installed to follow\u27 the production processes. The cows were followed from calčvng until 35- day of lactation. The trial group was kept free from the 6rh lactation day hile the control group was kept tied in a traditional shed during the trial period. The aim was to establish a possibility of introducing the cows to being milked in a free system and fed on concentrates by means of automatic feeding system and milked in the milking parlour; each animal as followed by the computer system. It as established that the computer system enabled initiations of cows into milking in the free keeping system without negative effects on production and that the food consumption per production unit as the same as when the cows were kept tied in a traditional shed