scholarly journals Current knowledge on the crustal properties of Italy

1994 ◽  
Vol 37 (5 Sup.) ◽  
Author(s):  
C. Morelli
Keyword(s):  
Adriatic Sea ◽  
Current Knowledge ◽  
Gravity Data ◽  
Maximum Depth ◽  
Gravity Models ◽  
Tyrrhenian Sea ◽  
Po Plain ◽  
Reflection Seismic ◽  
Adriatic Plate ◽  
The North

The recent advances in experimental petrography together with the information derived from the super-deep drilling projects have provided additional constraints for the interpretation of refraction and reflection seismic data. These constraints can also be used in the interpretation of magnetic and gravity data to resolve nonuniqueness. In this study, we re-interpret the magnetic and gravity data of the Italian peninsula and neighbouring areas. In view of the constraints mentioned above, it is now possible to find an agreement between the seismic and gravity models of the Central Alps. By taking into account the overall crustal thickness, we have recognized the existence of three types of Moho: 1) European which extends to the north and west of the peninsula and in the Corsican-Sardinian block. Its margin was the foreland in the Alpine Orogeny and it was the ramp on which European and Adriatic mantle and crustal slices were overthrusted. This additional load caused bending and deepening and the Moho which now lies beneath the Adriatic plate reaching a maximum depth of approximately 75 km. 2) Adriatic (or African) which lies beneath the Po plain, the Apennines and the Adriatic Sea. The average depth of the Moho is about 30-35 km below the Po plain and the Adriatic Sea and it increases toward the Alps and the Tyrrhenian Sea (acting as foreland along this margin). The maximum depth (50 km) is reached in Calabria. 3) Pery-Tyrrhenian. This is an oceanic or thinned continental crust type of Moho. It borders the oceanic Moho of the Tyrrhenian Sea and it acquires a transitional character in the Ligurian and Provençal basins (<15 km thickness) while further thickening occurs toward the East where the Adriatic plate is overthrusted. In addition, the interpretation of the heat flow data appears to confirm the origin of this Moho and its geodynamic allocation.

The Buried Grand Canyon in Egypt: Structural controls on the Neogene River Nile

2020 ◽  
Author(s):  
Ali Abdelkhalek ◽  
Jonas Kley ◽  
Mohamed Hammed ◽  
Ahmed Saied Ali
Keyword(s):  
Early Stage ◽  
Plate Boundary ◽  
Grand Canyon ◽  
Dead Sea ◽  
Maximum Depth ◽  
Gravity Models ◽  
Gulf Of Aqaba ◽  
River Nile ◽  
The North ◽  
Well Data

&lt;p&gt;The origin and intricate history of the River Nile are still widely disputed. Some studies have claimed that the present course of the Nile has formed at ~7-5 Ma, while others have suggested a much longer evolution. We proposed earlier that the southern and central segments of the River Nile in Egypt have originally evolved along a NW trending short-lived rift that was formed by NE-SW extension at ~25-23 Ma, and abandoned at an early stage. Here we focus on the development of the northern segment of the river, which we interpret as having both a relatively young age (~7-6 Ma) and different tectonic evolution. Gravity models and 3D seismic and well data show the presence of a deeply buried canyon west of the northern modern River Nile, 120 km southwest of Cairo, and approximately parallel to its present-day valley with a predominant NNE-NE course. The U-shaped canyon is up to 13 km wide and attains a maximum depth of around 1,900 meters, about as deep as the Grand Canyon of the Colorado River in Arizona, USA. The canyon was cut into a rising plateau along deep-seated NNE to NE-striking faults that formed at ~90-80 Ma as secondary shears to the main structures of the WNW oriented Cretaceous Beni-Suef rift and possibly have been reactivated at ~14 Ma with the origin of the Gulf of Aqaba-Dead Sea NNE sinistral transform plate boundary. The deeply incised canyon formed as a result of severe erosion due to significant sea level drop and desiccation of the Mediterranean in late Miocene time (Messinian Crisis ~7-6 Ma), which was accompanied by continued progressive uplift of the north-eastern Egyptian terrain[KJ1] . [2] The ancestral river excavated and widened a vast braided channel[3]&amp;#160; that cut deeply into Turonian-Campanian sediments in the Beni-Suef basin. The canyon attained its maximum depth by ~5 Ma, and subsequently it was filled by six successive clastic-dominated units of different fluvial facies.[4]&amp;#160;&lt;/p&gt;

scholarly journals The abundance, distribution and speciation of mercury in waters and sediments of the Adriatic Sea

2017 ◽  
Vol 58 (1) ◽  
pp. 165-186 ◽  
Author(s):  
Igor Živković ◽  
Jože Kotnik ◽  
Mladen Šolić ◽  
Milena Horvat
Keyword(s):  
Adriatic Sea ◽  
Current Knowledge ◽  
Mercury Speciation ◽  
Mercury Contamination ◽  
Future Research ◽  
Mercury Species ◽  
Chemical Transformations ◽  
The North ◽  
Marginal Sea ◽  
The Mediterranean

This review focuses on mercury speciation in the Adriatic Sea, a marginal sea of the Mediterranean, which represents its distinct biogeochemical subunit due to anthropogenic mercury loadings. The current knowledge about mercury cycling in the Adriatic is presented through an overview of the state of the art of research in this area: temporal and spatial distributions and occurrence of mercury species in seawater and sediment, and chemical transformations. We summarised research results of mercury speciation in order to describe its presence and fate in the Adriatic Sea. The Adriatic Sea represents a net source of mercury to the Mediterranean Sea due to the highest total mercury concentrations observed in the North Adriatic Sea and the highest methylmercury concentrations in the South Adriatic Pit. However, the biogeochemical cycle of mercury is not completely known and our understanding of mercury transport between compartments and its (bio)transformations is limited. Future research needs to focus on microbial and chemical processes of mercury transformations to improve our understanding of the impacts of mercury contamination on the environment and human health in the Adriatic Sea.

scholarly journals Marine Nematodes from the Shallow Subtidal Coast of the Adriatic Sea: Species List and Distribution

2013 ◽  
Vol 2013 ◽  
pp. 1-9 ◽  
Author(s):  
F. Semprucci
Keyword(s):  
Adriatic Sea ◽  
Current Knowledge ◽  
Nematode Species ◽  
Marine Nematodes ◽  
Marine Nematode ◽  
Species List ◽  
Intertidal Zones ◽  
The North ◽  
Shallow Subtidal ◽  
The Mediterranean

This study is the first attempt aiming to assess the composition and number of free-living marine nematode species on the coasts of the Marches region, Italy. A high number of putative species of nematodes were recognized (84), these belonging to 52 genera in 22 families. Fifty-one taxa have been identified to the species level increasing the number of known nematode species for the Adriatic Sea from 283 to 310 and for the Mediterranean Sea from 700 to 723. The highest diversity and abundance were registered for the nematode families typically of intertidal zones characterized as medium-fine sands. The majority of the species found in the present study are known to occur in the North European coasts or the North Atlantic Sea, the best known regions for nematode distribution. Inferences on the biogeography of marine nematodes are preliminary since most Biodiversity literature concerning the Mediterranean of the basin is very out of date. Considering the great importance of nematodes in the assessment of ecosystem health conditions, an intensification of sampling efforts should be pursued in other regions in order to improve our current knowledge of the distribution pattern of marine nematode species as well as clarify their biogeographical patterns.

scholarly journals Recent deeper geophysical results better account for the tectonics in the Italian area

1997 ◽  
Vol 40 (5) ◽  
Author(s):  
C. Morelli
Keyword(s):  
Oceanic Crust ◽  
Sedimentary Basins ◽  
Tyrrhenian Sea ◽  
Geological Data ◽  
Ligurian Sea ◽  
Po Plain ◽  
Adriatic Plate ◽  
The Alps ◽  
Tectonic Features ◽  
European Plate

Results from extended DSS profiles (1956-1986) in Italy and surrounding land and sea areas offer good constraints for other geophysical and geological data. Integrated interpretations outline the main tectonic features. Collisional tectonics is predominant in the Alps, for which the Adriatic plate acted as hinterland against the European plate foreland. Main results: W-wards, NW- and N-wards oriented overthrusting on the European crust, bending of the lower European crust, European Moho to 70 km depth with the Adriatic mantle indented above, crustal doubling (Adriatic over the European one). In the Apennines, on the contrary, the Adriatic plate acted as a foreland, against the overthrusts generated by the Tuscanian and Tyrrhenian mantellic bodies, heated, elevated and migrated NE-wards and SE-wards, respectively. Also the Adriatic plate bends under this load-centripetally towards the Tyrrhenian sea, so that the Adriatic Moho from 35 km depth is presumed to descend through a flexure till 40-50 km below the Tuscanian and Tyrrhenian land areas. The external peri-Apenninic area is still in compression and includes thick sedimentary basins, from the Po-plain to Sicily. The internal area is in extension, overlapped by thin, stretched crusts of Ligurian and Tyrrhenian origin, whose remnants occupy most of both seas areas, with two areas of oceanic crust in the SE-Tyrrhenian. Rifting and opening is in action also in the Ligurian Sea and Sicily Strait.

Deep crustal structure and tectonic origin of the Tobago-Barbados ridge

2018 ◽  
Vol 6 (2) ◽  
pp. T471-T484 ◽  
Author(s):  
Shenelle Gomez ◽  
Dale Bird ◽  
Paul Mann
Keyword(s):  
Crustal Structure ◽  
Gravity Data ◽  
Seismic Refraction ◽  
Accretionary Prism ◽  
Gravity Models ◽  
Thrust Belt ◽  
Metamorphic Belt ◽  
Seismic Reflection Data ◽  
The North ◽  
Tectonic Origin

The north–south-trending Tobago-Barbados ridge (TBR) extends 250 km from its southern end at the island of Tobago to its northern end at the island of Barbados. On Tobago, exposed metasedimentary and metaigneous rocks have been identified as fragments of a Mesozoic primitive island arc, whereas on Barbados, exposed sedimentary rocks record Paleogene development of the Barbados accretionary prism (BAP). We integrate gravity data with seismic refraction data, well constraints, and seismic reflection data to improve our understanding of the TBR’s crustal structure, uplift mechanism, along-strike compositional variations in the crust, and tectonic origin. Three 2D gravity models suggest that the TBR is underlain by a “pop-up” crustal block uplifted in the trench between the overriding Caribbean plate and the westwardly subducting South American plate. At approximately 11.75° N, the character of the TBR changes over a distance of 60 km from a symmetrical and more elevated, crystalline, thrust fault-bounded structure to a west-verging thrust belt that is less elevated. The symmetrical pop-up and asymmetrical, west-verging thrust belt accommodate east–west, subduction-related shortening that deforms the westernmost edge of the BAP. We think that the crystalline basement of the southern and central TBR is the buried, northeastern continuation of Mesozoic intraoceanic-arc crust and metamorphic belt of Tobago that accreted along the eastern margin of the Great Arc of the Caribbean during its subduction polarity reversal in the early Cretaceous.

Crustal structures of Grenville, Makkovik, and southern Nain provinces along the Lithoprobe ECSOOT Transect: regional seismic refraction and gravity models and their tectonic implications

1998 ◽  
Vol 35 (5) ◽  
pp. 583-601 ◽  
Author(s):  
Keith E Louden ◽  
Jianming Fan
Keyword(s):  
Lower Crust ◽  
Velocity Structure ◽  
Gravity Data ◽  
Seismic Refraction ◽  
Gravity Models ◽  
Grenville Province ◽  
Crustal Layer ◽  
The North ◽  
Crustal Structures ◽  
Lower Crustal

Crustal structures of the eastern Grenville, Makkovik, and southern Nain provinces are determined using seismic reflection-refraction and gravity data along the Lithoprobe Eastern Canadian Shield Onshore-Offshore Transect (ECSOOT). Within the Grenville Province, the velocity model contains a 5 km thick upper crust and a variable-thickness middle to lower crust. The total crustal thickness varies from 25 to 43 km, with the thickest crust in the south and thinnest crust in the north. A high-velocity, lower crustal wedge is coincident with a strong band of northward-dipping reflectors. The two-dimensional velocity structure is compatible with modelling of a 60 mGal gravity high over the Hawke River terrane. In the Makkovik Province, the thickness of upper crustal velocities increases to 17 km. The velocity decrease in the upper to middle crust from the Grenville Province to the Makkovik Province is similar to that of refraction models across the Grenville Front in Ontario and Quebec. It is possibly related to a decrease in metamorphic grade from south to north and (or) a larger volume of unmetamorphosed plutons in the Makkovik Province. A lower crustal layer is coincident with a region of increased reflectivity in the lower crust. There are no major crustal discontinuities associated with terrane boundaries within the Makkovik Province. The base of the crust is consistent with a change from north- to south-dipping reflectors beneath the Cape Harrison domain. Alternatively, it may consist of a thick zone of complex velocity variations, consistent with a zone of diffusive reflectivity observed to the north of the Allik domain.

scholarly journals Description and distribution of the larvae of two species of Fistulariidae (Teleostei, Syngnathiformes) in the southeastern Brazil

2007 ◽  
Vol 7 (1) ◽  
pp. 101-104 ◽  
Author(s):  
Fernanda Bernardo Anacreto Gomes de Barros ◽  
Márcia Salustiano de Castro ◽  
Ana Cristina Teixeira Bonecker
Keyword(s):  
Maximum Depth ◽  
Southeastern Brazil ◽  
Brazilian Coast ◽  
The South ◽  
The North ◽  
Single Genus

Fistulariidae contains the single genus, Fistularia, with four species. Two of these species are recorded from Brazil: Fistularia petimba and F. tabacaria. This study describes larvae of these two species of Fistularia, recording their distribution along the southeastern Brazilian coast, which is limited in the north by Real River (12° S) and in the south by São Tomé Cape (22° S). Samples were collected using a bongo net with mesh apertures of 330 and 500 µm during three oceanographic cruises conducted on spring/98 (Central III), winter/99 (Bahia 1) and autumn/00 (Central IV). The net was towed obliquely and the maximum depth was 200 m. Larvae of F. petimba were the most abundant and most widely distributed within the study area, including the seamounts of the Vitória-Trindade Ridge. Larvae of F. tabacaria were recorded only between 14° S and 21° S.

scholarly journals Hindcasting Soundscapes before and during the COVID-19 Pandemic in Selected Areas of the North Sea and the Adriatic Sea

2021 ◽  
Vol 9 (7) ◽  
pp. 702
Author(s):  
Hüseyin Özkan Sertlek
Keyword(s):  
North Sea ◽  
Adriatic Sea ◽  
Propagation Model ◽  
The North ◽  
Fishing Vessels ◽  
Water Test ◽  
The North Sea ◽  
Monthly Changes ◽  
Source Level ◽  
Sound Maps

The national measures in several European countries during the COVID-19 pandemic also affected offshore human activities, including shipping. In this work, the temporal and spatial variations of shipping sound are calculated for the years before and during the pandemic in selected shallow water test areas from the Southern North Sea and the Adriatic Sea. First, the monthly sound pressure level maps of ships and wind between 2017 and 2020 are calculated for frequencies between 100 Hz to 10 kHz. Next, the monthly changes in these maps are compared. The asymptotic approximation of the hybrid flux-mode propagation model reduces the computational requirements for sound mapping simulations and facilitates the production of a large number of sound maps for different months, depths, frequencies, and ship categories. After the strictest COVID-19 measures were applied in April 2020, the largest decline was observed for the fishing, passenger and recreational ships. Although the changes in the number of fishing vessels are large, their contribution to the soundscape is minor due to their low source level. In both test areas, the spatial exceedance levels and acoustic energies were decreased in 2020 compared to the average of the previous three years.

scholarly journals Deep-Water Cartilaginous Fishes in the Central Mediterranean Sea: Comparison between Geographic Areas with Two Low Impact Tools for Sampling

2021 ◽  
Vol 9 (7) ◽  
pp. 686
Author(s):  
Angela Carluccio ◽  
Francesca Capezzuto ◽  
Porzia Maiorano ◽  
Letizia Sion ◽  
Gianfranco D’Onghia
Keyword(s):  
Adriatic Sea ◽  
Fish Habitat ◽  
Conservation Status ◽  
Abundant Species ◽  
Cartilaginous Fish ◽  
Fish Diversity ◽  
Ionian Sea ◽  
Central Mediterranean ◽  
The North ◽  
North Western

Baited lander represents a low impact technique, an alternative to the traditional trawl sampling for collecting data on fish diversity and abundance, especially for threatened species such as Chondrichthyes living in sensitive habitats. In this study, distribution and abundance of cartilaginous fish were compared between two geographic areas, the southern Adriatic Sea and the north-western Ionian Sea, with two low impact sampling gears, an experimental bottom longline and a baited lander. Species diversity was evaluated by applying ecological indices and difference in mean abundances were tested using multivariate analysis. A total of 13 species of cartilaginous fish were collected. Significant differences in the assemblage recorded in the same area using different sampling tools were detected and no significant differences were detected among different areas explored with the same method. Using longline, the most abundant species collected in both areas was Galeus melastomus, while using lander, the most observed species were Dalatias licha in the southern Adriatic Sea and Hexanchus griseus in the north-western Ionian Sea. According to IUCN classification, of the 13 species collected, 2 are near threatened and 5 are threatened. A better governance of sensitive habitats coinciding with the essential fish habitat for these species would ensure them a better conservation status.

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