Search results for "Island"
showing 10 items of 761 documents
Reassessment of continental growth during the accretionary history of the Central Asian Orogenic Belt
2014
We argue that the production of mantle-derived or juvenile continental crust during the accretionary history of the Central Asian Orogenic Belt (CAOB) has been grossly overestimated. This is because previous assessments only considered the Palaeozoic evolution of the belt, whereas its accretionary history already began in the latest Mesoproterozoic. Furthermore, much of the juvenile growth in Central Asia occurred in late Permian and Mesozoic times, after completion of CAOB evolution, and perhaps related to major plume activity. We demonstrate from zircon ages and Nd–Hf isotopic systematics from selected terranes within the CAOB that many Neoproterozoic to Palaeozoic granitoids in the accre…
Tectonic models for accretion of the Central Asian Orogenic Belt
2007
The Central Asian Orogenic Belt ( c . 1000–250 Ma) formed by accretion of island arcs, ophiolites, oceanic islands, seamounts, accretionary wedges, oceanic plateaux and microcontinents in a manner comparable with that of circum-Pacific Mesozoic–Cenozoic accretionary orogens. Palaeomagnetic and palaeofloral data indicate that early accretion (Vendian–Ordovician) took place when Baltica and Siberia were separated by a wide ocean. Island arcs and Precambrian microcontinents accreted to the active margins of the two continents or amalgamated in an oceanic setting (as in Kazakhstan) by roll-back and collision, forming a huge accretionary collage. The Palaeo-Asian Ocean closed in the Permian with…
Late Hercynian Plate and Intraplate Processes within Europe
1987
The Hercynian orogenic belt of Europe consists of a central crystalline ridge which is accompanied on both sides by a rather unmetamorphosed foldbelt. It is speculated that the crystalline ridge represents some kind of island arc system underlain by a segment of continental crust. On both sides this island arc system was involved in subduction of oceanic crust, first of the Mideuropean Sea in the North and then of the Paleotethys in the South. When the continental areas to the north and south of the oceanic areas (North America/Northern Europe and Africa) finally got involved in the subduction processes, continent/continent collision took place on both sides of the island arc system. The tw…
Near 100% Renewable Island with sea wave energy. The case study of Pantelleria in Mediterranean sea
2016
The first aim of this work is to explore the possibility of the transition of a real islanded network from one that is “fuel-based” to a “renewable-based” one. This transition is analysed for the real MV/LV distribution system of the island of Pantelleria, in the Mediterranean Sea. Particularly, this work is focused on a Renewable source nowadays totally unused: wave energy. Thanks to the innovative generator prototype designed by Department of Energy of University of Palermo (Italy), wave energy is able to represent a primary source for the production of electric energy in the Mediterranean islands. The procedures applied in the present article, as well as the main equations used, are the …
Can MPS's protect sea urchin stocks?
2017
Sea urchins have long attracted attention from scientists worldwide for their ecological role in coastal areas. Entire communities structures associated to kelp beds and related ecosystem functions were found to strictly depend on grazing by urchins. Sea urchins, in addition, have been used as a food resource by humans since prehistory, and presently they are one of the important sea food (both exploited from the wild and in part obtained from aquaculture) consumed in many regions, but also exported-imported through the world. In the Mediterranean sea, the purple sea urchin Paracentrotus lividus (Lamarck) exerts a key ecological as a main regulator of the structure of coastal communities. A…
Data from: Getting there and around: host range oscillations during colonisation of the Canary Islands by the parasitic nematode Spauligodon
2017
Episodes of expansion and isolation in geographic range over space and time, during which parasites have the opportunity to expand their host range, are linked to the development of host-parasite mosaic assemblages and parasite diversification. In this study we investigated whether island colonisation events lead to host range oscillations in a taxon of host-specific parasitic nematodes of the genus Spauligodon in the Canary Islands. We further investigated if range oscillations also resulted in shifts in host breadth (i.e. specialization), as expected for parasites on islands. Parasite phylogeny and divergence time estimates were inferred from molecular data with Bayesian methods. Host div…
Geochemical constraints on the provenance and depositional setting of sedimentary rocks from the islands of Chios, Inousses and Psara, Aegean Sea, Gr…
2007
The provenance and depositional setting of Late Palaeozoic and Early Mesozoic clastic sediments from the eastern Aegean archipelago are examined here for the first time using whole-rock geochemistry and composition of detrital chrome spinel. Major- and trace-element data for Late Palaeozoic and Permo-Triassic clastic sediments from the Lower and Upper Units of Chios are compatible with an acidic to intermediate source, minor input of (ultra)mafic detritus and recycling of older sedimentary components. Chondrite-normalized REE profiles are uniform with light REE enrichments (La N /Yb N c . 7.7), negative Eu anomalies (Eu/Eu* c . 0.67) and flat heavy REE patterns (Gd N /Yb N c . 1.5), indicat…
Stability of the heaviest elements: K isomer in No250
2020
Decay spectroscopy of No250 has been performed using digital electronics and pulse-shape analysis of the fast nuclear decays for the first time. Previous studies of No250 reported two distinct fission decay lifetimes, related to the direct fission of the ground state and to the decay of an isomeric state but without the possibility to determine if the isomeric state decayed directly via fission or via internal electromagnetic transitions to the ground state. The data obtained in the current experiment allowed the puzzle to finally be resolved, attributing the shorter half-life of t1/2=3.8±0.3μs to the ground state and the longer half-life t1/2=34.9−3.2+3.9μs to the decay of an isomeric stat…
“Safe” Coulomb Excitation ofMg30
2005
We report on the first radioactive beam experiment performed at the recently commissioned REX-ISOLDE facility at CERN in conjunction with the highly efficient γ spectrometer MINIBALL. Using Mg-30 ions accelerated to an energy of 2.25 MeV/u together with a thin Ni-nat target, Coulomb excitation of the first excited 2(+) states of the projectile and target nuclei well below the Coulomb barrier was observed. From the measured relative deexcitation γ-ray yields the B(E2;0(gs)(+)R 2(1)(+)) value of Mg-30 was determined to be 241(31)e(2) fm(4). Our result is lower than values obtained at projectile fragmentation facilities using the intermediate-energy Coulomb excitation method, and confirms the …
Understanding the nuclear structure of heavy elements
2013
The study of heavy and superheavy elements has always been one of the cornerstones of nuclear physics studies. These studies are driven by a desire to create new elements and to determine the limits of nuclear stability. Current experiments to synthesize new elements aim at the fabled ?Island of Stability? which should be found in the region of the next ?magic? numbers for protons and neutrons beyond Z?=?82 and N?=?126 (208Pb). The island is predicted to be around proton number 114?126 and neutron number 184. In recent years, another approach to understanding heavy nuclear systems has gained momentum, whereby nuclei with a much lower proton number of around 100 are studied in detail. The mo…