Search results for "feature"
showing 10 items of 4091 documents
A visual framework to create photorealistic retinal vessels for diagnosis purposes
2020
The methods developed in recent years for synthesising an ocular fundus can be been divided into two main categories. The first category of methods involves the development of an anatomical model of the eye, where artificial images are generated using appropriate parameters for modelling the vascular networks and fundus. The second type of method has been made possible by the development of deep learning techniques and improvements in the performance of hardware (especially graphics cards equipped with a large number of cores). The methodology proposed here to produce high-resolution synthetic fundus images is intended to be an alternative to the increasingly widespread use of generative ad…
Volcanological evolution of Pantelleria Island (Strait of Sicily) peralkaline volcano: a review
2022
International audience; Pantelleria volcano has a particularly intriguing evolutionary history intimately related to the peralkaline composition of its explosively erupted magmas. Due to the stratigraphic complexity, studies over the last two decades have explored either only the pre-Green Tuff ignimbrite volcanism or the post-Green Tuff activity. We here focus on the whole evolutionary history, detailing the achievements since the first pioneering studies, in order to illustrate how the adoption and integration of progressively more accurate methods (40 Ar/ 39 Ar, paleomagnetism, petrography, and detailed field study) have provided many important independent answers to unresolved questions…
First Early Pliocene micromammal faunas from Venta del Moro (Cabriel Basin, Spain) : new data on the Messinian dispersal of Debruijnimys
2021
The localities of La Bullana 3 and LA Bullana 2B (Valencia, E Spain) have yielded remains of Apodemusgorafensis, Paraethomys aff. abaigari, Stephanomys dubari, Apocricetus barrierei, Sciuridae indet. and Asoriculus cf. gibberodon the former, and Apodemusgorafensis, Paraethomys aff. abaigari, Stephanomys dubari, Apocricetus barrierei, Sciuridae indet., Asoriculus cf. gibberodon, Castillomysgracilis, Occitanomysbrailloni, Occitanomys sp., Paraethomys meini, Ruscinomys sp., Eliomys intermedius, Debruijnimys cf. julii and Atlantoxerussp. the latter. Based on the study of these micromammal assemblages, we propose an Early Pliocene age (MN14) for both sites. The pres-ence a gerbilid related to De…
Geomorphological west-east-section through the north chilean andes near antofagasta
2006
The extremely arid western slope of the Andes near Antofagasta is an area of young tectonic movements on the one hand, but of very low erosion rates on the other. Therefore the relief is characterized by very old erosional forms, but fresh and clearly visible tectonic forms. This is quite evident from the following characteristics of a west-east-section from the Coastal Cordillera to the High Cordillera: 1. The great height and steepness of the western escarpment of the Coastal Cordillera, devoid of deep valleys. 2. The preservation of the miocene and pliocene caliche deposits with highly soluble nitrates in the eastern part of the Coastal Cordillera and of the landforms covered by them. 3.…
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…
Speleogenesis of the Hermannshöhle cave system (Austria): Constraints from 230Th/U-dating and palaeomagnetic analysis
2015
Hermannshöhle is a show cave located near Kirchberg/Wechsel in Lower Austria. Together with three nearby and genetically connected caves, it forms the Hermannshöhlen cave system (HHS). With a length of 5 km, the HHS is the longest cave in the Lower Austroalpine unit. It is arranged as an extreme three-dimensional maze on a ground area of 200 x 200 x 82 m. Speleothems are abundant in this cave and represent the focus of this study. Low carbon isotope values indicate the presence of a soil-covered catchment above the HHS during times of speleothem deposition. 28 samples were dated by the 230Th/U-method and, in combination with palaeomagnetic data from a 5 m-high sediment profile, indicate mul…
New bradorid arthropods from the Lower Cambrian of Spain
2007
Lower Early Cambrian rocks of the Pedroche Formation in the Sierra de Cordoba consist of well-exposed mixed facies with abundant fossil assemblages showing long stratigraphical ranges. These assemblages include diverse Ovetian archaeocyaths, trilobites, small shelly fossils, calcimicrobia, trace fossils, and stromatolites. For the ostracod-like Cambriidae it is the first record from the Iberian Peninsula. Cordubiella pedrochensis n.gen. n.sp. comes from two sections of the lower Pedroche Formation: the Arroyo de Pedroche 1 sec- tion, and the Arroyo Pedroche 2 section. The material was collected in the zone of Lemdadella perejoni, of lower Ovetian age and below the Eoredlichia FAD. It supple…
A sequence analyzed from the basin to the platform : the Middle Oxfordian calcareous succession in southeastern France
2004
Abstract Middle Oxfordian sedimentation is very homogeneous in southeastern France. It is characterized by a specific alternation of marls and fine-grained limestones (G. transversarium Zone). This work shows that sets of calcareous beds allow accurate stratigraphic correlations in various paleogeographic areas, from the shallow Jura platform to the deep Dauphinois basin. Following a rifting period, this sedimentation illustrates a doming period with decreasing subsidence and water depth. This corresponds to the establishment of a wide marine area more favourable to carbonate sedimentation. Considering sequence stratigraphy, some slight variations occur in the sediment record and lead to in…
Collapse structures in the Permian of the Saar-Nahe area, Southwest Germany
1971
Volcanic breccias near an intrusive rhyolite dome in the Permian Saar-Nahe trough of southwest Germany have been identified as complex pipe-like subsidence-structures occupying the site and immediate neighbourhood of “explosive” volcanoes.
The origin and glaciodynamic significance of sandstone ridge networks from the Hirnantian glaciation of the Djado Basin (Niger)
2007
The Djado Basin (Niger) was located beneath the inner part of the Late Ordovician ice sheet. The Felar-Felar Formation consists mainly of glaciomarine deposits, associated with the major ice sheet recession within the glaciation, and is bounded by two glacial unconformities. Structures corresponding to sandstone ridges are found within the Felar-Felar Formation. Sandstone ridges are several metres high, about 10 m wide and hundreds of metres long. These structures are organized in extensive anastomosed to subpolygonal networks. The association of sandstone ridge networks with the later glacial unconformity and with other glacial evidence suggests sub-glacial conditions for their origin. San…