1,720,974 research outputs found
A study of the morphological variability of Radiolites marinii Caffau & Plenicar (Radiolitidae), Late Cenomanian, Karst of Gorizia, Italy
No full textThe species Radiolites marinii Caffau & Plenicar is very abundant in the rudist assemblages of the limestone sequence of the area of "Archi", in the southeastern part of Karst of Gorizia, from the Upper Cenomanian age.
The good preservation-state of several specimens found separately in the dolonstone allowed to analyse and describe in detail the external morphology of the shell of this species. The main feature of the external morphology is the difference between the upper and the lower part of the shell.
Morphometrical values regarding the shell area (Sa), the inner area of the shell (Ia), the external perimeter (Ep) and the internal perimeter (Ip) of the shell were obtained from each transverse section by image analysis.
The analysis of these data indicated that the change in morphology could be due to a strong biological stress that markedly influenced the physiological trend of calcitic secretion for the building up of the shell in individuals of this species
Some taphonomic aspects of the benthic foraminifers from Tremiti Islands (Central Adriatic Sea).
No full textAbstract - Post-mortem transport of foraminiferal tests in shallow-waters sediments is reported by several authors. To evidence these phenomena, data regarding some taphonomic aspects of the benthic foraminifers assemblages from Tremiti Islands are reported. The test preservation, represented by the percentage of fragmentation, indicates that high values correspond rather well with the coarse sands and fine gravels under bottom currents (SGCF) biocoenosis distribution. The occurrence of variable quantity of sub-recent fossils foraminifers in recent sediments is not dependent on the Cenozoic outcrops supply, but rather it can represent previous paeloenvironments, linked to the late Quaternary sea level variations. A dimensional statistical study on Elphidium crispum, by mean of Matrox Inspector 3.0 software, are reported from 117 tests random selected from three stations. Together with the textural characteristics of the sediments, the sorting degree of the tests in the TRE19 and 26 samples may testify that the wave-motion is more active on the northwestern windward side of the islands, touched by more recurrent storm surges. On the contrary, low sorting of E. crispum population in sediments from the southern side of the Archipelago (TRE9 sample), could be considered as autochthonous, indicating the lower hydro dynamism of this sector.
Key-words: Tremiti Islands, foraminifers, taphonomy, sediments
Sedimentazione recente sul prisma costiero del Molise (Adriatico centrale)
No full textSi esamina la composizione tessiturale di 52 campioni di sedimento di fondo prelevati sul prisma costiero Molisano fino all’isobata di 50 m. Da riva verso il largo viene verificato lo stile di sedimentazione per bande subparallele alla costa, ben noto nell’Adriatico centrale, ove la sedimentazione è condizionata dal moto ondoso e dal regime delle correnti litorali. L’estremo limite di influenza verso terra del sistema delle correnti del largo viene segnalato dalle peliti attorno alla batimetrica –50m.
Lo studio, basato sulla cluster analysis delle frazioni sabbiosa e pelitica, evidenzia numerosi dettagli della sedimentazione costiera. In particolare, la distribuzione della frazione fine permette la ricostruzione dell’espansione media a mare delle plumes fluviali, estesa fino a 10-15 km dalla foce
Aspetti sedimentologici e morfologici della piattaforma continentale salentina (Adriatico meridionale e Ionio)
No full textIl Museo Nazionale dell’Antartide. Uno sguardo agli ambienti estremi
Full text linkDefinire la missione culturale del Museo Nazionale dell’Antartide e, in generale dei musei scientifici, è considerata generalmente una questione complessa. Il museo deve proporsi come luogo di scoperta, che fornisce stimoli alla curiosità, senza pretendere di essere esauriente, ma piuttosto riuscendo a far assaporare la scienza, tanto da rendere il visitatore non solo fruitore ma anche produttore e soggetto principale di cultura. In tal senso i musei scientifici possono e devono avere un ruolo determinante nel promuovere la diffusione della cultura scientifica, coinvolgendo il pubblico di ogni età, fornendo informazioni, conoscenze, stimoli e motivazioni all’apprendimento.
La realizzazione a Trieste del Museo Nazionale dell’Antartide si offre a questa prospettiva usufruendo, in quanto centro interuniversitario preposto anche alla ricerca, del mondo della cultura universitaria, e trasferendola in modo semplificato alla società civile. La concretizzazione, infatti, di una moderna esposizione con annesse aule conferenze, laboratori didattici ed attività diversificate di divulgazione temporanea, tra cui la capacità di analisi e studio di moderne metodiche didattico/divulgative, realizza un ponte tra la cultura scientifica di alto livello e la divulgazione della stessa verso l’utenza media.
Defining the cultural mission of the National Museum of Antarctica and in general of science museums is a complex issue. The museum should present itself as a place of discovery, which provides incentives to curiosity, without claiming to be exhaustive, but rather managing to enjoy science, so as to make the visitor not only the user but also a producer and main subject of culture.
Science museums can and should play a key role in promoting the diffusion of scientific culture involving an audience of all ages, providing information, knowledge, incentives and motivation to learn. In this context the realization of the National Museum of Antarctica in Trieste offers the opportunity to interact with the world of university culture. A modern exhibition that includes classroom lectures, educational workshops and diversified temporary exhibitions can create a bridge between scientific culture and society
Image analysis contribution for the palaenvironmental characterisation of sedimentary sequences of the Western Ross Sea (Antarctica)
No full textThis study illustrates a specialised system that is able to process two-dimensional images of sand grains obtained by means of a videocamera mounted on a microscope. By using image processing techniques, it is possible to extract the geometric parameters and calculate the morphometric indexes of a large number of samples in an automatic way. A quantitative evaluation of such features for a certain number of clasts enables objective comparisons among sediments with different origin and “sedimentary history”.
The system has already been planned and tested within the framework of PNRA (Programma Nazionale di Ricerche in Antartide) by the Department of Biophysical and Electronic Engineering (University of Genoa) in co-operation with the Department of Geological, Environmental and Marine Sciences (University of Trieste), (Venturi et al., 1994; Protopsalti, 1997).
The aim of the work is to check whether the morphometric analysis can confirm the genetic interpretations available from sedimentological, stratigraphic and mineralogical data of sampled sedimentary bodies.
This investigation considers the 500-210 μm sand fraction of sedimentary deposits sampled at the bottom of the Ross Sea. Approximately 3800 quartz grains have been analysed from 19 levels of 3 different cores: ANTA91-30 and ANTA91-29 collected in the Drygalski Basin and ANTA91-19 collected in the Joides Basin
Anthropogenic mercury in coastal sediments of the Guanabara Bay (Rio De Janeiro, Brazil)
No full textSea-floor sedimentological and morphological mapping of Tremiti Islands (Adriatic Sea)
No full textThe Tremiti Islands are an isolated archipelago in the Adriatic Sea approximately 40 km east of Termoli and 20 km north of the Gargano Promontory. San Nicola, San Domino, Caprara and Cretaccio are the main islands belonging to this archipelago.
In the frame of the C.N.R. Project Prisma 2 – Sottoprogetto 3, about 200 bottom sediments were collected during three oceanographic cruises (1997, 1998, 2001), between 5 and 100 m depth. The aim of this work is to provide some textural distributions of bottom sediments related to the sea-floor morphology.
Sedimentological and textural maps of recent sediments are presented, adopting two different textural classifications: a ternary one (end-members: gravel, sand and mud) according to Folk (1965) and a binary one (end-members: sand and pelite) suggested by Nota (1958).
The sediment textural patterns are strongly affected by wave motion and bottom currents in the northern side of the islands; conversely sedimentation processes are influenced by lower bottom energy at the sea-floor in the southern sector of the archipelago.
In conclusion, it appears that the sea-floor sedimentation of this area, is better described by Folk’s classification because of gravel amount. The occurrence of this fraction outlines the numerous break slopes and steps characterising the complex morphology of the sea-floor due to Holocene sea-level rise and/or the tectonic uplift of the submerged body of the archipelago
Contributo dell’image analysis alla caratterizzazione paleoambientale di sequenze sedimentarie nel Mare di Ross occidentale
No full textQuesto lavoro, sviluppato in seno al Programma PNRA dal DIBE (Università di Genova) in stretta collaborazione con il Dipartimento di Scienze Geologiche, Ambientali e Marine dell'Università di Trieste, illustra come un metodo di parametrizzazione morfometrica bidimensionale di clasti di sabbia, per mezzo di imaging, possa fornire un contributo aggiuntivo alla caraterizzazione paleoambientale di sequenze sedimentarie
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