Sardinia Coastal Uplift and Volcanism     

Patrizia Mariani  Carla Braitenberg  Fabrizio Antonioli 《Pure and Applied Geophysics》2009,166(8-9):1369-1402

The low variability of MIS 5.5 sea level (M.I.S = Marine Isotopic Stage) with respect to the present day sea level, allows the Sardinian coast to be used as an eustatic reference for the entire Mediterranean region. This level is generally at 7 ± 2 m above current sea level along the Sardinian coast. One sector along the Orosei Gulf (eastern Sardinia) includes a characteristic and well conserved tidal notch that changes in elevation from 7.6 to 11.5 m over only 30 km, tilting upwards towards the north. Generally, height deviations of such a tidal notch would be due to tectonic or volcanic activity. The Sardinia coast however, is considered to have too little tectonic activity, and also too small post-glacial rebound in order to explain the anomaly. The remaining possibility is Neogene-Quaternary continental and/or submarine volcanic activity, which we investigate as a possible cause for the observed anomalies. In this paper, our goal is to explain the anomaly by modelling recent volcanic loading or updoming related to magmatic intrusion emplacement. We review the literature on the recent volcanic deposits, both on-shore and off-shore, and investigate to what extent volcanic loads can influence the coastline from a theoretical standpoint, using the isostatic flexure model and a range of loads. We find that the observed notch height anomaly cannot be explained by volcanic loading, but must be produced by an upward welling due to the emplacement of volcanic material, as produced for instance by a laccolith or batholith. The upward movement could be related to the submarine volcano only recently detected, or to a source located on the eastern Sardinia coast near Orosei.  相似文献   

Behavioural responses of the mangrove fiddler crabs (Ucaannulipes and U. inversa) to urban sewage loadings: Results of a mesocosm approach     

Fabrizio Bartolini  Gil Penha-Lopes  Samwel Limbu  José Paula  Stefano Cannicci 《Marine pollution bulletin》2009,58(12):1860-1867

The study aimed at investigating the effects of sewage loadings on the behaviour of two fiddler crabs species maintained in a system of experimental mesocosms, built in a mangrove area in Tanzania and inundated with different seawater/sewage mixtures. Our results show that sewage loads led to a modification of the overall activity budget of the crab community as a result of increased hypertrophic conditions (high COD, increased chlorophyll-a concentrations). During their activity period, crabs inside contaminated mesocosms seemed to satisfy their feeding demand faster than those of the control cells, spending a significant longer time in other activities like courtship and territorial defence. Apart from being a good biological indication of ecosystem eutrophication, such a reduced foraging activity by fiddler crabs also depresses their sediment bioturbation activity, important factor for the health of mangrove systems, suggesting practical implications regarding the efficiency of mangrove-based wetlands for treatment of domestic sewage.  相似文献   

Time-dependent geochemistry of clinopyroxene from the Alban Hills (Central Italy): Clues to the source and evolution of ultrapotassic magmas     

Mario Gaeta  Carmela Freda  John N. Christensen  Luigi Dallai  Fabrizio Marra  Daniel B. Karner  Piergiorgio Scarlato 《Lithos》2006,86(3-4):330-346

We investigated chemical and isotopic compositions of clinopyroxene crystals from well age-constrained juvenile scoria clasts, lava flows, and hypoabyssal magmatic ejecta representative of the whole eruptive history of the Alban Hills Volcanic District. The Alban Hills is a Quaternary ultra-potassic district that was emplaced into thick limestone units along the Tyrrhenian margin of Italy. Alban Hills volcanic products, even the most differentiated, are characterised by low SiO₂ content. We suggest that the low silica activity in evolving magmas can be ultimately due to a decarbonation process occurring at the magma/limestone interface. According to the liquid line of descent we propose, the differentiation process is driven by crystallisation of clinopyroxene + leucite ± apatite ± magnetite coupled with assimilation of a small amount of calcite and/or with interaction with crustal CO₂. By combining age, chemical data, strontium and oxygen isotopic compositions, and REE content of clinopyroxene, we give insights into the evolution of primitive ultrapotassic magmas of the Alban Hills Volcanic District over an elapsed period of about 600 kyr. Geochemical features of clinopyroxene crystals, consistent with data coming from other Italian ultrapotassic magmas, indicate that Alban Hills primary magmas were generated from a metasomatized lithospheric mantle source. In addition, our study shows that the ⁸⁷Sr / ⁸⁶Sr and LREE/HREE of Alban Hills magmas continuously diminished during the 600–35 ka time interval of the Alban Hills eruptive history, possibly reflecting the progressive depletion of the metasomatized mantle source of magmas.  相似文献   

Presence of plastic debris in loggerhead turtle stranded along the Tuscany coasts of the Pelagos Sanctuary for Mediterranean Marine Mammals (Italy)     

Tommaso Campani  Matteo Baini  Matteo Giannetti  Fabrizio Cancelli  Cecilia Mancusi  Fabrizio Serena  Letizia Marsili  Silvia Casini  Maria Cristina Fossi 《Marine pollution bulletin》2013

This work evaluated the presence and the frequency of occurrence of marine litter in the gastrointestinal tract of 31 Caretta caretta found stranded or accidentally bycaught in the North Tyrrhenian Sea. Marine debris were present in 71% of specimens and were subdivided in different categories according to Fulmar Protocol (OSPAR 2008). The main type of marine debris found was user plastic, with the main occurrence of sheetlike user plastic. The small juveniles showed a mean ± SD of marine debris items of 19.00 ± 23.84, while the adult specimens showed higher values of marine litter if compared with the juveniles (26.87 ± 35.85). The occurrence of marine debris observed in this work confirms the high impact of marine debris in the Mediterranean Sea in respect to other seas and oceans, and highlights the importance of Caretta caretta as good indicator for marine litter in the Marine Strategy Framework Directive (MSFD) of European Union.  相似文献   

Influence of the Po River runoff on the bacterioplankton community along trophic and salinity gradients in the Northern Adriatic Sea          下载免费PDF全文

Ilaria Pizzetti  Giuliano Lupini  Fabrizio Bernardi Aubry  Francesco Acri  Bernhard M. Fuchs  Stefano Fazi 《Marine Ecology》2016,37(6):1386-1397

The Po River runoff strongly affects the oceanographic and ecological characteristics of the Northern Adriatic Sea. Catalysed reported deposition ‐ fluorescence in situ hybridization (CARD‐FISH) analysis was employed to assess how the composition of the coastal bacterioplankton community is influenced by the river runoff in two different seasons (spring and autumn). Samples were collected from the water column along a coastal–offshore transect in the Northern Adriatic Sea at different depths. Four clone libraries were then constructed from coastal (0 m) and offshore waters (?65 m). Higher abundances of bacteria were recorded in coastal waters as compared with the offshore samples. This result was mainly due to the trophic state of the water column, and it was related to salinity. Particularly, Actinobacteria and Gammaproteobacteria were affected by the riverine inputs, whereas Bacteroidetes and Alphaproteobacteria showed only minor responses. This was particularly clear in the autumn sample, in which a clear difference between the coastal and the offshore samples was found due to a strong influence of the less saline river water with high nutrient concentrations. Analysis of 205 partial length 16S rRNA gene sequences indicated a high diversity with the dominance of Alphaproteobacteria, Bacteroidetes and Gammaproteobacteria mainly affiliated to coastal and marine bacterioplankton clades. Actinobacteria were also detected and, together with Gammaproteobacteria, strongly follow the freshwater intrusion. Overall, our results indicate that the seasonal difference in the Po River discharge greatly affects the bacterioplankton community. In spring we observed a smooth transition from coastal to open‐sea conditions owing to the more superficial freshwater plume. In autumn the deeper freshwater intrusion in the coastal site and thermal stratification offshore resulted in a marked difference between the coastal and offshore microbial communities.  相似文献   

Connectivity and single/dual domain transport models: tests on a point-bar/channel aquifer analogue     

Diana Dell’Arciprete  Chiara Vassena  Fulvia Baratelli  Mauro Giudici  Riccardo Bersezio  Fabrizio Felletti 《Hydrogeology Journal》2014,22(4):761-778

In porous aquifers, groundwater flow and solute transport strongly depend on the sedimentary facies distribution at fine scale, which determines the heterogeneity of the conductivity field; in particular, connected permeable sediments could form preferential flow paths. Therefore, properly defined statistics, e.g. total and intrinsic facies connectivity, should be correlated with transport features. In order to improve the assessment of the relevance of this relationship, some tests are conducted on two ensembles of equiprobable realizations, obtained with two different geostatistical simulation methods—sequential indicator simulation and multiple point simulation (MPS)—from the same dataset, which refers to an aquifer analogue of sediments deposited in a fluvial point-bar/channel association. The ensembles show different features; simulations with MPS are more structured and characterised by preferential flow paths. This is confirmed by the analysis of transport connectivities and by the interpretation of data from numerical experiments of conservative solute transport with single and dual domain models. The use of two ensembles permits (1) previous results obtained for single realizations to be consolidated on a more firm statistical basis and (2) the application of principal component analysis to assess which quantities are statistically the most relevant for the relationship between connectivity indicators and flow and transport properties.  相似文献   

The Monte Orfano Conglomerate revisited: stratigraphic constraints on Cenozoic tectonic uplift of the Southern Alps (Lombardy, northern Italy)   总被引：1，自引：0，他引：1  

Dario Sciunnach  Giancarlo Scardia  Fabrizio Tremolada  Isabella Premoli Silva 《International Journal of Earth Sciences》2010,99(6):1335-1355

The Monte Orfano Conglomerate (MOC), exposed in the foothills of the Southern Alps (northern Italy), is one of the few outcrops of sediments documenting the Cenozoic tectonic evolution of the Alpine retrowedge. Calcareous nannofossil biostratigraphy allowed us to constrain the upper part of the MOC, formerly attributed to the Early-Middle Miocene in the type-locality, to the earliest Miocene (Neogene part of the NN1 nannofossil zone). A likely latest Oligocene age is therefore suggested for the bulk of the underlying conglomerates, whose base is not exposed. Deposition of the MOC can be placed within the post-collisional tectonic uplift of the Alps, documented in the Lake Como area by the Como Conglomerate (CC) at the base of the Gonfolite Lombarda Group, and supports the correlation with Upper Oligocene clastic sediments cropping out further to the East, in the Lake Garda and in the Veneto-Friuli areas (“molassa”). The remarkable difference in petrographic composition between the western (CC) and eastern (MOC) clastics deposited in the Alpine retro-foreland basin highlights the synchronous tectonic activity of two structural domains involving different crustal levels. Whilst the bulk of the CC, that straddles the Oligocene/Miocene boundary, records largely the tectonic exhumation of the Alpine axial chain crystalline complexes, the coeval MOC consists of detritus derived from the superficial crustal section (Triassic to Paleogene sedimentary rocks) of the Alpine retrowedge and constrains the onset of the post-collisional deformation phase of the Southern Alps as not younger than the Late Oligocene.  相似文献