Search results for "continental shelf"
showing 8 items of 68 documents
On the formation of laminated sediments on the continental margin off Pakistan: the effects of sediment provenance and sediment redistribution
2001
Abstract The sedimentary processes and sediment sources contributing to the formation of laminated sediments along the upper slope off Pakistan are unravelled using inorganic bulk sediment geochemistry of 43 surface cores from the Pakistani continental margin and additional geochemical and Pb and Nd-isotope data for different types of layers. An important process everywhere along the margin is redeposition of fluvial-derived detritus from the shelf onto the slope. This process is of considerably higher intensity along the Makran margin than on the Indus margin. Trace element enrichment related to early diagenesis or surface productivity, which is commonly detectable in bulk sediment composi…
Pattern and rate of post-20 ka vertical tectonic motion around the Capo Vaticano Promontory (W Calabria, Italy) based on offshore geomorphological in…
2014
The magnitude and rate of Late Pleistocene-Holocene vertical tectonic movements offshore of the Capo Vaticano Promontory (western Calabria, southern Italy) have been measured on the basis of the present-day depth variations of the edges of submerged depositional terraces (and associated abrasion platforms) that formed below the storm-wave base, during the sea level stillstand of the Last Glacial Maximum (LGM). These depositional features, represented by submerged prograding wedges and an associated terrace-shaped upper boundary, have been identified in high-resolution seismic reflection profiles acquired along the continental shelf and the upper slope of the promontory, and are referred to …
Plio-Pleistocene geological evolution of the northern Sicily continental margin (southern Tyrrhenian Sea): new insights from high-resolution, multi-e…
2003
High-resolution seismic profiles were acquired in the north Sicily offshore region with an innovative, multi-tip sparker array which lacks ringing and has a base frequency around 600 Hz. The new data, combined with published data, suggest that intra-slope and extensional basins formed as a consequence of the late Miocene (?)–early Pliocene shortening and thrusting, and the middle (?)–late Pliocene continental rifting affecting the internal side of the Sicilian-Maghrebian chain. Early (?) Pleistocene to Holocene high-amplitude and high-frequency sea-level changes resulted in repeated sub-aerial exposure and flooding of the shelf, and the deposition of cyclically arranged hemipelagic and shel…
Impact of Holocene tsunamis detected in lagoonal environments on Corfu (Ionian Islands, Greece): Geomorphological, sedimentary and microfaunal eviden…
2016
Abstract In this paper, we present for the first time geomorphological, sedimentary and microfaunal evidence of palaeotsunami impact on Corfu (Ionian Islands, Greece). The island of Corfu is located in an area of exceptional tectonic stress: towards the south, the African oceanic plate is being subducted underneath the Aegean plate, whereas towards the north, the Adriatic and European plates form a continental collision zone. Recent publications provide evidence of earthquake related co-seismic movements that potentially trigger extreme wave events as well as relative sea level fluctuations. In this context, we investigated two selected near-coast geological archives – the Chalikiopoulou La…
Fluid escape structures in the north Sicily continental margin
2014
Abstract High resolution and multichannel seismic profiles coupled with multibeam echosounder (seafloor relief) data, acquired along the northern Sicily continental margin (southern Tyrrhenian Sea), document the occurrence of mound and pockmark features, revealing fluid escape processes. Along this margin, morphology of the high-gradient continental slope is irregular due to the presence of structural highs, slope failures and canyons, and is interrupted by flat areas at a mean depth of 1500 m. Seismostratigraphic analysis tools and methods were used to identify fluid escape structures and to work out a classification on the basis of their morpho-acoustic characteristics. The detailed 3D ba…
Distribution and spatial structure of pelagic fish schools in relation to the nature of the seabed in the Sicily Channel (Central Mediterranean).
2009
Hydroacoustic data collected during two echosurveys carried out in the Sicily Channel in 1998 and 2002 were analysed to investigate the distribution and spatial structure of small pelagic fish species in relation to the sedimentological nature of the sea bottom. The study was carried out on two contiguous areas (labelled ZONE 1 and ZONE 2) of the continental shelf off the southern coast of Sicily, characterised by different dominant texture, ‘sand’ for ZONE 1 and ‘clayey-silt’ for ZONE 2. Simultaneous information on small pelagic fish schools and the seabed was obtained using a quantitative echo-sounder (SIMRAD EK500) that measures echoes due to the scattering from both fish schools and the…
A high resolution record of the last deglaciation in the southern Tyrrhenian Sea: environmental and climatic evolution.
2002
A multidisciplinary study was carried out on core C106 collected in the Salerno Gulf (southern Tyrrhenian Sea). Two tephra layers recovered in the core, N 18 O record of Globigerinoides ruber and Globigerina bulloides and seven 14 C calibrated ages provided the stratigraphic framework. The core sediments cover the last 28 kyr BP. Seismostratigraphic analysis of a high resolution acoustic profile, integrated by the dated core samples, allowed us to reconstruct the architecture and age of sedimentary bodies on the continental shelf. An integrated study based on different taxonomic groups (nannofossils, pteropods, foraminifera, and palynomorphs) provided palaeoclimatic trends, in agreement wit…
First Evidence of Contourite Drifts in the North-Western Sicilian Active Continental Margin (Southern Tyrrhenian Sea)
2021
We present the results of an integrated geomorphological and seismo-stratigraphic study based on high resolution marine data acquired in the north-western Sicilian continental margin. We document for the first time five contourite drifts (marked as EM1a, EM2b, EM2, EM3a, and EM3b), located in the continental slope at depths between ca. 400 and 1500 m. EM1a,b have been interpreted as elongated mounded drifts. EM1a,b are ca. 3 km long, 1.3 km wide, and have a maximum thickness of 36 m in their center that thins northwards, while EM1b is smaller with a thickness up to 24 m. They are internally characterized by mounded seismic packages dominated by continuous and parallel reflectors. EM2 is loc…