Papers by Daniela Accettella
Marine and Petroleum Geology
EGU General Assembly Conference Abstracts, Apr 1, 2018
34th International Association of Sedimentologists (IAS) Meeting of Sedimentology, Sedimentology ... more 34th International Association of Sedimentologists (IAS) Meeting of Sedimentology, Sedimentology to face societal challenges on risk, resources and record of the past, 10-13 September 2019, Rom
Rui, L. ... et. al.-- Final Conference ARCA PROJECT : ARctic: present Climatic change and pAst ex... more Rui, L. ... et. al.-- Final Conference ARCA PROJECT : ARctic: present Climatic change and pAst extreme events, 11 October, 2016, Rome.-- 3 pages, 3 figures
Geomorphology, 2021
Increased ocean heat supply to the Antarctic continental shelves is projected to cause accelerate... more Increased ocean heat supply to the Antarctic continental shelves is projected to cause accelerated ice sheet loss and contribute significantly to global sea-level rise over coming decades. Changes in temperature or salinity of dense shelf waters around Antarctica, resulting from increased glacial meltwater input, have the potential to significantly impact the location and structure of the global Meridional Overturning Circulation, with seabed irregularities such as submarine canyons, driving these flows toward the abyss. Submarine canyons also influence the location of intruding warm water currents by acting as preferential routes for rising Circumpolar Deep Water. These global changes have implications for large-scale effects to atmospheric and oceanic circulation. The ability for numerical modellers to predict these future behaviours is dependent upon our ability to understand both modern and past oceanic, sedimentological and glaciological processes. This knowledge allows ocean models to better predict the flux and pathways of Circumpolar Deep Water delivery to the shelf, and consequently to ice shelf cavities where melt is concentrated. Here we seek to understand how dense shelf water and other continental slope processes influence submarine canyon morphology by analysing newly Accepted 28th September 2020 2 collected geophysical and oceanographic data from a region of significant and prolonged dense shelf water export, the Hillary Canyon in the Ross Sea. We find that cascading flows of dense shelf water do not contribute to significant gully incision at the shelf edge during interglacial periods, however, are strong enough to prevent gully infilling and contribute to canyon-levee aggradation down-slope. We find buried paleo-gullies beneath gullies incising the modern seafloor. Paleo-gullies occur as single gullies and in complexes indicating that gully activity was continuous over multiple glacial cycles and formed an important role in the development of the shelf edge and upper slope. Glacial cycles likely drive large-scale shifts in canyon head processes with periods of intense seafloor erosion and significant gully incision likely occurring when ice grounded near to the shelf edge, during glacial and deglacial periods, when sediment-laden subglacial meltwater was released at the shelf edge. We put slope morphology observed at the Hillary Canyon head into global perspective to show that cascading flows of dense shelf water do not exert consistent patterns of erosion on high-latitude continental margins. 2. Introduction Increased ocean heat supply to Antarctic continental shelves is projected to cause accelerated ice sheet loss and contribute significantly to global sea-level rise over coming decades to centuries (De Conto et al., 2016; IPCC, 2019). Currently, numerical modelling studies lack necessary resolution and spatial coverage of seafloor morphology data to sufficiently constrain past and future sub-ice shelf melting, ice-sheet collapse, and sea level change estimates (Petrini et al., 2018; Colleoni et al., 2018). This is because one of the major causes of current Antarctic ice sheet retreat stems from increased ocean heat supply to the continental shelves surrounding Antarctica, with atmospheric temperature rise contributing to a lesser extent (Rignot et al., 2019; IPCC, 2019). Recent studies show that heat and volume transport around Antarctica are substantially enhanced where seafloor irregularities, such as submarine canyons, allow dense shelf waters to descend down-slope (Morrison et al., 2020). Warm water incursions onto the shelf can be intermittent and highly localised and can vary depending on the geometry of the ice shelf and seafloor bathymetry (Padman et al., 2018). Lack of necessary resolution and data availability to image these irregularities therefore makes predictions and future estimates of ice sheet and oceanic changes difficult. Thinning of ice shelves, due to increasing ocean temperatures and warm water incursions can lead to rapid ice retreat. This is especially true where marine based ice-sheets occur in conjunction with a landward sloping seabed, seen around the West and East Antarctic Ice Sheet (WAIS and
Deep Sea Research Part I: Oceanographic Research Papers, 2021
Eos, 2018
A team of polar scientists aboard the OGS Explora, cruising in rare ice-free conditions, discover... more A team of polar scientists aboard the OGS Explora, cruising in rare ice-free conditions, discovered new evidence of ancient and modern-day ice sheet sensitivity to climatic fluctuations.
arktos, 2019
The INBIS (Interfan Bear Island and Storfjorden) Channel System is a rare example of a deep-sea c... more The INBIS (Interfan Bear Island and Storfjorden) Channel System is a rare example of a deep-sea channel on a 14 glaciated margin. The system is located between two Trough Mouth Fans (TMFs) on the continental slope of the 15 NW Barents Sea: the Bear Island and the Storfjorden-Kveithola TMFs. New bathymetric data in the upper part of this channel system shows a series of gullies that incise the shelf break and minor tributary channels on the 17 upper part of the continental slope. These gullies and channels appears far more developed than those on the rest 18 of the NW Barents Sea margin, increasing in size downslope and eventually merging into the INBIS Channel. 19 Morphological evidence suggests that the Northern part of the INBIS Channel System preserved its original 20 morphology over the Last Glacial Maximum (LGM), whereas the Southern part experienced the emplacement 21 of mass-transport glacigenic debris that obliterated the original morphology. Radiometric analyses were applied 22 on two sediment cores to estimate the recent (~ 110 years) sedimentation rates. Furthermore, analysis of grain 23 size characteristics and sediment composition of two cores shows evidence of turbidity currents. We associate 24 these turbidity currents with density-driven plumes, linked to the release of meltwater at the ice-sheet grounding 25 line, cascading down the slope. This type of density current would contribute to the erosion and/ or preservation 26 of the gullies' morphologies during the present interglacial. We infer that Bear Island and the shallow 27 morphology around it prevented the flow of ice streams to the shelf edge in this area, working as a pin (fastener) 28 for the surrounding ice and allowing for the development of the INBIS Channel System on the inter-ice stream 29 part of the slope. The INBIS Channel System was protected from the burial by high rates of ice-stream derived 30 sedimentation and only partially affected by the local emplacement of glacial debris, which instead dominated 31 on the neighbouring TMF systems. 32 1. Introduction 33 Reconstruction of paleo-ice stream behaviour on a high-latitude glaciated continental margin is possible through 34 the analysis of the associated characteristic features in the sedimentological and geomorphological record 35 (Stokes & Clark, 2001). The most prominent features related to the activity of ice streams are the Trough Mouth 36 Fans (TMFs). These are prograding fan-shaped sediment wedges are formed by glacigenic debris flows 37 discharged by paleo-ice streams (Vorren et al., 1989). Gullies are small V-shaped erosional features that dissect 38 the shelf edge and upper continental slope (
Geomorphology, 2018
Carbonate escarpments are submarine limestone and dolomite cliffs that have been documented in nu... more Carbonate escarpments are submarine limestone and dolomite cliffs that have been documented in numerous sites around the world. Their geomorphic evolution is poorly understood due to difficulties in assessing escarpment outcrops and the limited resolution achieved by geophysical techniques across their steep topographies. The geomorphic evolution of carbonate escarpments in the Mediterranean Sea has been influenced by the Messinian salinity crisis (MSC). During the MSC (5.97-5.33 Ma), the Mediterranean Sea became a saline basin due to a temporary restriction of the Atlantic-Mediterranean seaway, resulting in the deposition of more than one million cubic kilometres of salt. The extent and relative chronology of the evaporative drawdown phases associated to the MSC remain poorly constrained. In this paper we combine geophysical and sedimentological data from the central Mediterranean Sea to reconstruct the geomorphic evolution of the Malta Escarpment and infer the extent and timing of evaporative drawdown in the eastern Mediterranean Sea during the MSC. We propose that, during a MSC base-level fall, fluvial erosion formed a dense network of canyons across the Malta Escarpment whilst coastal erosion developed extensive palaeoshorelines and shore platforms. The drivers of geomorphic evolution of the Malta Escarpment after the MSC include: (i) canyon erosion by submarine gravity flows, with the most recent activity taking place <2600 cal. years BP; (ii) deposition by bottom currents across the entire depth range of the Malta Escarpment; (iii) tectonic deformation in the southern Malta Escarpment in association with a wrench zone; (iv) widespread, small-scale sedimentary slope failures preconditioned by oversteepening and loss of support due to canyon erosion, and triggered by earthquakes. 3 We carry out an isostatic restoration of the palaeoshorelines and shore platforms on the northern Malta Escarpment to infer an evaporative drawdown of 1800-2000 m in the eastern Mediterranean Sea during the MSC. We interpret the occurrence of pre-evaporite sedimentary lobes in the western Ionian Basin as suggesting that either evaporative drawdown and canyon formation predominantly occurred before salt deposition, or that only the latest salt deposition at the basin margin occurred after the formation of the sedimentary lobes.
Geological Society, London, Memoirs, 2016
Extensive multibeam mapping and sub-seafloor data from multichannel reflection-seismic surveys hi... more Extensive multibeam mapping and sub-seafloor data from multichannel reflection-seismic surveys highlight the main morphological characteristics on the continental slope and rise of the western margin of the Antarctic Peninsula. These data provide evidence for several types of Neogene and Quaternary seafloor instability. This continental margin is atypical in its Cenozoic tectonic and sedimentary evolution because it changed from active to passive and sedimentation underwent a transition from river-dominated to glacial-dominated as the Antarctic Ice Sheet began to form (Eocene–Oligocene). The modern morphology of continental rise is characterized by the presence of sediment mounds, interpreted as sediment drifts orientated perpendicular to the margin. The drifts exhibit common features: they are located between shelf lobes and display a steep flank towards the SW and a gentle flank towards the NE. Despite the steepness of the slope, sediment failures occur mainly on the continental rise (Volpi et al. 2011). The morphology of the western margin of the Antarctic Peninsula is influenced by the activity of the ice sheet that guided its sedimentary evolution. The continental slope averages 13° with erosional gullies affecting the upper slope (Fig. 1b, d), but with little evidence of major incisions such as channels, canyons or slide scars (Fig. 1a). However, the …
Geological Society, London, Memoirs, 2016
Trough-mouth fans (TMFs; e.g. Vorren et al. 1989) are seaward-convex sedimentary depocentres comp... more Trough-mouth fans (TMFs; e.g. Vorren et al. 1989) are seaward-convex sedimentary depocentres composed of alternating prograding and aggrading sequences derived primarily from the accumulation of glacigenic debris-flows. In addition, sedimentation may come from contour currents, settling from subglacial meltwater plumes (Taylor et al. 2002) and repeated events of sediment mass transport (Hjelstuen et al. 2007). Ice streams hosted in the glacial troughs are the main mechanism of glacial sediment erosion and transport to the shelf edge during lowstands of sea level at glacial maxima. Glacigenic debris-flow deposition is focused at the front of glacial troughs (e.g. Laberg & Vorren 1995, 1996). The Storfjorden TMF (Fig. 1a) shows a seaward-convex depocentre described by Pedrosa et al. (2011) and Lucchi et al. (2013). The overall bathymetry shows that the outer part of Storfjorden Trough comprises three large depressions separated by shallower banks (Fig. 1a). The continental shelf edge defines three broad lobes, …
Quaternary Science Reviews, 2016
The Deep-sea & Sub-Seafloor Frontiers Conference project (DS3F), 11-14 March 2012, Sitges, Ba... more The Deep-sea & Sub-Seafloor Frontiers Conference project (DS3F), 11-14 March 2012, Sitges, Barcelona, SpainAt high-latitudes, sediment dynamics and consequent continental margin architecture are deeply affected by grounded ice. Fast-flowing ice streams deliver large quantities of sediments from meltwater plumes and Glacigenic Debris Flows (GDFs) at the mouth of cross-shelf troughs during relatively short time periods (deglaciations and glacial maxima, respectively). Glacigenic sediment dynamics also controls the distribution in time and space of large-scale landslidesPeer Reviewe
International Journal of Earth Sciences, 2008
Abstract We present the seafloor morphology and shal-low seismic structure of the continental slo... more Abstract We present the seafloor morphology and shal-low seismic structure of the continental slope south-east of the Balearic promontory and of the adjacent Algero-Bale-aric abyssal plain from multibeam and chirp sonar data. The main purpose of this research was to identify ...
Marine Geophysical Research, 2013
Within the central Mediterranean, the northwestern sector of the Sicily Channel is the unique are... more Within the central Mediterranean, the northwestern sector of the Sicily Channel is the unique area where two independent tectonic processes can be analyzed: the building of the Sicilian–Maghrebian Chain occurred in Late Miocene and the continental lithospheric rifting of the northern African margin occurred since Early Pliocene. These two geodynamic processes generated a peculiar structural style that is largely recognizable in the Adventure Plateau. This plateau is the shallowest part of the Sicily Channel, where water depths do not generally exceed 150 m. It hosts several areas of geomorphic relief, which in some cases rise up to less than 20 m beneath sea-level. A series of submarine magmatic manifestations occur in this area, mainly associated with the extensional phase which produced the rift-related depressions of Pantelleria, Malta and Linosa. Seismic-stratigraphic and structural analyses, based on a large set of multichannel seismic reflection profiles and well information acquired mostly for commercial purposes in the 1970s and 1980s, have allowed us to reconstruct the Triassic-Quaternary sedimentary succession of the Adventure Plateau and define its structural setting. A broad lithological distinction can be made between the successions ranging from Triassic to Paleogene, predominantly carbonate, and the successions ranging from Miocene to Quaternary, predominantly siliciclastic. Three main structural belts have been identified within the Adventure Plateau: (1) the northern belt, affected during Late Miocene time by ESE-verging thrusts belonging to the External Thrust System orogenic domain, which represents the lowermost structural level of the Sicilian–Maghrebian Orogen; (2) the Apenninic–Maghrebian domain of the Sicilian–Maghrebian Orogen, which occupies the northwestern sector of the Adventure Plateau, and that is overthrusted on the External Thrust System orogenic domain during the Late Miocene; (3) the extensional belt of the southwestern sector of the Adventure Plateau, affected by broad NW-trending, high-angle normal faults associated with the Early Pliocene continental rifting phase. The eastern boundary of the Adventure Plateau corresponds to a broadly N–S trending lithospheric transfer zone separating two sectors of the Sicily Channel characterized by a different tectonic evolution.
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Papers by Daniela Accettella