SV Kommandor Jack Cruise 01/05, 11 Jul – 08 Aug 2005. Multibeam bathymetry and high resolution sidescan sonar surveys within the SEA7 area of the UK continental shelf

The objectives of the SV Kommandor Jack 01/05 cruise were to collect EM120, and where water depths permit, EM1002 multibeam bathymetry and backscatter data, and also where desired, high resolution sidescan sonar data, over Anton Dohrn Seamount, George Bligh and Rosemary Banks, the eastern margin of Rockall Bank and selected areas of Hatton Bank. The aims were to a) create high quality bathymetric maps of the survey areas b) create acoustic backscatter maps over the same areas c) when possible, define the extent of any potential coral habitats d) create high resolution bathymetric, backscatter and sonar maps of specific features as may be discovered, such as mud diapers, carbonate mounds etc. e) complete, during the cruise, a preliminary interpretation of the above data, to be used as a guide for the sampling and seabed photography cruise which followed immediately. This was a highly successful cruise with virtually all cruise objectives achieved. 6,384 line-km of multibeam bathymetry and backscatter data were obtained in water depths between 150 and 2,400 m. In addition, approximately 240 line-km of high resolution sidescan sonar were collected in depths between 150 and 1,500 m, and 6,323 line-km of high resolution CHIRP profiles were also collected

SV Kommandor Jack Cruise 01/05, 11 Jul – 08 Aug 2005. Multibeam bathymetry and high resolution sidescan sonar surveys within the SEA7 area of the UK continental shelf

The objectives of the SV Kommandor Jack 01/05 cruise were to collect EM120, and where water depths permit, EM1002 multibeam bathymetry and backscatter data, and also where desired, high resolution sidescan sonar data, over Anton Dohrn Seamount, George Bligh and Rosemary Banks, the eastern margin of Rockall Bank and selected areas of Hatton Bank. The aims were toa) create high quality bathymetric maps of the survey areasb) create acoustic backscatter maps over the same areasc) when possible, define the extent of any potential coral habitatsd) create high resolution bathymetric, backscatter and sonar maps of specific features as may be discovered, such as mud diapers, carbonate mounds etc.e) complete, during the cruise, a preliminary interpretation of the above data, to be used as a guide for the sampling and seabed photography cruise which followed immediately.This was a highly successful cruise with virtually all cruise objectives achieved. 6,384 line-km of multibeam bathymetry and backscatter data were obtained in water depths between 150 and 2,400 m. In addition, approximately 240 line-km of high resolution sidescan sonar were collected in depths between 150 and 1,500 m, and 6,323 line-km of high resolution CHIRP profiles were also collected

Ephemeral rollover points and clinothem evolution in the modern Po Delta based on repeated bathymetric surveys

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Micromorphology of diamicton affected by iceberg-keel scouring, Scoresby Sund, East Greenland

Icebergs are important as agents of deposition and seafloor reworking on glacier-influenced continental margins. When the keel of an iceberg exceeds water depth it ploughs through soft sediments producing scours/ploughmarks that can be kilometres long, hundreds of metres wide and sometimes tens of metres deep. Because the influence of iceberg keels on sediment is a critical factor when offshore structures (e.g. pipelines, power cables) are installed, the surface morphology of iceberg scours on the seafloor is relatively well-documented. Less however, is known about sub-scour deformation below the seafloor. This is particularly true of iceberg scoured diamicton (poorly sorted sediment comprising a variety of particle sizes), which is present in many high-latitude fjords and continental shelves. The aim of this research is to examine directly (macroscopically and microscopically, with thin sections) the style and intensity of deformation caused by the scouring action of iceberg keels in diamicton offshore of East Greenland. Results show that a distinctive suite of deformation structures (individual structures and overprinted structural patterns) dominated by planar shear, sediment mixing and high porewater, and dropstones characterises iceberg scoured diamicton. In addition, diamicton from areas of high-intensity iceberg scouring tends to show a wider variety, higher frequency and distribution, more abundant and better-developed deformation structures than diamicton from areas of intermediate- and low-intensity iceberg scouring. Characterising the effects of iceberg scour in diamicton is important more widely to inform: i) reconstruction of the geometry and dynamics of former ice sheets; and ii) installation and protection of offshore engineering structures in diamicton where iceberg scouring presents a geohazard. The value of micromorphology is significant especially in the absence of macroscopic sediment exposures/outcrops where the study of cores is necessary instead.This research was primarily funded by the University of Brighton's ‘Rising Stars Initiative’ and the ‘School of Environment and Technology Research Investment Fund’, with supplementary funds awarded by the Quaternary Research Association. The funding sources had no involvement in study design, in collection, analysis and interpretation of data, in the writing of the article and in the decision to submit the article for publication

Sediment circulation in mixed gravel and shingle bayhead beaches on the South East Dorset coast.

This thesis investigates and attempts to clarify the morphological characteristics, processes and sedimentology of five local mixed gravel and shingle beaches. A conceptual framework of process response has been adopted which considers energy inputs, sediment transport and coastal morphology, under conditions of limited sediment supply and a "closed cell" situation. Onshore field investigations using conventional methods of surface sediment sampling, together with beach profiling, platform and cliff measurements provided quantitative data with respect to contemporary sediment inputs, sediment characteristics and transport. Extensive and intensive measurements of beach sections described spatial and temporal morphological and volumetric change and revealed a neutral sediment budget at the scale of 12-14 months. The beaches are in equilibrium with prevailing and dominant south westerly wave regimes; prolonged periods of south easterly wave climates influence the foci of wave energy and cause significant littoral drift and exposure of the chalk platform. The offshore data used were derived from available sources and supplemented by fieldwork by the author. Investigations in the nearshore zone by side-scan sonar and echosounder revealed the morphological and sedimentological nature of the seafloor along the northern shore of Weymouth Bay. Sediment distribution and bedforms suggested preferred sediment transport paths. Within each bay sediment sampling by grab and/or divers elucidated the nature of each sediment cell. The distinct differences of textural composition and the presence of natural offshore barriers to sediment movement highlighted the sedimentological/morphological containment of each bayhead unit. Theoretical considerations and field data have helped to gain a better understanding of the relationship between cliff, beach, platform and nearshore processes and illustrate that selected embayments along the northern shore of Weymouth Bay are morphologically contained sediment cells sharing the same hydrodynamic system

Postglacial (after 18 ka) deep-sea sedimentation along the Hikurangi subduction margin (New Zealand): Characterisation, timing and origin of turbidites

International audienceRecent sedimentation along the Hikurangi subduction margin off northeastern New Zealand is investigated using a series of piston cores collected between 2003 and 2008. The active Hikurangi Margin lies along the Pacific-Australia subduction plate boundary and contains a diverse range of geomorphologic settings. Slope basin stratigraphy is thick and complex, resulting from sustained high rates of sedimentation from adjacent muddy rivers throughout the Quaternary. Turbidites deposited since c. 18 ka in the Poverty, Ruatoria and Matakaoa re-entrants are central to this study in that they provide a detailed record of the past climatic conditions and tectonic activity. Here, alternating hemipelagite, turbidite, debrite and tephra layers reflect distinctive depositional modes of marine sedimentation, turbidity current, debris flow and volcanic eruption, respectively. Turbidites dominate the record, ranging in lithofacies from muddy to sandy turbidites, and include some basal-reverse graded turbidites inferred to be derived from hyperpycnal flows. Stacked turbidites are common and indicate multiple gravity-flows over short time periods. The chronology of turbidites is determined by collating an extremely dense set of radiocarbon ages and dated tephra, which facilitate sedimentation rate calculation and identification of the origin of turbidites. Sedimentation rates range from 285 cm/ka during late glacial time (18.5-17 ka) to 15 to 109 cm/ka during postglacial time (17-0 ka). Turbidite deposition is controlled by: (1) the emplacement of slope avalanches reorganising sediment pathways; (2) the postglacial marine transgression leading to a five-fold reduction in sediment supply to the slope due to disconnection of river mouths from the shelf edge, and (3) the Holocene/ Pleistocene boundary climate warming resulting in a drastic decrease in the average turbidite grain-size. Flood-induced turbidites are scarce: nine hyperpycnites are recognised since 18 ka and the youngest is correlated to the largest ENSO-related storm event recorded onland (Lake Tutira). Other turbidites contain a benthic foraminiferal assemblage which is strictly reworked from the upper slope and which relates to large earthquakes over the last c. 7 ka. They yield a shorter return time (270-430 years) than the published coastal records for large earthquakes (c. 670 years), but the offshore record is likely to be more complete. The deep-sea sedimentation along the New Zealand active margin illustrates the complex interaction of tectonic and climate in turbidite generation. Climate warming and glacio-eustatic fluctuations are well recorded at a millennial timescale (18 ka), while tectonic deformation and earthquakes appear predominant in fostering turbidite production at a centennial timescale (270-430 years)