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Michele Rebesco - One of the best experts on this subject based on the ideXlab platform.
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Relationship between Continental Rise development and palaeo-ice sheet dynamics, Northern Antarctic Peninsula Pacific margin
Quaternary Science Reviews, 2020Co-Authors: David Amblas, Roger Urgeles, Miquel Canals, Antoni Calafat, Michele Rebesco, Angelo Camerlenghi, Ferran Estrada, Marc De Batist, John E. Hughes-clarkeAbstract:12 pages, 7 figuresAcquisition of swath bathymetry data west of the North Antarctic Peninsula (NAP), between 63°S and 66°S, and its integration with the predicted seafloor topography of Smith and Sandwell [Global seafloor topography from satellite altimetry and ship depth soundings. Science 277, 1956-1962.] reveal the links between the Continental Rise depositional systems and the NAP palaeo-ice sheet dynamics. The NAP Pacific margin consists of a wide Continental shelf dissected by several troughs, tens of kilometres wide and long. The Biscoe Trough, which has been almost entirely surveyed with multibeam sonar, shows spectacular fan-shaped streamlining sea-floor morphologies revealing the presence of ice streams during the Last Glacial Maximum. In the study area the Continental Rise compRises the six northernmost sediment mounds of the NAP Pacific margin and the canyon-channel systems between them. These giant sediment mounds have developed since the early Neogene by southwest flowing bottom currents, which have redistributed along the margin the fine-grained component of the turbiditic currents flowing down canyon-channel systems. The widespread evidence of shallow slope instability within the sediment mounds has been identified from both swath bathymetry and topographic parametric sonar seismic reflection profiles. Bathymetric data show that the heads of all the Rise canyon-channel systems coincide geographically with the mouths of the major glacial troughs on the Continental shelf edge. This suggests a close genetic link between these morphological features and allows considering a glacio-sedimentary model for the western NAP outer margin seascape development. This model considers the availability of depositional space on the Continental Rise as the limiting factor for mound development. The depositional space, in turn, is controlled by the spacing between glacial maxima shelf-edge reaching ice streams. This model takes into account both glacial and interglacial scenarios and gives new insights on evaluating the palaeoenvironmental record of the Continental Rise sediment mounds. © 2005 Elsevier Ltd. All rights reservedThis study was supported by the Spanish (COHIMAR project, ref. REN2000-0896/ANT), Italian and Belgian Antarctic programs, Fullbright Commission GEMARANT project and Generalitat de Catalunya Grant 2001SGR-00076 to excellence research groups. Support from the Spanish ‘‘Ministerio de Educación, Cultura y Deporte’’ (D.A.) and ‘‘Ministerio de Ciencia y Tecnologı´a’’ (R.U.) through FPU and ‘‘Ramon y Cajal’’ fellowships, respectively, is greatly acknowledgedPeer Reviewe
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the present and past bottom current flow regime around the sediment drifts on the Continental Rise west of the antarctic peninsula
Marine Geology, 2008Co-Authors: Clausdieter Hillenbrand, Michele Rebesco, Angelo Camerlenghi, Renata G Lucchi, F J Hernandezmolina, Ellen A. Cowan, Gabriele UenzelmannnebenAbstract:Throughout the last decade large sediment drifts located on the upper Continental Rise west of the Antarctic Peninsula were the target of oceanographic measurements, bathymetric mapping, seismic investigations, shallow sediment coring, and deep-sea drilling by Ocean Drilling Program (ODP) Leg 178. These studies concluded that for most of the late Neogene and Quaternary a generally SW-ward directed bottom current affected the deposition on the drifts. In particular during glacial periods, the deposition was additionally influenced by NW-ward directed transport of terrigenous detritus supplied by turbidity currents from the Antarctic Peninsula Continental slope. In a recent study, however, the palaeomagnetic signal of the drift sediments recovered at two ODP Leg 178 sites (1095 and 1101) was interpreted to provide spatial and directional information on the physical record of the NE-ward flowing Antarctic Circumpolar Current (ACC). Here we investigate the link between the clockwise flowing ACC and the generally SW-wards flowing near-bottom contour current. We show that at the ODP Leg 178 sites on the western Antarctic Peninsula Continental margin the ACC only affects the ocean circulation above ca. 1000 m water depth. Therefore, the signal of ACC flow might only be archived in the ice-rafted debris (IRD) content of the drift sediments. However, the IRD from the Leg 178 sites accounts for only a small proportion of the drift sediments and is dominantly of local origin. Past variability of bottom-water flow around the sediment drifts was reconstructed on the basis of seismic studies and clay mineralogical and grain-size analyses. These reconstructions provide useful information about both downstream direction and velocity changes of the bottom current and point to its SW-ward flow along the upper Rise during at least the last 9.4 Ma.
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relationship between Continental Rise development and palaeo ice sheet dynamics northern antarctic peninsula pacific margin
Quaternary Science Reviews, 2006Co-Authors: David Amblas, Roger Urgeles, Miquel Canals, Antoni Calafat, Michele Rebesco, Angelo Camerlenghi, Ferran Estrada, Marc De Batist, John E HughesclarkeAbstract:Abstract Acquisition of swath bathymetry data west of the North Antarctic Peninsula (NAP), between 63°S and 66°S, and its integration with the predicted seafloor topography of Smith and Sandwell [Global seafloor topography from satellite altimetry and ship depth soundings. Science 277, 1956–1962.] reveal the links between the Continental Rise depositional systems and the NAP palaeo-ice sheet dynamics. The NAP Pacific margin consists of a wide Continental shelf dissected by several troughs, tens of kilometres wide and long. The Biscoe Trough, which has been almost entirely surveyed with multibeam sonar, shows spectacular fan-shaped streamlining sea-floor morphologies revealing the presence of ice streams during the Last Glacial Maximum. In the study area the Continental Rise compRises the six northernmost sediment mounds of the NAP Pacific margin and the canyon-channel systems between them. These giant sediment mounds have developed since the early Neogene by southwest flowing bottom currents, which have redistributed along the margin the fine-grained component of the turbiditic currents flowing down canyon-channel systems. The widespread evidence of shallow slope instability within the sediment mounds has been identified from both swath bathymetry and topographic parametric sonar seismic reflection profiles. Bathymetric data show that the heads of all the Rise canyon-channel systems coincide geographically with the mouths of the major glacial troughs on the Continental shelf edge. This suggests a close genetic link between these morphological features and allows considering a glacio-sedimentary model for the western NAP outer margin seascape development. This model considers the availability of depositional space on the Continental Rise as the limiting factor for mound development. The depositional space, in turn, is controlled by the spacing between glacial maxima shelf-edge reaching ice streams. This model takes into account both glacial and interglacial scenarios and gives new insights on evaluating the palaeoenvironmental record of the Continental Rise sediment mounds.
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variability in cenozoic sedimentation along the Continental Rise of the bellingshausen sea west antarctica
Marine Geology, 2006Co-Authors: Carsten Scheuer, Michele Rebesco, Robert D. Larter, Karsten Gohl, G B UdintsevAbstract:Seismic reflection profiles, bathymetric and magnetic data collected along and across the Continental margin of the Bellingshausen Sea provide new constraints and interpretations of the oceanic basement structure and Cenozoic glacial history of West Antarctica. Evidence for tectonic boundaries that lie perpendicular to the margin has been identified on the basis of one previously unpublished along-slope multichannel seismic reflection profile. By combining several magnetic data sets, we determined basement ages and verified the positions of possible fracture zones, enabling us to improve previous tectonic and stratigraphic models. We establish three main sediment units on the basis of one seismic along-slope profile and by correlation to the Continental shelf via one cross-slope profile. We interpret a lowermost unit, Be3 (older then 9.6 Ma), as representing a long period of slow accumulation of mainly turbiditic sediments. Unit Be2 (from about 9.6 to 5.3 Ma) may represent a period of short-lived ice advances on the Continental shelf. The uppermost unit, Be1 (from about 5.3 Ma to present), apparently consists of rapidly deposited terrigenous sediment that we interpret as having been transported to the shelf edge by frequent advances of grounded ice. Listric faults are observed in Be1 and indicate sediment instability due to interactions between different depositional processes. Correlation of the sediment classification scheme with the Continental Rise of the western Antarctic Peninsula shows obvious differences in sediment depositional patterns. We estimate a very high sedimentation rate for Unit Be1 (up to 295 m/my) which points to an increase in glacial sediment supply due to major glacial outlets that flowed to nearby parts of the shelf edge in Pliocene and Quaternary times. This is in contrast to the situation at the adjacent Antarctic Peninsular margin and many other parts of the Continental Rise around Antarctica.
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terrigenous flux and biogenic silica deposition at the antarctic Continental Rise during the late miocene to early pliocene implications for ice sheet stability and sea ice coverage
Global and Planetary Change, 2005Co-Authors: Jens Grutzner, Clausdieter Hillenbrand, Michele RebescoAbstract:Drift sediments recovered from the East Antarctic Continental Rise at Ocean Drilling Program (ODP) Site 1165 are used to infer variations in East Antarctic Ice Sheet (EAIS) stability and sea ice coverage during the late Miocene and early Pliocene. A significant increase in the deposition of biogenic opal from ~5.8 to 5.2 Ma points to an early Pliocene reduction in sea ice and a subsequent increase in biological productivity. Time intervals at ~7.2 to 6.6 Ma and ~5.2 to 4.8 Ma are characterized by pronounced maxima in the long-term trend of terrigenous matter accumulation (MARter) indicating high Continental erosion rates potentially caused by ice sheet growth. A Southern Ocean wide impact of these events is suggested by similar evidence found at ODP Site 1095 (Antarctic Peninsula). Superimposed on the MARter maxima we observe enhanced orbital variability in iron accumulation at Site 1165 pointing to a dynamic behavior of the EAIS with waxing and waning ice masses. From the concurrence of these high amplitude ice sheet fluctuations with maximum variance in Earth’s obliquity, we propose that the insolation gradient between high and low latitudes affected the delivery of moisture to Antarctica and thus controlled ice volume variations. D 2004 Elsevier B.V. All rights reserved.
Clausdieter Hillenbrand - One of the best experts on this subject based on the ideXlab platform.
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Distribution of clay minerals in drift sediments on the Continental Rise west of the Antarctic Peninsula, ODP Leg 178, Sites 1095 and 1096
2020Co-Authors: Clausdieter Hillenbrand, Werner EhrmannAbstract:The clay mineral compositions of upper Miocene to Quaternary sediments recovered at Ocean Drilling Program (ODP) Leg 178, Sites 1095 and 1096, from the Continental Rise west of the Antarctic Peninsula were analyzed in order to reconstruct the Neogene and Quaternary Antarctic paleoclimate and ice dynamics. The clay mineral assemblages are dominated by smectite, illite, and chlorite. Kaolinite occurs only in trace amounts. Analysis of a surface-sample data set facilitates the assignment of these clay minerals to particular source areas on the Antarctic Peninsula and, thus, the reconstruction of transport pathways. In the ODP cores, clay mineral composition cyclically alternates between two end-member assemblages. One assemblage is characterized by 40% chlorite. The other assemblage has >20% smectite and
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Let’s get to the bottom of West Antarctic Ice Sheet evolution: An initiative to drill sediment drifts on the Amundsen Sea Continental Rise
2015Co-Authors: Gabriele Uenzelmann-neben, Clausdieter HillenbrandAbstract:The Antarctic ice sheets have moved into the focus of public and scientific interest because of modern global warming and their possible contribution to sea level Rise and resulting flooding of low lying coastal areas. Research has predominantly concentrated on recent short-term dynamics of the ice sheets in order to understand their vulnerability to a changing climate by collecting multi-disciplinary data. However, little is known about their long-term evolution, especially about that of the West Antarctic Ice Sheet (WAIS). The WAIS is a marine based ice sheet and assumed to respond more sensitively to both atmospheric and oceanic warming than the largely terrestrial East Antarctic Ice Sheet (EAIS). Information on the early stage of WAIS formation and the Cenozoic glacial history in its Amundsen Sea sector is scarce. Drilling offshore from the George V. and Adelie Land drainage sectors of the EAIS has shown that mid Eocene cooling there was initiated by early flow of the cold Antarctic Counter Current across the Tasman Gateway (IODP Expedition 318). Seismic data indicate that this cold Antarctic Counter Current has also bathed the Amundsen Sea Continental margin implying a cold climate in this area during the Palaeogene. The timing of WAIS formation and possible collapse events thereafter are still under debate, and little is known about the Cenozoic WAIS dynamics in the Amundsen Sea region, where the east setting Antarctic Circumpolar Current (ACC) bathes the Continental Rise. The on-going discussions about the glacial history of West Antarctica resulting from both on- and off-shore studies include topics such as (i) the first appearance of mountain glaciers, ice shelves and local ice caps, (ii) the build up of a large WAIS, (iii) the cooling of surface waters, (iv) the variability of bottom water circulation, and (v) the (in-)stability of the WAIS during the Neogene. Ground truthing is difficult because most of the corresponding palaeo-records were recovered in the Ross Sea sector, thus providing an integrated picture of WAIS and EAIS history, while the only available deep-sea drill site from the Amundsen Sea, DSDP Site 324, extends back to not more than 4 Ma. We suggest the development of an IODP proposal to address the following objectives: 1. Develop a general age-depth model for the whole sedimentary column on the Amundsen Sea Continental Rise down to the oceanic basement, identify its basal age and reconstruct changes in depositional regimes in response to palaeoenvironmental changes from sedimentological analyses on the drill cores 2. Identify the first supply of glaciogenic sediments to the Amundsen Sea for reconstructing WAIS formation 3. Search for indicators for WAIS collapses during the Neogene 4. Identify the oldest documented bottom current activity on the Continental Rise and study its relation to WAIS formation 5. Decipher the history and southward protrusions of Circumpolar Deep Water (CDW) 6. Document the interaction of along-slope and down-slope sediment transport and distinguish between times with high detrital input from the continent and times with low material input for reconstructing ice sheet advance and retreat and changes in bed conditions (temperate vs. polar) on land through time and for determining forcing mechanisms 7. Reconstruct the variability in the direction and velocity of bottom current flow in the Amundsen Sea and infer changes in bottom water production in the source areas (Ross and Weddell seas) We invite and welcome further ideas and contributions.
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the present and past bottom current flow regime around the sediment drifts on the Continental Rise west of the antarctic peninsula
Marine Geology, 2008Co-Authors: Clausdieter Hillenbrand, Michele Rebesco, Angelo Camerlenghi, Renata G Lucchi, F J Hernandezmolina, Ellen A. Cowan, Gabriele UenzelmannnebenAbstract:Throughout the last decade large sediment drifts located on the upper Continental Rise west of the Antarctic Peninsula were the target of oceanographic measurements, bathymetric mapping, seismic investigations, shallow sediment coring, and deep-sea drilling by Ocean Drilling Program (ODP) Leg 178. These studies concluded that for most of the late Neogene and Quaternary a generally SW-ward directed bottom current affected the deposition on the drifts. In particular during glacial periods, the deposition was additionally influenced by NW-ward directed transport of terrigenous detritus supplied by turbidity currents from the Antarctic Peninsula Continental slope. In a recent study, however, the palaeomagnetic signal of the drift sediments recovered at two ODP Leg 178 sites (1095 and 1101) was interpreted to provide spatial and directional information on the physical record of the NE-ward flowing Antarctic Circumpolar Current (ACC). Here we investigate the link between the clockwise flowing ACC and the generally SW-wards flowing near-bottom contour current. We show that at the ODP Leg 178 sites on the western Antarctic Peninsula Continental margin the ACC only affects the ocean circulation above ca. 1000 m water depth. Therefore, the signal of ACC flow might only be archived in the ice-rafted debris (IRD) content of the drift sediments. However, the IRD from the Leg 178 sites accounts for only a small proportion of the drift sediments and is dominantly of local origin. Past variability of bottom-water flow around the sediment drifts was reconstructed on the basis of seismic studies and clay mineralogical and grain-size analyses. These reconstructions provide useful information about both downstream direction and velocity changes of the bottom current and point to its SW-ward flow along the upper Rise during at least the last 9.4 Ma.
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coarse grained terrigenous sediment deposition on Continental Rise drifts a record of plio pleistocene glaciation on the antarctic peninsula
Palaeogeography Palaeoclimatology Palaeoecology, 2008Co-Authors: Ellen A. Cowan, Clausdieter Hillenbrand, Lauren E. HasslerAbstract:Sediment drifts on the Continental Rise are located proximal to the western side of the Antarctic Peninsula and recorded changes in glacial volume and thermal regime over the last ca. 15 m.y. At Ocean Drilling Program (ODP) Site 1101 (Leg 178), which recovered sediments back to 3.1 Ma, glacial -interglacial cyclicity was identified based on the biogenic component and sedimentary structures observed in X-radiographs, magnetic susceptibility and lithofacies descriptions. Glacial intervals are dominated by fine-grained laminated mud and interglacial units consist of bioturbated muds enriched in biogenic components. From 2.2 to 0.76 Ma, planktonic foraminifera and calcareous nannofossils dominate in the interglacials suggesting a shift of the Antarctic Polar Front (APF) to the south near the drifts. Prior to 2.2 Ma, cyclicity cannot be identified and diatoms dominate the biogenic component and high percent opal suggests warmer conditions south of the APF and reduced sea ice over the drifts. Analyses of the coarse-grained terrigenous fraction (pebbles and coarse sand) from Sites 1096 and 1101 record glaciers at sea-level releasing iceberg-rafted debris (IRD) throughout the last 3.1 m.y. Analyses of quartz sand grains in IRD with the scanning electron microscope (SEM) show an abrupt change in the frequency of occurrence of microtextures at similar to 1.35 Ma. During the Late Pliocene to Early Pleistocene, the population of quartz grains included completely weathered grains and a low frequency of crushing and abrasion, suggesting that glaciers were small and did not inundate the topography. Debris shed from mountain peaks was transported supraglacially or englacially allowing weathered grains to pass through the glacier unmodified. During glacial periods from 1.35-0.76 Ma, glaciers expanded in size. The HID flux was very high and dropstones have diverse lithologies. Conditions resembling those at the Last Glacial Maximum (LGM) have been episodically present on the Antarctic Peninsula since similar to 0.76 Ma. Quartz sand grains show high relief, fracture and abrasion common under thick ice and the IRD flux is low with a more restricted range of dropstone lithologies.
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are antarctic peninsula ice sheet grounding events manifest in sedimentary cycles on the adjacent Continental Rise
Marine Geology, 2007Co-Authors: Philip J Bart, Clausdieter Hillenbrand, Werner Ehrmann, Masao Iwai, D Winter, Sophie WarnyAbstract:The direct record of Late Miocene–Early Pliocene Antarctic Peninsula Ice Sheet expansions from a previously published seismostratigraphic study of the outer shelf at Ocean Drilling Program Site 1097 is compared to the glacial history we deduced from published proxy evidence within coeval sections on the adjacent Continental Rise. The proxies are sedimentary structures (laminated vs. massive/bioturbated facies) and clay minerals (predominantly smectite and chlorite contents) from Ocean Drilling Program Site 1095 located on the distal part of a large drift. The comparison shows that more sedimentary cycles are evident on the Continental Rise for three of the four diatom biozones we considered. This indicates that the Continental-Rise sedimentology may indeed be related to local or regional paleoenvironmental variability, including Antarctic Peninsula Ice Sheet grounding events on the adjacent outer Continental shelf. If correct, this would be a promising result because unlike the outer Continental shelf sequences drilled thus far, the Continental Rise record is relatively continuous and can be dated using paleomagnetic and biostratigraphic data. However, our study also shows that no objective criteria provide direct linkages between the glacial history we deduced from the two Continental Rise proxies and that previously derived from the Continental-shelf seismic stratigraphy. Furthermore, the two sedimentologic proxies on the Continental Rise do not always provide a consistent picture of glacial history when compared against each other.
Carol J. Pudsey - One of the best experts on this subject based on the ideXlab platform.
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Processes on sediment drifts from 3.5 kHz data, Antarctic Peninsula Continental Rise
2020Co-Authors: Carol J. Pudsey, John A. Howe, Peter Morris, David E. GunnAbstract:On the Continental Rise west of the Antarctic Peninsula, large sediment drifts preserve a hihg-resolution record of Neogene glaciation, We present a new map of acoustic facies on the Continental Rise, derived from 3.5 kHz profiles. Most drifts have steep sides to the southeast (towards the base of the slope) and southwest (towards the channels which separate each drift). The gentle slopes of the drifts (to northeast, and merging with the abyssal plain to the northwest) contain laterally continuous sub-bottom reflectors. Convergence of reflectors to the northwest shows the sediments thin offshore, confirmed by core studies; strike lines show negligible thickness change acress the drifts, except within a few kilometres of the channels. It is likely that deposition from meltwater plumes and slope-derived turbidity currents pevailed over deposition from channelised turbidity currents. Small areas of sediment waves occur on two drifts. Evidence for small-scale mass wasting includes normal faults and slump blocks on the steep sides of all the the drifts, and one drift contains a number of small, locally derived debris flows. Both 3.5 kHz profiles and cores show evidence for a change in sedimentation style at c. 3300 m water depth, with intermittent bottom-current winnowing above this depth. Sedimentation rates from ODP Leg 178 show the acoustic penetration depth of some 50 m represents the last 0.5-1.0 m.y. of deposition.
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Data report: Dinoflagellate cyst analysis of Neogene sediments from Sites 1095 and 1096, Antarctic Peninsula Continental Rise
2020Co-Authors: Carol J. Pudsey, Rex HarlandAbstract:Protoperidiniacean dinoflagellate cysts were identified in 19 of 28 samples from two sites on the Antarctic Peninsula Continental Rise. Cysts are most common in the lower Pliocene and upper Miocene and include species of Brigantedinium, Lejeunecysta, and Selenopemphix. Autotrophic gonyaulacacean dinoflagellate cysts are very rare in the samples. The dominance of taxa derived from assumed heterotrophic dinoflagellate motile forms may indicate high nutrient content in the surface waters, which sustained a considerable diatom population.
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Data report: Grain-size data, Sites 1095, 1096, and 1101, Antarctic Peninsula Continental Rise
2020Co-Authors: Carol J. PudseyAbstract:Sites 1095, 1096, and 1101 were drilled on the Continental Rise west of the Antarctic Peninsula (Fig. F1) to recover a continuous high-resolution record of Antarctic glaciation. Site 1095 is the subject of a short paper in this volume (Pudsey, Chap. 25, this volume), whereas mass accumulation rates at the three sites are described by Wolf-Welling (Chap. 15, this volume) and ice-rafted debris at Site 1101 is discussed by Cowan (Chap. 10, this volume) This report documents grain-size data (sand and fine fraction) and the proportion of biogenic silica for the upper 300 m at Site 1095, the upper 250 m at Site 1096, and the whole 220 m at Site 1101.
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neogene record of antarctic peninsula glaciation in Continental Rise sediments odp leg 178 site 1095
2002Co-Authors: Carol J. PudseyAbstract:Site 1095 is the most distal of three Continental Rise sites drilled during Ocean Drilling Program Leg 178. A long (600 m), near-continuous section extends from the Holocene down to nearly 10-Ma sediments, comprising fine-grained turbidites, hemipelagites, and muddy contourites. Meter-scale lithologic cyclicity is seen in sediment facies, physical properties, composition, and grain size in the upper 300 m of the section, representing 0–7 Ma. The diatom content of the sediments suggests sea ice was a significant limitation on productivity only during the Pleistocene. Fine grain size implies that bottom currents were never significantly stronger that at present during the last 7 m.y. The presence of ice-rafted debris implies the Antarctic Peninsula was not deglaciated for any significant period during the “warm Pliocene” (3.2–4.5 Ma). Intermittent supply of fine terrigenous sediment to the Rise is consistent with published depositional models showing the ice sheet grounded to the shelf edge during glacial periods. At some times, particularly during the late Miocene, processes related to submarine channel switching and lobe progradation may have masked climatic control on deposition at this site.
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late quaternary iceberg rafting along the antarctic peninsula Continental Rise and in the weddell and scotia seas
Quaternary Research, 2001Co-Authors: Colm O Cofaigh, Julian A Dowdeswell, Carol J. PudseyAbstract:Abstract Sediment cores from the Continental Rise west of the Antarctic Peninsula and the northern Weddell and Scotia Seas were investigated for their ice-rafted debris (IRD) content by lithofacies logging and counting of particles >0.2 cm from core x-radiographs. The objective of the study was to determine if there are iceberg-rafted units similar to the Heinrich layers of the North Atlantic that might record periodic, widespread catastrophic collapse of basins within the Antarctic Ice Sheet during the Quaternary. Cores from the Antarctic Peninsula margin contain prominent IRD-rich units, with maximum IRD concentrations in oxygen isotope stages 1, 5, and 7. However, the greater concentration of IRD in interglacial stages is the result of low sedimentation rates and current winnowing, rather than regional-scale episodes of increased iceberg rafting. This is also supported by markedly lower mass accumulation rates (MAR) during interglacial periods versus glacial periods. Furthermore, thinner IRD layers within isotope stages 2–4 and 6 cannot be correlated between individual cores along the margin. This implies that the ice sheet over the Antarctic Peninsula did not undergo widespread catastrophic collapse along its western margin during the late Quaternary (isotope stages 1–7). Sediment cores from the Weddell and Scotia Seas are characterized by low IRD concentrations throughout, and the IRD signal generally appears to be of limited regional significance with few strong peaks that can be correlated between cores. Tentatively, this argues against pervasive, rapid ice-sheet collapse around the Weddell embayment over the last few glacial cycles.
Angelo Camerlenghi - One of the best experts on this subject based on the ideXlab platform.
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Relationship between Continental Rise development and palaeo-ice sheet dynamics, Northern Antarctic Peninsula Pacific margin
Quaternary Science Reviews, 2020Co-Authors: David Amblas, Roger Urgeles, Miquel Canals, Antoni Calafat, Michele Rebesco, Angelo Camerlenghi, Ferran Estrada, Marc De Batist, John E. Hughes-clarkeAbstract:12 pages, 7 figuresAcquisition of swath bathymetry data west of the North Antarctic Peninsula (NAP), between 63°S and 66°S, and its integration with the predicted seafloor topography of Smith and Sandwell [Global seafloor topography from satellite altimetry and ship depth soundings. Science 277, 1956-1962.] reveal the links between the Continental Rise depositional systems and the NAP palaeo-ice sheet dynamics. The NAP Pacific margin consists of a wide Continental shelf dissected by several troughs, tens of kilometres wide and long. The Biscoe Trough, which has been almost entirely surveyed with multibeam sonar, shows spectacular fan-shaped streamlining sea-floor morphologies revealing the presence of ice streams during the Last Glacial Maximum. In the study area the Continental Rise compRises the six northernmost sediment mounds of the NAP Pacific margin and the canyon-channel systems between them. These giant sediment mounds have developed since the early Neogene by southwest flowing bottom currents, which have redistributed along the margin the fine-grained component of the turbiditic currents flowing down canyon-channel systems. The widespread evidence of shallow slope instability within the sediment mounds has been identified from both swath bathymetry and topographic parametric sonar seismic reflection profiles. Bathymetric data show that the heads of all the Rise canyon-channel systems coincide geographically with the mouths of the major glacial troughs on the Continental shelf edge. This suggests a close genetic link between these morphological features and allows considering a glacio-sedimentary model for the western NAP outer margin seascape development. This model considers the availability of depositional space on the Continental Rise as the limiting factor for mound development. The depositional space, in turn, is controlled by the spacing between glacial maxima shelf-edge reaching ice streams. This model takes into account both glacial and interglacial scenarios and gives new insights on evaluating the palaeoenvironmental record of the Continental Rise sediment mounds. © 2005 Elsevier Ltd. All rights reservedThis study was supported by the Spanish (COHIMAR project, ref. REN2000-0896/ANT), Italian and Belgian Antarctic programs, Fullbright Commission GEMARANT project and Generalitat de Catalunya Grant 2001SGR-00076 to excellence research groups. Support from the Spanish ‘‘Ministerio de Educación, Cultura y Deporte’’ (D.A.) and ‘‘Ministerio de Ciencia y Tecnologı´a’’ (R.U.) through FPU and ‘‘Ramon y Cajal’’ fellowships, respectively, is greatly acknowledgedPeer Reviewe
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the present and past bottom current flow regime around the sediment drifts on the Continental Rise west of the antarctic peninsula
Marine Geology, 2008Co-Authors: Clausdieter Hillenbrand, Michele Rebesco, Angelo Camerlenghi, Renata G Lucchi, F J Hernandezmolina, Ellen A. Cowan, Gabriele UenzelmannnebenAbstract:Throughout the last decade large sediment drifts located on the upper Continental Rise west of the Antarctic Peninsula were the target of oceanographic measurements, bathymetric mapping, seismic investigations, shallow sediment coring, and deep-sea drilling by Ocean Drilling Program (ODP) Leg 178. These studies concluded that for most of the late Neogene and Quaternary a generally SW-ward directed bottom current affected the deposition on the drifts. In particular during glacial periods, the deposition was additionally influenced by NW-ward directed transport of terrigenous detritus supplied by turbidity currents from the Antarctic Peninsula Continental slope. In a recent study, however, the palaeomagnetic signal of the drift sediments recovered at two ODP Leg 178 sites (1095 and 1101) was interpreted to provide spatial and directional information on the physical record of the NE-ward flowing Antarctic Circumpolar Current (ACC). Here we investigate the link between the clockwise flowing ACC and the generally SW-wards flowing near-bottom contour current. We show that at the ODP Leg 178 sites on the western Antarctic Peninsula Continental margin the ACC only affects the ocean circulation above ca. 1000 m water depth. Therefore, the signal of ACC flow might only be archived in the ice-rafted debris (IRD) content of the drift sediments. However, the IRD from the Leg 178 sites accounts for only a small proportion of the drift sediments and is dominantly of local origin. Past variability of bottom-water flow around the sediment drifts was reconstructed on the basis of seismic studies and clay mineralogical and grain-size analyses. These reconstructions provide useful information about both downstream direction and velocity changes of the bottom current and point to its SW-ward flow along the upper Rise during at least the last 9.4 Ma.
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relationship between Continental Rise development and palaeo ice sheet dynamics northern antarctic peninsula pacific margin
Quaternary Science Reviews, 2006Co-Authors: David Amblas, Roger Urgeles, Miquel Canals, Antoni Calafat, Michele Rebesco, Angelo Camerlenghi, Ferran Estrada, Marc De Batist, John E HughesclarkeAbstract:Abstract Acquisition of swath bathymetry data west of the North Antarctic Peninsula (NAP), between 63°S and 66°S, and its integration with the predicted seafloor topography of Smith and Sandwell [Global seafloor topography from satellite altimetry and ship depth soundings. Science 277, 1956–1962.] reveal the links between the Continental Rise depositional systems and the NAP palaeo-ice sheet dynamics. The NAP Pacific margin consists of a wide Continental shelf dissected by several troughs, tens of kilometres wide and long. The Biscoe Trough, which has been almost entirely surveyed with multibeam sonar, shows spectacular fan-shaped streamlining sea-floor morphologies revealing the presence of ice streams during the Last Glacial Maximum. In the study area the Continental Rise compRises the six northernmost sediment mounds of the NAP Pacific margin and the canyon-channel systems between them. These giant sediment mounds have developed since the early Neogene by southwest flowing bottom currents, which have redistributed along the margin the fine-grained component of the turbiditic currents flowing down canyon-channel systems. The widespread evidence of shallow slope instability within the sediment mounds has been identified from both swath bathymetry and topographic parametric sonar seismic reflection profiles. Bathymetric data show that the heads of all the Rise canyon-channel systems coincide geographically with the mouths of the major glacial troughs on the Continental shelf edge. This suggests a close genetic link between these morphological features and allows considering a glacio-sedimentary model for the western NAP outer margin seascape development. This model considers the availability of depositional space on the Continental Rise as the limiting factor for mound development. The depositional space, in turn, is controlled by the spacing between glacial maxima shelf-edge reaching ice streams. This model takes into account both glacial and interglacial scenarios and gives new insights on evaluating the palaeoenvironmental record of the Continental Rise sediment mounds.
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Sediment Drifts on the Continental Rise of the Antarctic Peninsula
Glaciated Continental Margins, 1997Co-Authors: Michele Rebesco, Angelo CamerlenghiAbstract:The sediment drifts of the Antarctic Peninsula Pacific margin (Fig. 1) are a systematic component of a distinctive, fully glacial pattern of sediment transport and deposition. Terrigenous sediment supply is provided during glacial maxima by grounded ice sheets transporting unsorted tills to the Continental shelf edge.
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Giant sediment drifts on the Continental Rise west of the Antarctic Peninsula
Geo-Marine Letters, 1996Co-Authors: Michele Rebesco, Angelo Camerlenghi, Robert D. Larter, Peter F. BarkerAbstract:Multichannel seismic reflection profiles from the Continental Rise west of the Antarctic Peninsula between 63° and 69°S show the growth of eight very large mound-shaped sedimentary bodies. MCS profiles and long-range side-scan sonar (GLORIA) images show the sea floor between mounds is traversed by channels originating in a dendritic pattern near the base of the Continental slope. The mounds are interpreted as sediment drifts, constructed mainly from the fine-grained components of turbidity currents originating on the Continental slope, entrained in a nepheloid layer within the ambient southwesterly bottom currents and redeposited downcurrent.
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relationship between Continental Rise development and palaeo ice sheet dynamics northern antarctic peninsula pacific margin
Quaternary Science Reviews, 2006Co-Authors: David Amblas, Roger Urgeles, Miquel Canals, Antoni Calafat, Michele Rebesco, Angelo Camerlenghi, Ferran Estrada, Marc De Batist, John E HughesclarkeAbstract:Abstract Acquisition of swath bathymetry data west of the North Antarctic Peninsula (NAP), between 63°S and 66°S, and its integration with the predicted seafloor topography of Smith and Sandwell [Global seafloor topography from satellite altimetry and ship depth soundings. Science 277, 1956–1962.] reveal the links between the Continental Rise depositional systems and the NAP palaeo-ice sheet dynamics. The NAP Pacific margin consists of a wide Continental shelf dissected by several troughs, tens of kilometres wide and long. The Biscoe Trough, which has been almost entirely surveyed with multibeam sonar, shows spectacular fan-shaped streamlining sea-floor morphologies revealing the presence of ice streams during the Last Glacial Maximum. In the study area the Continental Rise compRises the six northernmost sediment mounds of the NAP Pacific margin and the canyon-channel systems between them. These giant sediment mounds have developed since the early Neogene by southwest flowing bottom currents, which have redistributed along the margin the fine-grained component of the turbiditic currents flowing down canyon-channel systems. The widespread evidence of shallow slope instability within the sediment mounds has been identified from both swath bathymetry and topographic parametric sonar seismic reflection profiles. Bathymetric data show that the heads of all the Rise canyon-channel systems coincide geographically with the mouths of the major glacial troughs on the Continental shelf edge. This suggests a close genetic link between these morphological features and allows considering a glacio-sedimentary model for the western NAP outer margin seascape development. This model considers the availability of depositional space on the Continental Rise as the limiting factor for mound development. The depositional space, in turn, is controlled by the spacing between glacial maxima shelf-edge reaching ice streams. This model takes into account both glacial and interglacial scenarios and gives new insights on evaluating the palaeoenvironmental record of the Continental Rise sediment mounds.