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  • 1
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    Record of a tectonically-controlled regression captured by changes in carbonate skeletal associations on a structured island shelf (mid-Pleistocene, Rhodes, Greece) (2013)
    Elsevier
    In:  Sedimentary Geology, 283 . pp. 15-33.
    Details
    Publication Date: 2018-07-19
    Description: The Plio–Pleistocene warm-temperate carbonate deposits along the SE coast of Rhodes (Greece) formed on a highly structured island ‘shelf’ during a major transgression-regression cycle, which reached bathyal depth during maximal transgression. The complex palaeobathymetry exhibits many characteristics of submarine canyons, especially of so-called ‘blind’ or ‘headless’ canyons — a canyon type, which is especially common in the modern Mediterranean. This study presents the palaeoenvironmental evolution of one of these canyons, which is today represented by the Lardos valley, eastern central Rhodes. The studied section comprises the middle Pleistocene (900–300 ka) and describes a shallowing-upward trend from bathyal to circalitoral depth. Thin fossiliferous debris flow layers document turnovers and abundance changes in fauna and floral of hard-bottom communities, which developed on the adjacent basement slopes and highs. The comparison of the obtained results with other studies from the southeastern coast of Rhodes suggests a high degree of diachroneity of lithological boundaries of these Plio–Pleistocene deposits, which can be best explained by progressive infill of small depocentres located at different altitude levels. Hence, lithological changes are interpreted to be time-transgressive from distal (low altitude) to proximal (high altitude) during transgression while time-transgressive from proximal to distal during regression. Consequently, the best chronostratigraphic correlation horizon is the surface of maximal transgression. The most probable age for this surface could be estimated at 1.1 to 0.8 Ma, 0.2–0.5 Ma younger than previous estimates. Furthermore, the current lithostratigraphic schemes for the Plio–Pleistocene deposits of southeastern Rhodes are reviewed and revised. Highlights ► The studied outcrop documents the uplift of Rhodes during the middle Pleistocene. ► The Plio–Pleistocene stratigraphy of Rhodes is reviewed and revised. ► The studied sedimentary unit is interpreted as submarine canyon deposit. ► Diachroneity of canyon deposits is most likely due to different altitudes of small depocentres.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.sedgeo.2012.11.001
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 2
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    Sedimentation patterns on a cold-water coral mound off Mauritania (2014)
    Elsevier
    In:  Deep-Sea Research Part II-Topical Studies in Oceanography, 99 . pp. 307-315.
    Details
    Publication Date: 2015-09-24
    Description: Highlights: • Cold-water coral mound formation is mainly influenced by the baffling of fine grained material within a coral framework. • Mass wasting appears to be an important mound progradation process. • Even heavily reworked sediments contain valuable information on the original mound aggradation processes. Abstract: An unconformity-bound glacial sequence (135 cm thick) of a coral-bearing sediment core collected from the flank of a cold-water coral mound in the Banda Mound Province off Mauritania was analysed. In order to study the relation between coral framework growth and its filling by hemipelagic sediments, U-series dates obtained from the cold-water coral species Lophelia pertusa were compared to 14C dates of planktonic foraminifera of the surrounding matrix sediments. The coral ages, ranging from 45.1 to 32.3 ka BP, exhibit no clear depositional trend, while on the other hand the 14C dates of the matrix sediment provide ages within a much narrower time window of 〈3000 yrs (34.6–31.8 cal ka BP), corresponding to the latest phase of the coral growth period. In addition, high-resolution computer tomography data revealed a subdivision of the investigated sediment package into three distinct parts, defined by the portion and fragmentation of corals and associated macrofauna as well as in the density of the matrix sediments. Grain size spectra obtained on the matrix sediments show a homogeneous pattern throughout the core sediment package, with minor variations. These features are interpreted as indicators of redeposition. Based on the observed structures and the dating results, the sediments were interpreted as deposits of a mass wasting event, namely a debris flow. During this event, the sediment unit must have been entirely mixed; resulting in averaging of the foraminifera ages from the whole unit and giving randomly distributed coral ages. In this context, for the first time mass wasting is proposed to be a substantial process of mound progradation by exporting material from the mound top to the flanks. Hence, it may not only be an erosional feature but also widening the base of the mound, thus allowing further vertical mound growth.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.dsr2.2013.07.004
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 3
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    The sediment composition and predictive mapping of facies on the Propeller Mound - A cold-water coral mound (Porcupine Seabight, NE Atlantic) (2010)
    Elsevier
    In:  Continental Shelf Research, 30 (17). pp. 1814-1829.
    Details
    Publication Date: 2015-09-25
    Description: Here we provide a detailed qualitative and quantitative insight on recent sediment composition and facies distribution of a cold-water coral (CWC) mound using the example of the Propeller Mound on the Irish continental margin (Hovland Mound Province, Porcupine Seabight). Five facies types on Propeller Mound are defined: (1) living coral framework, (2) coral rubble, (3) dropstone, (4) hardground, representing the on-mound facies, and (5) hemipelagic sediment facies, which describes the off-mound area. This facies definition is based on already published video-data recorded by Remotely Operated Vehicle (ROV), photo-data of gravity cores, box cores, and dredges from sediment surfaces as well as on the composition of the sediment fraction coarser than 125 μm, which has been analyzed on five selected box cores. Sediment compositions of the living coral framework and coral rubble facies are rather similar. Both sediment types are mainly produced by corals (34 and 35 wt%, respectively), planktonic foraminifers (22 and 29 wt%, respectively), benthic foraminifers (both 7 wt%), and molluscs (21 and 10 wt%, respectively), whereas the living coral framework characteristically features additional brachiopods (6 wt%). Hardgrounds are well-lithified coral rudstones rich in coral fragments (〉30 surf%), foraminifers, echinoderms, and bivalves. The dropstone facies and the hemipelagic sediment typically carry high amounts of lithoclasts (36 and 53 wt%, respectively) and planktonic foraminifers (35 and 32 wt%, respectively); however, their faunal diversity is low compared with the coral-dominated facies (12 and 〈2 wt% coral fragments, 7 and 6 wt% benthic foraminifers, and 4 and 0 wt% balanids). Using the maximum likelihood algorithm within ArcGIS 9.2, spatial prediction maps of the previously described mound facies are calculated over Propeller Mound and are based on mound morphology parameters, ground-truthed with the sedimentary and faunal information from box cores, photographs, and video-data. This method is tested for the first time for CWC ecosystems and provides areal estimates of the predicted facies, as well as suggests further occurrences of living coral frameworks, coral rubble, and dropstones, which are not discovered in the area yet. Thus, sediment composition analysis combined with facies prediction mapping might provide a potential new tool to estimate living CWC occurrences and sediment/facies distributions on CWC mounds, which is an important prerequisite for budget calculations and definition of marine protected areas, and which will improve our understanding of CWC mound formation.
    Type: Article , PeerReviewed
    Format: text
    DOI: 10.1016/j.csr.2010.08.007
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 4
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    Review of the Central and South Atlantic Shelf and Deep-Sea Benthos: Science, Policy, and Management (2023)
    Taylor & Francis
    Details
    Publication Date: 2023-09-21
    Description: The Central and South Atlantic represents a vast ocean area and is home to a diverse range of ecosystems and species. Nevertheless, and similar to the rest of the global south, the area is comparatively understudied yet exposed to increasing levels of multisectoral pressures. To counteract this, the level of scientific exploration in the Central and South Atlantic has increased in recent years and will likely continue to do so within the context of the United Nations (UN) Decade of Ocean Science for Sustainable Development. Here, we compile the literature to investigate the distribution of previous scientific exploration of offshore (30 m+) ecosystems in the Central and South Atlantic, both within and beyond national jurisdiction, allowing us to synthesise overall patterns of biodiversity. Furthermore, through the lens of sustainable management, we have reviewed the existing anthropogenic activities and associated management measures relevant to the region. Through this exercise, we have identified key knowledge gaps and undersampled regions that represent priority areas for future research and commented on how these may be best incorporated into, or enhanced through, future management measures such as those in discussion at the UN Biodiversity Beyond National Jurisdiction negotiations. This review represents a comprehensive summary for scientists and managers alike looking to understand the key topographical, biological, and legislative features of the Central and South Atlantic.
    Type: Book chapter , PeerReviewed
    Format: text
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    OceanRep: Book chapter
  • 5
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    Deglacial upslope shift of NE Atlantic intermediate waters controlled slope erosion and cold-water coral mound formation (Porcupine Seabight, Irish margin) (2020)
    Elsevier
    Details
    Publication Date: 2023-02-08
    Description: Highlights • Holocene cold-water coral mound formation started non-synchronous in Belgica province. • Coral mounds and slope sediments record changes in intermediate water mass dynamics. • Increased turbulent bottom currents steered slope erosion and mound formation. • Internal waves at the ENAW-MOW boundary enhance energy supply and particle flux. • Transition zone between the ENAW-MOW shifted 250 m upslope during the last deglacial. Abstract Turbulent bottom currents significantly influence the formation of cold-water coral mounds and sedimentation processes on continental slopes. Combining records from coral mounds and adjacent slope sediments therefore provide an unprecedented palaeo-archive to understand past variations of intermediate water-mass dynamics. Here, we present coral ages from coral mounds of the Belgica province (Porcupine Seabight, NE Atlantic), which indicate a non-synchronous Holocene re-activation in mound formation suggested by a temporal offset of ∼2.7 kyr between the deep (start: ∼11.3 ka BP at 950 m depth) and shallow (start: ∼8.6 ka BP at 700 m depth) mounds. A similar depth-dependent pattern is revealed in the slope sediments close to these mounds that become progressively younger from 22.1 ka BP at 990 m to 12.2 ka BP at 740 m depth (based on core-top ages). We suggest that the observed changes are the consequence of enhanced bottom-water hydrodynamics, caused by internal waves associated to the re-invigoration of the Mediterranean Outflow Water (MOW) and the development of a transition zone (TZ) between the MOW and the overlying Eastern North Atlantic Water (ENAW), which established during the last deglacial. These highly energetic conditions induced erosion adjacent to the Belgica mounds and supported the re-initiation of mound formation by increasing food and sediment fluxes. The striking depth-dependent patterns are likely linked to a shift of the ENAW-MOW-TZ, moving the level of maximum energy ∼250 m upslope since the onset of the last deglaciation.
    Type: Article , PeerReviewed
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 6
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    Glacio-eustatic variations and Sapropel events as main controls on the Middle Pleistocene-Holocene evolution of the Cabliers Coral Mound Province (W Mediterranean) (2021)
    Elsevier
    Details
    Publication Date: 2024-02-07
    Description: Highlights • Atlantic and Mediterranean water-mass interface depth affected coral mound growth. • Sapropel derived events had a detrimental influence on coral mound development. • A shift in the reef-building dominating coral species occurred during the Holocene. • The southern mound has been subjected to less favourable environmental conditions. Abstract Cold-water coral mounds are key hot-spots of deep ocean biodiversity and also important archives of past climatic conditions. Nonetheless, the paleo-oceanographic setting in which coral mounds developed in the Mediterranean Sea during the last 500 ka still needs to be properly understood. This study describes the coral deposits and corresponding ages of two on-mound gravity cores acquired from opposite sectors of the newly discovered Cabliers Coral Mound Province (CMP, Alboran Sea, W Mediterranean). U–Th data revealed Pleistocene-aged corals covering mound formation periods from 〉389 to 9.3 ka BP and from 13.7 to 0.3 ka BP in the southern and northern mounds respectively. The coral-rich deposits of the cores were mainly dominated by Desmophyllum pertusum, although in some sections concurrent with the Middle Pleistocene and the Holocene, other corals such as Dendrophyllia cornigera and Madrepora oculata also appeared as dominating species. Coral mound formation stages generally occurred during deglacials and temperate interstadial (3.5–4.1 δ18O‰) periods, whereas during interglacials (〈3.5 δ18O‰) coral mound formation only occurred in the northern and shallower mound. We interpret this to indicate that the shoaling of the interface between Atlantic (AW) and Levantine Intermediate Waters (LIW) during interglacial periods prevented the corals in the southern CMP from acquiring sufficient food supply, thus causing periods of coral mound stagnation. Similarly, the interruption in LIW formation throughout sapropel events also coincides with coral mound stagnation phases. This suggests that sapropel-derived processes, which originated in the eastern Mediterranean, likely affected the entire Mediterranean basin and further supports the role of LIW as a conveyor belt facilitating cold-water coral growth in the Mediterranean Sea. Overall, we show that these coral mounds yield important insights into how local changes in oceanographic conditions can influence coral mound development.
    Type: Article , PeerReviewed
    Format: text
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    OceanRep: Article in a Scientific Journal - peer-reviewed
  • 7
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    The giant Mauritanian cold-water coral mound province : oxygen control on coral mound formation (2018)
    Elsevier
    Details
    Publication Date: 2022-05-25
    Description: © The Author(s), 2018. This article is distributed under the terms of the Creative Commons Attribution License. The definitive version was published in Quaternary Science Reviews 185 (2018): 135-152, doi:10.1016/j.quascirev.2018.02.012.
    Description: The largest coherent cold-water coral (CWC) mound province in the Atlantic Ocean exists along the Mauritanian margin, where up to 100 m high mounds extend over a distance of ∼400 km, arranged in two slope-parallel chains in 400–550 m water depth. Additionally, CWCs are present in the numerous submarine canyons with isolated coral mounds being developed on some canyon flanks. Seventy-seven Uranium-series coral ages were assessed to elucidate the timing of CWC colonisation and coral mound development along the Mauritanian margin for the last ∼120,000 years. Our results show that CWCs were present on the mounds during the Last Interglacial, though in low numbers corresponding to coral mound aggradation rates of 16 cm kyr−1. Most prolific periods for CWC growth are identified for the last glacial and deglaciation, resulting in enhanced mound aggradation (〉1000 cm kyr−1), before mound formation stagnated along the entire margin with the onset of the Holocene. Until today, the Mauritanian mounds are in a dormant state with only scarce CWC growth. In the canyons, live CWCs are abundant since the Late Holocene at least. Thus, the canyons may serve as a refuge to CWCs potentially enabling the observed modest re-colonisation pulse on the mounds along the open slope. The timing and rate of the pre-Holocene coral mound aggradation, and the cessation of mound formation varied between the individual mounds, which was likely the consequence of vertical/lateral changes in water mass structure that placed the mounds near or out of oxygen-depleted waters, respectively.
    Description: This study received funding from and contributes to the DFG-projects "Palaeo-WACOM" (HE 3412/17-1) and "Cold-water coral mound development in a tropical upwelling cell – the great wall of(f) Mauritania" (Ti 706/3-1). A. Freiwald received funding from the Hessian initiative for the development of scientific and economic excellence (LOEWE) at the Biodiversity and Climate Research Centre (BiK-F), Frankfurt, Germany.
    Keywords: Lophelia pertusa ; Coral mound ; Submarine canyon ; Uranium-series dating ; Mound aggradation rate ; Last glacial ; Dissolved oxygen concentration ; South Atlantic Central Water ; Mauritanian margin
    Repository Name: Woods Hole Open Access Server
    Type: Article
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