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  • 1
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    Response of Cenozoic turbidite system to tectonic activity and sea-level change off the Zambezi Delta. (2017)
    SPRINGER
    In:  EPIC3Marine Geophysical Research, SPRINGER, 38(3), pp. 209-226, ISSN: 0025-3235
    Details
    Publication Date: 2017-09-10
    Description: Submarine fans and turbidite systems are important and sensitive features located offshore from river deltas that archive tectonic events, regional climate, sea level variations and erosional process. Very little is known about the sedimentary structure of the 1800 km long and 400 km wide Mozambique Fan, which is fed by the Zambezi and spreads out into the Mozambique Channel. New multichannel seismic profiles in the Mozambique Basin reveal multiple feeder systems of the upper fan that have been active concurrently or consecutively since Late Cretaceous. We identify two buried, ancient turbidite systems off Mozambique in addition to the previously known Zambezi-Channel system and another hypothesized active system. The oldest part of the upper fan, located north of the present-day mouth of the Zambezi, was active from Late Cretaceous to Eocene times. Regional uplift caused an increased sediment flux that continued until Eocene times, allowing the fan to migrate southwards under the influence of bottom currents. Following the mid-Oligocene marine regression, the Beira High Channel-levee complex fed the Mozambique Fan from the southwest until Miocene times, reworking sediments from the shelf and continental slope into the distal abyssal fan. Since the Miocene, sediments have bypassed the shelf and upper fan region through the Zambezi Valley system directly into the Zambezi Channel. The morphology of the turbidite system off Mozambique is strongly linked to onshore tectonic events and the variations in sea level and sediment flux.
    Repository Name: EPIC Alfred Wegener Institut
    Type: Article , isiRev
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  • 2
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    Sedimentation and potential venting on the rifted continental margin of Dronning Maud Land (2016)
    SPRINGER
    In:  EPIC3Marine Geophysical Researches, SPRINGER, 37(4), pp. 313-324, ISSN: 0025-3235
    Details
    Publication Date: 2017-01-13
    Description: The relief of Dronning Maud Land (DML), formed by Middle and Late Mesozoic tectonic activity, had a strong spatial control on the early fluvial and subsequent glacial erosion and deposition. The sources, processes, and products of sedimentation along the DML margin and in the Lazarev Sea in front of the DML Mountains have been barely studied. The onshore mountain belt parallel to the coast of the DML margin acts as a barrier to the transport of terrigenous sediments from the east Antarctic interior to the margin and into the Lazarev Sea. Only the Jutul-Penck Graben system allows a localized ice stream controlled transport of material from the interior of DML across its old mountain belt. Offshore, we attribute repeated large-scale debris flow deposits to instability of sediments deposited locally on the steep gradient of the DML margin by high sediment flux. Two types of canyons are defined based on their axial dimensions and originated from turbidity currents and slope failures during glacial/fluvial transport. For the first time, we report pipe-like seismic structures in this region and suggest that they occurred as consequences of volcanic processes. Sedimentary processes on the Dronning Maud Land margin were studied using seismic reflection data and we restricted the seismic interpretation to the identification of major seismic sequences and their basal unconformities.
    Repository Name: EPIC Alfred Wegener Institut
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  • 3
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    A new pathway for Deep water exchange between the Natal Valley and Mozambique Basin? (2014)
    SPRINGER
    In:  EPIC3Geo-Marine Letters, SPRINGER, 34(6), pp. 525-540, ISSN: 0276-0460
    Details
    Publication Date: 2014-11-17
    Description: Although global thermohaline circulation pathways are fairly well known, the same cannot be said for local circulation pathways. Within the southwest Indian Ocean specifically there is little consensus regarding the finer point of thermohaline circulation. We present recently collected multibeam bathymetry and PARASOUND data from the northern Natal Valley and Mozambique Ridge, southwest Indian Ocean. These data show the Ariel Graben, a prominent feature in this region, creates a deep saddle across the Mozambique Ridge at ca. 28°S connecting the northern Natal Valley with the Mozambique Basin. Results show a west to east change in bathymetric and echo character across the northern flank of the Ariel Graben. Whereby eroded plastered sediment drifts in the west give way to aggrading plastered sediment drift in the midgraben, terminating in a field of seafloor undulations in the east. In contrast, the southern flank of the Ariel Graben exhibits an overall rugged character with sediments ponding in bathymetric depressions in between rugged sub/outcrop. It is postulated that this change in seafloor character is the manifestation of deep water flow through the Ariel Graben. Current flow stripping, due to increased curvature of the graben axis, results in preferential deposition of suspended load in an area of limited accommodation space consequently developing an over-steepened plastered drift. These deposited sediments overcome the necessary shear stresses, resulting in soft sediment deformation in the form of down-slope growth faulting (creep) and generation of undulating sea-floor morphology. Contrary to previous views, our works suggests that water flows from west to east across the Mozambique Ridge via the Ariel Graben.
    Repository Name: EPIC Alfred Wegener Institut
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  • 4
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    Seafloor morphology in the Mozambique Channel: Evidence for long-term persistent bottom-current flow and deep-reaching eddy activity (2017)
    SPRINGER
    In:  EPIC3Marine Geophysical Research, SPRINGER, 38(3), pp. 241-269, ISSN: 0025-3235
    Details
    Publication Date: 2017-09-10
    Description: The Mozambique Channel plays a key role in the exchange of surface water masses between the Indian and Atlantic Oceans and forms a topographic barrier for meridional deep and bottom water circulation due to its northward shoaling water depths. New high-resolution bathymetry and sub-bottom profiler data show that due to these topographic constraints a peculiar seafloor morphology has evolved, which exhibits a large variety of current- controlled bedforms. The most spectacular bedforms are giant erosional scours in the southwest, where northward spreading Antarctic Bottom Water is topographically blocked to the north and deflected to the east forming furrows, channels and steep sediment waves along its flow path. Farther north, in the water depth range of North Atlantic Deep Water, the seafloor is strongly shaped by deep-reaching eddies. Steep, upslope migrating sediment waves in the west have formed beneath the southward flow of anticyclonic Mozambique Channel eddies (MCEs). Arcuate bedforms in the middle evolved through an interaction of the northward flow of MCEs with crevasse splays from a breach in the western Zambezi Channel levee. Hummocky bedforms in the east result from an interplay of East Madagascar Current eddies with overspill deposits of the crevasse and Zambezi Channel. All bedforms are draped with sediments indicating that the present-day current velocities are not strong enough to erode sediments. Hence, it can be concluded that the seafloor morphology developed during earlier times, when bottom-current velocities were stronger. Assuming a sedimentation rate of 20 m/Ma and a drape of at least 50 m thickness the bedforms may have developed during the Pliocene Epoch or earlier.
    Repository Name: EPIC Alfred Wegener Institut
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  • 5
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    Paleo-bathymetry of the northern North Atlantic and consequences for the opening of the Fram Strait (2013)
    SPRINGER
    In:  EPIC3Marine Geophysical Researches, SPRINGER, 34(1), pp. 25-43, ISSN: 0025-3235
    Details
    Publication Date: 2017-10-20
    Description: In the past decade, the geophysical data base in the northern North Atlantic and central Arctic Ocean constantly grew. Though far from being complete, the information from new aeromagnetic and seismic data north of the Jan Mayen Fracture Zone and in the Arctic Ocean, in combination with existing compiled geological and geophysical data, is used to produce paleo-bathymetric maps for several Cenozoic time intervals. This paleo-bathymetric model provides evidence for an initial deep-water exchange through the Fram Strait starting around 17 Ma. Furthermore, the model suggests that crustal rifting prior to initial seafloor spreading might have facilitated an earlier deep-water connection. The paleobathymetric model indicates that the first possibility for a deep-water overflow from the Norwegian-Greenland Sea to the North Atlantic could have been between 15 Ma and 20 Ma. This confirms that the paleo-topography of the Yermak Plateau played an important role in allowing the exchange of shallow water between the northern North Atlantic and the Arctic Ocean before the opening of the deep-water Fram Strait gateway.
    Repository Name: EPIC Alfred Wegener Institut
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  • 6
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    Crustal variability along the rifted/sheared East African margin (2021)
    SPRINGER
    In:  EPIC3Geo-Marine Letters, SPRINGER, 41(2), pp. 19, ISSN: 0276-0460
    Details
    Publication Date: 2021-09-12
    Description: The East African margin between the Somali Basin in the north and the Natal Basin in the south formed as a result of the Jurassic/ Cretaceous dispersal of Gondwana. While the initial movements between East and West Gondwana left (oblique) rifted margins behind, the subsequent southward drift of East Gondwana from 157 Ma onwards created a major shear zone, the Davie Fracture Zone (DFZ), along East Africa. To document the structural variability of the DFZ, several deep seismic lines were acquired off northern Mozambique. The profiles clearly indicate the structural changes along the shear zone from an elevated continental block in the south (14°–20°S) to non-elevated basement covered by up to 6-km-thick sediments in the north (9°–13°S). Here, we compile the geological/geophysical knowledge of five profiles along East Africa and interpret them in the context of one of the latest kinematic reconstructions. A pre-rift position of the detached continental sliver of the Davie Ridge between Tanzania/ Kenya and southeastern Madagascar fits to this kinematic reconstruction without general changes of the rotation poles
    Repository Name: EPIC Alfred Wegener Institut
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