Outer shelf seafloor geomorphology along a carbonate escarpment: The eastern Malta Plateau, Mediterranean Sea

Submarine carbonate escarpments, documented in numerous sites around the world, consist of thick exposures of Mesozoic shallow water carbonate sequences – primarily limestones and dolomites – with reliefs of >1km and slope gradients of >70°. Whilst most research efforts have focused on the pro...

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Bibliographic Details
Published in:Continental shelf research 2016-12, Vol.131, p.12-27
Main Authors: Micallef, Aaron, Georgiopoulou, Aggeliki, Mountjoy, Joshu, Huvenne, Veerle A.I., Iacono, Claudio Lo, Le Bas, Timothy, Del Carlo, Paola, Otero, Daniel Cunarro
Format: Article
Language:English
Subjects:
Carbonate escarpment
Carbonates
Cenozoic Era
Channels
Contouritic drift
Erosion
Erosion mechanisms
Escarpments
Fault
Malta
Malta Plateau
Marine
Outer shelf
Shelves
Submarine landslide
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Summary:Submarine carbonate escarpments, documented in numerous sites around the world, consist of thick exposures of Mesozoic shallow water carbonate sequences – primarily limestones and dolomites – with reliefs of >1km and slope gradients of >70°. Whilst most research efforts have focused on the processes that shaped carbonate escarpments into complex and extreme terrains, little attention has been paid to the geomorphology of shelves upslope of carbonate escarpments. In this study we investigate high resolution geophysical, sedimentological and visual data acquired from the eastern Malta Plateau, central Mediterranean Sea, to demonstrate that the outer shelf of a carbonate escarpment is directly influenced by escarpment-forming processes. We document forty eight erosional scars, six long channels and numerous smaller-scale channels, three elongate mounds, and an elongate ridge across the eastern Malta Plateau. By analysing their morphology, seismic character, and sedimentological properties, we infer that the seafloor of the eastern Malta Plateau has been modified by three key processes: (i) Mass movements – in the form of translational slides, spreading and debris flows – that mobilised stratified Plio-Pleistocene hemipelagic mud along the shelf break and that were likely triggered by seismicity and loss of support due to canyon erosion across the upper Malta Escarpment; (ii) NNW-SSE trending sinistral strike-slip deformation in Cenozoic carbonates – resulting from the development of a mega-hinge fault system along the Malta Escarpment since the Late Mesozoic, and SE-NW directed horizontal shortening since the Late Miocene – which gave rise to NW-SE oriented extensional grabens and a NNW-SSE horst; (iii) Flow of bottom currents perpendicular and parallel to the Malta Escarpment, associated with either Modified Atlantic Water flows during sea level lowstands and/or Levantine Intermediate Water flows at present, which was responsible for sediment erosion and deposition in the form of channels and contouritic drifts. •We investigate geomorphic processes in the outer shelf of a carbonate escarpment.•Study is based on geophysical, sedimentological and visual data from Malta Plateau.•Erosional scars, channels, elongate mounds, and an elongate ridge are documented.•Key processes are slope instability, strike-slip deformation, bottom current flow.•Outer shelf geomorphology is directly influenced by escarpment-forming processes.
ISSN:0278-4343
1873-6955
DOI:10.1016/j.csr.2016.11.002