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Low sea-level stand emplacement of megaturbidites in the western and eastern Mediterranean Sea

Low sea-level stand emplacement of megaturbidites in the western and eastern Mediterranean Sea
Low sea-level stand emplacement of megaturbidites in the western and eastern Mediterranean Sea
Piston cores from the Balearic and Herodotus Abyssal Plains in the Mediterranean Sea show that the Late Pleistocene to Holocene sedimentary sequence is dominated by turbidite muds. On each plain, one turbidite bed is conspicuous by its thickness, and this bed can be correlated basinwide on the basis of geochemical compositional analysis and its apparent correspondence with a distinct acoustically transparent layer on high-resolution seismic records. These megabeds on the two plains represent megaturbidites of very large volume (300–600 km3 each) and are shown by AMS radiocarbon dating to have been emplaced during the last low stand of sea-level at the height of the last glacial maximum. The megabed on the Balearic Abyssal Plain is derived from the southern European margin and is the main sedimentation event over the last 120 ka. It emplaced as much material as was deposited by smaller flows during the previous 25 ka. Sedimentation rate curves for the Balearic Abyssal Plain show that falling sea-level correlates with increased terrigenous deposition, and that gross sedimentation rates in the basin increased as sea level fell from 120–18 ka due to more frequent emplacement of distal turbidites. The Herodotus Abyssal Plain megabed is derived from the Libyan–Egyptian continental shelf west of the Nile Delta and was the dominant sedimentation event in this basin during the past 60 kyr. High-resolution seismic profiles from the Ionian and Sirte Abyssal Plains in the central Mediterranean also suggest possible low sea-level emplacement of megabeds in these regions. Available evidence suggests widespread emplacement of megaturbidites throughout the Mediterranean at the last glacial maximum. Although the triggering mechanisms for these events remain speculative, catastrophic destabilisation of the margin after a long period of accumulation with an increased rate of sediment supply is suggested.
MEGATURBIDITES, TURBIDITES, BALEARIC BASIN, HERODOTUS ABYSSAL PLAIN
0037-0738
75-88
Rothwell, R.G.
fe473057-bf44-46d1-8add-88060037beb5
Reeder, M.S.
0c391f66-bfab-4728-8412-403bcbfc5f07
Anastasakis, G.
4a0d8e38-6fc3-443d-8bb4-9fa676f2faae
Stow, D.A.V.
434350cd-0ae5-4bb3-b71f-e1da90587f74
Thomson, J.
3395054f-e507-4841-9758-a06ed37f7d6b
Kahler, G.
f5d3c308-797a-4817-b25c-48c6cb57b4b7
Rothwell, R.G.
fe473057-bf44-46d1-8add-88060037beb5
Reeder, M.S.
0c391f66-bfab-4728-8412-403bcbfc5f07
Anastasakis, G.
4a0d8e38-6fc3-443d-8bb4-9fa676f2faae
Stow, D.A.V.
434350cd-0ae5-4bb3-b71f-e1da90587f74
Thomson, J.
3395054f-e507-4841-9758-a06ed37f7d6b
Kahler, G.
f5d3c308-797a-4817-b25c-48c6cb57b4b7

Rothwell, R.G., Reeder, M.S., Anastasakis, G., Stow, D.A.V., Thomson, J. and Kahler, G. (2000) Low sea-level stand emplacement of megaturbidites in the western and eastern Mediterranean Sea. Sedimentary Geology, 135 (1/4), 75-88. (doi:10.1016/S0037-0738(00)00064-6).

Record type: Article

Abstract

Piston cores from the Balearic and Herodotus Abyssal Plains in the Mediterranean Sea show that the Late Pleistocene to Holocene sedimentary sequence is dominated by turbidite muds. On each plain, one turbidite bed is conspicuous by its thickness, and this bed can be correlated basinwide on the basis of geochemical compositional analysis and its apparent correspondence with a distinct acoustically transparent layer on high-resolution seismic records. These megabeds on the two plains represent megaturbidites of very large volume (300–600 km3 each) and are shown by AMS radiocarbon dating to have been emplaced during the last low stand of sea-level at the height of the last glacial maximum. The megabed on the Balearic Abyssal Plain is derived from the southern European margin and is the main sedimentation event over the last 120 ka. It emplaced as much material as was deposited by smaller flows during the previous 25 ka. Sedimentation rate curves for the Balearic Abyssal Plain show that falling sea-level correlates with increased terrigenous deposition, and that gross sedimentation rates in the basin increased as sea level fell from 120–18 ka due to more frequent emplacement of distal turbidites. The Herodotus Abyssal Plain megabed is derived from the Libyan–Egyptian continental shelf west of the Nile Delta and was the dominant sedimentation event in this basin during the past 60 kyr. High-resolution seismic profiles from the Ionian and Sirte Abyssal Plains in the central Mediterranean also suggest possible low sea-level emplacement of megabeds in these regions. Available evidence suggests widespread emplacement of megaturbidites throughout the Mediterranean at the last glacial maximum. Although the triggering mechanisms for these events remain speculative, catastrophic destabilisation of the margin after a long period of accumulation with an increased rate of sediment supply is suggested.

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More information

Published date: 2000
Keywords: MEGATURBIDITES, TURBIDITES, BALEARIC BASIN, HERODOTUS ABYSSAL PLAIN

Identifiers

Local EPrints ID: 8836
URI: https://eprints.soton.ac.uk/id/eprint/8836
ISSN: 0037-0738
PURE UUID: 3c439df5-ac9d-43e2-a179-e622dcad97b6

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Date deposited: 13 Sep 2004
Last modified: 17 Jul 2017 17:12

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