A stratigraphic investigation of the Celtic Sea megaridges based on seismic and core data from the Irish-UK sectors

QUATERNARY SCIENCE REVIEWS

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Article

Lockhart, Edward A.¹  Scourse, James D.²  Praeg, Daniel^3,4,10  Van Landeghem, Katrien J. J.¹  Mellett, Claire⁵  Saher, Margot¹  Callard, Louise⁶  Chiverrell, Richard C.⁷  Benetti, Sara⁸  Cofaigh, Colm O.⁶  Clark, Chris D.⁹ 

[1] Bangor Univ, Sch Ocean Sci, Menai Bridge LL59 5AB, Anglesey, Wales

[2] Univ Exeter, Coll Life & Environm Sci, Penryn TR10 9EZ, Cornwall, England

[3] OGS Ist Nazl Oceanog & Geofis Sperimentale, Trieste, Italy

[4] CNRS, Geoazur UMR 7329, Rue Albert Einstein, F-06560 Valbonne, France

[5] Wessex Archaeol, Portway House,Old Sarum Pk, Salisbury SP4 6EB, Wilts, England

[6] Univ Durham, Dept Geog, South Rd, Durham DH1 3LE, England

[7] Univ Liverpool, Dept Geog & Planning, Liverpool L69 3BX, Merseyside, England

[8] Ulster Univ, Sch Geog & Environm Sci, Coleraine BT52 1SA, Londonderry, North Ireland

[9] Univ Sheffield, Dept Geog, Sheffield S10 2TN, S Yorkshire, England

[10] Univ Fed Fluminense, Lab Geol Marinha, Ave Gen Milton Tavares de Souza Sn, BR-24210346 Niteroi, RJ, Brazil

关键词: Holocene;    Late Pleistocene;    Western Europe;    Celtic sea;    Stratigraphy;    Glaciation;    Tidal sand ridges;    Irish sea ice stream;   

DOI  :  10.1016/j.quascirev.2018.08.029

来源: Elsevier

【 摘 要 】

The Celtic Sea contains the world's largest continental shelf sediment ridges. These megaridges were initially interpreted as tidal features formed during post-glacial marine transgression, but glacigenic sediments have been recovered from their flanks. We examine the stratigraphy of the megaridges using new decimetric-resolution geophysical data correlated to sediment cores to test hypothetical tidal vs glacial modes of formation. The megaridges comprise three main units, 1) a superficial fining-upward drape that extends across the shelf above an unconformity. Underlying this drape is 2), the Melville Formation (MFm) which comprises the upper bulk of the megaridges, sometimes displaying dipping internal acoustic reflections and consisting of medium to coarse sand and shell fragments; characteristics consistent with either a tidal or glacifluvial origin. The MFm unconformably overlies 3), the Upper Little Sole Formation (ULSFm), previously interpreted to be of late Pliocene to early Pleistocene age, but here shown to correlate to Late Pleistocene glacigenic sediments forming a precursor topography. The superficial drape is interpreted as a product of prolonged wave energy as tidal currents diminished during the final stages of post-glacial marine transgression. We argue that the stratigraphy constrains the age of the MFm to between 24.3 and 14 ka BP, based on published dates, coeval with deglaciation and a modelled period of megatidal conditions during post-glacial marine transgression. Stratigraphically and sedimentologically, the megaridges could represent preserved glacifluvial features, but we suggest that they comprise post-glacial tidal deposits (MFm) mantling a partially-eroded glacial topography (ULSFm). The observed stratigraphy suggests that ice extended to the continental shelf-edge. (C) 2018 The Authors. Published by Elsevier Ltd.

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