Open AccessDeglacial to postglacial palaeoenvironments of the C eltic S ea: lacustrine conditions versus a continuous marine sequence
Author(s) -
Furze Mark F. A.,
Scourse James D.,
Pieńkowski Anna J.,
Marret Fabienne,
Hobbs William O.,
Carter Rosemary A.,
Long Brian T.
Publication year - 2014
Publication title -
boreas
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.95
H-Index - 74
eISSN - 1502-3885
pISSN - 0300-9483
DOI - 10.1111/bor.12028
Subject(s) - geology , meltwater , paleontology , subaerial , oceanography , foraminifera , southern hemisphere , arctic , glacial period , climatology , benthic zone
Recent work on the last glaciation of the B ritish I sles has led to an improved understanding of the nature and timing of the retreat of the B ritish− I rish I ce Sheet ( BIIS ) from its southern maximum ( I sles of S cilly), northwards into the C eltic and I rish seas. However, the nature of the deglacial environments across the C eltic S ea shelf, the extent of subaerial exposure and the existence (or otherwise) of a contiguous terrestrial linkage between B ritain and I reland following ice retreat remains ambiguous. Multiproxy research, based on analysis of 12 BGS vibrocores from the C eltic D eep B asin ( CDB ), seeks to address these issues. CDB cores exhibit a shell‐rich upward fining sequence of H olocene marine sand above an erosional contact cut in laminated muds with infrequent lonestones. Molluscs, in situ Foraminifera and marine diatoms are absent from the basal muds, but rare damaged freshwater diatoms and foraminiferal linings occur. Dinoflagellate cysts and other non‐pollen palynomorphs evidence diverse, environmentally incompatible floras with temperate, boreal and A rctic glaciomarine taxa co‐occurring. Such multiproxy records can be interpreted as representing a retreating ice margin, with reworking of marine sediments into a lacustrine basin. Equally, the same record may be interpreted as recording similar conditions within a semi‐enclosed marine embayment dominated by meltwater export and deposition of reworked microfossils. As assemblages from these cores contrast markedly with proven glaciomarine sequences from outside the CDB , a glaciolacustrine interpretation is favoured for the laminated sequence, truncated by a L ate W eichselian transgressive sequence fining upwards into fully marine conditions. Reworked rare intertidal molluscs from immediately above the regional unconformity provide a minimum date c. 13.9 cal. ka BP for commencement of widespread marine erosion. Although suggestive of glaciolacustrine conditions, the exact nature and timing of laminated sediment deposition within the CDB , and the implications this has on (pen)insularity of I reland following deglaciation, remain elusive.