Late glacial sedimentology, foraminifera and stable isotope stratigraphy of the Hebridean Continental Shelf, northwest Scotland

Abstract

Abstract The detailed stratigraphies of two shallow marine cores from the Hebridean shelf of northwest Scotland are presented. The results provide evidence on the timing of deglaciation from about 15.2 ka BP , with evidence of cold, low salinity water persisting on the shelf until at least 13.5 ka BP . After 13.5 ka BP , probably shortly before 13.0 ka BP , warm shallow shelf seas were established and persisted throughout much of the interstadial. There is some evidence for climatic instability during the interstadial and for a cooling trend from after 11.6 ka BP . Glacial isostatic rebound of the shelf seems to have kept pace with eustatic sea level rise until about 11 ka BP . The fully developed conditions of the Younger Dryas stadial are not observed until 11 ka BP . For the first time from the marine record the constituent tephra peaks of North Atlantic Ash Zone 1 are resolved into a sequence of eruptive events and demonstrate that extensive sea ice transgressed the western UK continental shelf throughout the Younger Dryas. The climatic conditions of the Younger Dryas persist until an initial, precursor warming at 10.2 ka BP , followed by a marked warming of about 8°C and fully established early Holocene temperatures before 10 ka BP . Many of the changes recorded through nearly 5 m of sediments accumulated during the Younger Dryas can be related to changing relative sea levels and source supply.