Multi-proxy palaeoenvironmental reconstruction of the Skagerrak from the Lateglacial to Middle Holocene

This study uses a multiproxy approach including the first use of 187Os/188Os, %C37:4 biomarkers, carbonate content, sedimentological grain size, geochemical X-ray fluorescence and microfossil benthic foraminifera species combined with radiocarbon dating, measured on six cores from across the Skagerrak, in order to study the Lateglacial to Middle Holocene history of the area. A new chronostratigraphic framework is developed based on the appearance of specific benthic foraminifera species along with changes in carbonate/X-ray fluorescence and grain size data. This allowed the correlation of cores based on a series of radiocarbon dated tie points. Analysing the cores together reveals several events recorded in the Skagerrak including: (i) an increased freshwater input (bracketed between 13.3 and 11.3 cal. ka BP) signified by radiogenic 187Os/188Os values, high %C37:4 values and an increase in sand content; (ii) the Glomma drainage event, signified by a sudden appearance of Valvulineria as well as higher %C37:4; and (iii) the opening of the Danish Straits and English Channel leading to the development of modern-day conditions and circulation patterns in the Skagerrak, signified by the appearance of Hyalinea balthica and a fall in %C37:4. We use foraminifera, X-ray fluorescence and grain-size data alongside radiocarbon dating to provide a chronostratigraphic framework linking together cores from the Skagerrak. Using this and changes in sand content, Ca/K, biomarkers (%C37:4), osmium isotope values (187Os/188Os) and foraminifera, we show evidence of three events in the Skagerrak from the Lateglacial to Middle Holocene. These include a freshwater input, the Glomma River drainage and the opening of the Danish Straits and English Channel. image