Assessment of [delta] 13C and C/N ratios in bulk organic matter as palaeosalinity indicators in holocene and lateglacial isolation basin sediments, northwest Scotland

Carbon isotopes (13C) and C/N ratios from bulk organic matter have recently been used as alternative proxies for relative sea-level (RSL) reconstruction where there are problems associated with conventional biological indictors. A previous study on a single isolation basin (Upper Loch nan Eala) in northwest Scotland has shown a clear relationship between 13C, C/N ratios and palaeosalinity from Younger Dryas and Holocene aged sediments. In this paper we present results of 13C and C/N ratio analyses from other isolation basins in northwest Scotland over the Holocene and the Lateglacial period in order to validate this technique. The results from the Holocene sequences support the earlier findings that this technique can be used to identify RSL change from isolation basins over the Holocene in this region. The relationship between 13C, C/N ratios and RSL change is not apparent in sediments of Lateglacial age. Other environmental variables such as atmospheric CO2 concentration, poor vegetation development and temperature influence 13C values during this period.