Biomarkers as paleoclimate proxies in peatlands in coastal high plains in Asturias, N Spain

Abstract

This study represents an attempt to correlate wet and dry episodes as defined by biomarker parameters in peat profiles of Asturias (North Spain). The peats developed in a coastal location on high plains at heights ranging between 115 and 256m above sea level. The peat profiles which cover different Holocene intervals exhibit growth rates ranging from 0.05 to 0.56mm/yr and so provide records of different resolution.Biomarkers have revealed the widespread occurrence of nonadecan-2-one (K19), a characteristic of Cantabrian peatlands, different periods of dominance by higher plants and bacterial triterpenoids and an alternance of humid and dry periods as reflected in the n-alkane ratios. A change from a more arboreous vegetation before 4000cal.yr BP in the relatively dry warm climate of the Middle Holocene to a Sphagnum-herbaceous dominant vegetation typical of cooler wetter conditions is observed. The wet episode between 2200 and 3000cal.yr BP has a widespread occurrence in the studied profiles, whereas other dry–wet episodes are only recorded in some peat deposits and may be associated with local conditions.