'The Scientific and Technological Research Council of Turkey'
Doi
Abstract
This work aims to study recent climatic oscillations and their influence on sedimentation in the Ria de Vigo, a
coastal embayment in Galicia, NW Spain. It is based on the study of clay mineral assemblages, in conjunction with other
proxies (granulometric, geochemical, geochronological and microfaunal), in the core KSGX 24. A Benthic Foraminifera
High Productivity (BFHP) proxy was used to determine changes in the flux of organic matter (OM) at the bottom of
the study area. Total organic carbon (TOC) content is not a suitable proxy to estimate changes in the past supply of OM
due to diagenetic processes.The sedimentation was finest in 3 sections: ~ 230–214 cm, ~ 185–73 cm and ~ 20–0 cm. These muddy sections are
characterised, in general, by higher proportions of detrital minerals, concentrations of several chemical elements related
to lithogenic sources and BFHP values. In addition, these sections are impoverished in carbonates, Ca, Sr and La when
compared with the layers with the highest sand content.The clay mineral assemblage of the studied site, characterised by the dominance of illite, intermediate concentrations
of kaolinite and minor amounts of smectite and chlorite, reveals the prevalence of a typical temperate humid climate in
the last 3 ka BP, the estimated age for the core base. However, the quantities of illite and chlorite increase in the muddy
layers. The characteristics of these muddy layers were interpreted as representing relatively cold climatic oscillations
associated with the strengthening of northerly winds and the prevalence of an upwelling regime corresponding to wellknown
periods, such as the first cold period of the Upper Holocene (~ 2.9 ka cal BP), the Dark Ages (between ~ 2.2 - 1.2
ka cal BP) and the Little Ice Age (~ 0.6 ka cal BP)