Open AccessLate Holocene climatic oscillations traced by clay mineral assemblages and other palaeoceanographic proxies in Ria de Vigo (NW Spain)
Author(s) -
V. Martins,
Fernando Rocha,
Cristina Sequeira,
Paula Martins,
J. F. Santos,
João Alveirinho Dias,
O. Weber,
Jean-Marie Jouanneau,
Belén Rubio Armesto,
Daniel Rey,
Ana M. Bernabéu,
Eduardo Silva,
Lázaro Laut,
Rubens César Lopes Figueira
Publication year - 2013
Publication title -
turkish journal of earth sciences
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.356
H-Index - 43
eISSN - 1303-619X
pISSN - 1300-0985
DOI - 10.3906/yer-1112-12
Subject(s) - geology , illite , chlorite , diagenesis , foraminifera , clay minerals , benthic zone , geochemistry , total organic carbon , holocene , upwelling , terrigenous sediment , oceanography , sedimentary rock , paleontology , quartz , ecology , biology
This work aims to study recent climatic oscillations and their influence on sedimentation in the Ria de Vigo, acoastal embayment in Galicia, NW Spain. It is based on the study of clay mineral assemblages, in conjunction with otherproxies (granulometric, geochemical, geochronological and microfaunal), in the core KSGX 24. A Benthic ForaminiferaHigh Productivity (BFHP) proxy was used to determine changes in the flux of organic matter (OM) at the bottom ofthe study area. Total organic carbon (TOC) content is not a suitable proxy to estimate changes in the past supply of OMdue to diagenetic processes.The sedimentation was finest in 3 sections: ~ 230–214 cm, ~ 185–73 cm and ~ 20–0 cm. These muddy sections arecharacterised, in general, by higher proportions of detrital minerals, concentrations of several chemical elements relatedto lithogenic sources and BFHP values. In addition, these sections are impoverished in carbonates, Ca, Sr and La whencompared with the layers with the highest sand content.The clay mineral assemblage of the studied site, characterised by the dominance of illite, intermediate concentrationsof kaolinite and minor amounts of smectite and chlorite, reveals the prevalence of a typical temperate humid climate inthe last 3 ka BP, the estimated age for the core base. However, the quantities of illite and chlorite increase in the muddylayers. The characteristics of these muddy layers were interpreted as representing relatively cold climatic oscillationsassociated with the strengthening of northerly winds and the prevalence of an upwelling regime corresponding to wellknownperiods, such as the first cold period of the Upper Holocene (~ 2.9 ka cal BP), the Dark Ages (between ~ 2.2 - 1.2ka cal BP) and the Little Ice Age (~ 0.6 ka cal BP)