Using linear discriminant analysis (LDA) of bulk lake sediment geochemical data to reconstruct lateglacial climate changes in the South Carpathian Mountains
  • Metaadatok
Tartalom: http://dx.doi.org/10.1016/j.quaint.2012.03.025
Archívum: MTA Könyvtár
Gyűjtemény: Status = Published


Type = Article
Cím:
Using linear discriminant analysis (LDA) of bulk lake sediment geochemical data to reconstruct lateglacial climate changes in the South Carpathian Mountains
Létrehozó:
Braun, M.
Hubay, K.
Magyari, E.
Veres, D.
Papp, I.
Bálint, M.
Dátum:
2013-04-19
Téma:
QA74 Analysis / analízis
QE02 Geochemistry / geokémia
Tartalmi leírás:
A multi-proxy approach is widely used for reconstructing climatic change in alpine lake sediments. This
study applied bulk sediment geochemistry to reconstruct lateglacial and early Holocene climatic change
in a glacial lake (Lake Brazi, 1740 m a.s.l.) in the Retezat Mts. (South Carpathians, Romania). The
lowermost 1 m part of a 4.9-m long sediment core, covering the period between 9950 and 15,750 cal BP,
was used for high resolution bulk analysis of major elements (Al2O3, SiO2, TiO2, CaO, MgO, K2O, Na2O,
Fe2O3, MnO, SO3). Linear discriminant analysis (LDA) was used to compare a priori classified main
chemical groups. Subsamples from the core were priory ordered to ?warm? and ?cold? groups respectively,
according to their age and evidence of cold and warm events in the record, as suggested by proxy
correlation with the lateglacial event stratigraphy of North Greenland Ice Core Project (NGRIP). The
discriminant function was calculated using concentrations of Al2O3, TiO2, CaO, MgO, K2O, Na2O, Fe2O3,
and MnO after log ratio transformation. Loss-on-ignition, silicon and sulphur concentrations were not
used for the discriminant analysis, but regarded as comparison proxies for checking up the validity of
outputs. Sediments deposited during ?cold? and ?warm? events were separated significantly by the LDA
function; 85.1% of the originally grouped cases were correctly classified under the LDA analysis. The
calculated discriminant scores indicated four ?cold? and four ?warm? events. Sediments ordered into the
?warm? group contained larger amounts of organic matter and sulphur, while sediment samples of the
?cold? group were characterized by the overall predominance of major oxides bound into inorganic
silicates. The discriminant scores showed strong correlation with the NGRIP d18O data (r ź 0.8135) and
with the pollen percentage sum of trees and shrubs (r ź 0.9460). Loss-on-ignition showed a somehow
weaker, but still conclusive linear relationship with the discriminant scores (r ź 0.7505). Discriminant
analyses of bulk sediment major oxide chemical data may be a useful tool to identify the impact of
climatic events upon the nature and composition of materials delivered to a lake basin.
Típus:
Article
PeerReviewed
Formátum:
text
Azonosító:
Braun, M. and Hubay, K. and Magyari, E. and Veres, D. and Papp, I. and Bálint, M. (2013) Using linear discriminant analysis (LDA) of bulk lake sediment geochemical data to reconstruct lateglacial climate changes in the South Carpathian Mountains. Quaternary International, 293. pp. 114-122. ISSN 10406182
Kapcsolat: