25,000 Years of Palaeoenvironmental Records from Eastern Pyrenees Valleys
•
0 j'aime•587 vues
Colloque Q10 AFEQ CNF-INQUA 2016 - Paléoclimats et environnements quaternaires, quoi de neuf sous le soleil ? Bordeaux, 16, 17 et 18 Février 2016
Recommandé
Recommandé
Contenu connexe
Tendances
Tendances (20)
En vedette
En vedette (15)
Similaire à 25,000 Years of Palaeoenvironmental Records from Eastern Pyrenees Valleys
Similaire à 25,000 Years of Palaeoenvironmental Records from Eastern Pyrenees Valleys (20)
Plus de Fundació Marcel Chevalier
Plus de Fundació Marcel Chevalier (20)
Dernier
Dernier (20)
25,000 Years of Palaeoenvironmental Records from Eastern Pyrenees Valleys
- 1. Glaciation in the Eastern Pyrenees between NGRIP/GRIP GS-9 and GS-2a stadials: 25,000 years of palaeoenvironmental record in the Valira Valleys (Principality of Andorra) Valentí Turu and Guy Jalut Marcel Chevalier Earth Science Foundation, Ed. sociocultural La Llacuna, AD500 Andorra la Vella, Principality of Andorra. Corresponding author (E-mail: igeofundacio@andorra.ad
- 2. AMS 14C dating and δ13C Total carbon (bulk) from • Pure colluvial • Colluvial-alluvial mixture • Supraglacial-colluvial m. • Subglacial till • Gl-Fl over bedrock δ13C from vegetation average and can be used as a proxy • No laminites has been dated (aquatic plants), only subaerial sediments except subglacial tills (mixture)
- 3. Glaciolacustrine geochemistry • 232 stratigraphical descriptions • Basin analysis using sequence stratigraphy (Turu et al., 2016). • Chronostratigraphic benchmark for paleoenvironmental studies • Online database • Depicting the paleolake alkalinity using 21 samples • Major elements (Al, Si, Ca, Ti, ..) • Proxys: Ca, Fe, Al, Ti • Al/Ti ratio as detrital proxy
- 4. La Massana paleolake TURU. V., CALVET, M., BORDONAU J., GUNNELL, Y., DELMAS M., VILAPLANA J.M. & JALUT, G. (2016) Did Pyrenean glaciers dance to the beat of global climatic events? Evidence from the Wurmian sequence stratigraphy of an ice-dammed palaeolake depocentre in Andorra; HUGHES P.D. & WOODWARD J.C. (eds) Quaternary Glaciation in the Mediterranean Mountains. Geological Society, London, SP 433. DOI: 10.1144/SP433.6
- 5. Stratigraphy Stratigraphy based on the study of proglacial deltas
- 6. Arinsal tributary stratigraphy Sequence Stratigraphy classification by identifying unconformity surfaces
- 7. Chronostratigraphy TILL ---> TILL ---> TILL ---> TILL ---> TILL ---> Glacier front unstability is recorded on the basin (subglacial till sedimentation)
- 8. δ13C data Rythmic trend & decreassing δ13C values in each one
- 9. Fast Fourier Transform Wave length of 6.1 and 4.0 Kyrs are depicted !13C Valira Nord FFT -8 -7 -6 -5 -4 -3 -2 -1 0 0 2 4 6 8 10 12 14 Ka Magnituddel'armonic -!13C
- 11. Aridity
- 12. Cold and moist
- 13. Moister
- 15. Conclusions • Five aridity cycles, one each 4 Ka (FFT) • Three Heinrich events, one each 6.1 Ka (FFT) • These climatic events may be independent but their interference produce abrupt climatic shiftings between 17 and 36 Ka (19,000 yrs) • For that reason He are barely recognizable
- 16. Thank you Where is the key?