These varved sediments are 30,000 years old and show a nice structure. Diatoms form white layers. The distance between such white layers is one year. Darker layers occure in larger distances. The red color is from sand- and siltstone in the near of this location and is correlated with precipitation. With this terrific conditions one can use this varved sediments for a time series for precipitation for analysis the climate conditions 30,000 years ago. E.g. the darker layers could be a result by the El Niño impact.
The varved sediments were deposited after a large landslide 30,000 years ago (dark masses in first picture). This landslide dammed a river (Rio las Conchas) what resulted in a wide lake in the Santa Maria Basin. In this lake these sediments were formed (bright masses in first picture).
This is a research in the frame of the Sonderforschungsbereich 267 Deformation Processes in the Andes of the DFG.
MARWAN, N., Trauth, M.H., Vuille, M., Kurths, J.: Comparing modern and Pleistocene ENSO-like influences in NW Argentina using nonlinear time series analysis methods, In: Climate Dynamics, 21 (2003), 317-326
TRAUTH, M.H., M.R. Strecker: Formation of landslide-dammed lakes during a wet period between 40,000 and 25,000 yr B.P. in northwestern Argentina, In: Palaeogeography Palaeoclimatology Palaeoecology, 153 (1999), 277-287
MARWAN, N.: Diplomarbeit: Untersuchung der Klimavariabilität in NW Argentinien mit Hilfe der quantitativen Analyse von Recurrence Plots.- Institut für Theoretische Physik, TU Dresden, 1999
TRAUTH, M.H., R. A. Alonso, K. R. Haselton, R. L. Hermanns, M.R. Strecker: Climate change and mass movements in the NW Argentine Andes, In: Earth and Planetary Science Letters, 179 (2000), 243-256
Poster: El Niño impact on Lake Deposits in NW Argentina 30,000 Years Ago, April 2000