CALL FOR PROPOSALS:

ORGANIZERS

  • Harvey Thorleifson, Chair
    Minnesota Geological Survey
  • Carrie Jennings, Vice Chair
    Minnesota Geological Survey
  • David Bush, Technical Program Chair
    University of West Georgia
  • Jim Miller, Field Trip Chair
    University of Minnesota Duluth
  • Curtis M. Hudak, Sponsorship Chair
    Foth Infrastructure & Environment, LLC

 

Paper No. 1
Presentation Time: 8:15 AM

THE CARBONATE FACTORY IN KARSTIC ENVIRONMENTS: SOURCES AND PROCESSES IN QUATERNARY IBERIAN LAKES


VALERO-GARCES, Blas Lorenzo1, MORENO, Ana2, MATA, M. Pilar3, GIRALT, Santiago4, MORELLON MARTELES, Mario5, CORELLA, Pablo6, MARTIN PUERTAS, Celia7 and BARREIRO-LOSTRES, Fernando2, (1)Pyrenean Institute of Ecology, Spanish National Research Council, Avda Montañana 1005, apdo 13034, Zaragoza, 50080, Spain, (2)Pyrenean INSTITUTE of Ecology, SPANISH NATIONAL RESEARCH COUNCIL, Avda Montañana 1005, apdo 13034, Zaragoza, 50080, Spain, (3)Spanish Geological Survey, Calle La Calera, 1, Tres Cantos, Madrid, 28760, Spain, (4)Institute of Earth Sciences Jaume Almera, Spanish National Research Council, Lluis Sole i Sabaris s/n, Barcelona, 08028, Spain, (5)Department of Surface Waters, Eawag (Das Wasserforschungs-Institut des ETH-Bereichs), Überlandstrasse 133. P. O. Box 611, Dübendorf, 8600, Switzerland, (6)Dept Geology and Paleontology, University of Geneva, Rue des Maraîchers 13, Geneve, CH-1205, Switzerland, (7)Helmholtz-Zentrum Potsdam, Deutches GeoForschungZentrum, Telegrafenberg, Potsdam, 14473, Germany, blas@ipe.csic.es

Carbonates are a main component of Iberian Quaternary lake sediments. In this contribution we summarize the main processes controlling carbonate deposition in Iberian lakes located in Mesozoic and Tertiary carbonate-dominated regions and originated by diverse karstic processes during the Quaternary. The lakes, relatively small (2 ha to 107 ha) and shallow (11 to 46 m) provide outstanding examples of the large variability of sedimentary facies, depositional subenvironments and sources.

Clastic carbonate-deposition dominated in glaciated mountains (Enol Lake, northern Spain) during glacial times and it was greatly controlled by surface drainage and geomorphology,. Increased endogenic carbonate productivity occurred during Holocene warmer periods. Clastic carbonates are also dominant in some small karstic lakes (Taravilla Lake, Iberian Range) where Late Holocene sediment infill is composed of fining upward sequences deposited during flood events. In most lakes, endogenic carbonate production occur in two settings: i) littoral platforms dominated by Chara meadows and ii) epilimnetic zone. Continuous preservation of varves since Mid Holocene only occurs in the deepest lake (Montcortès Lake, up to 30 m) where calcite laminae textures (massive, fining upward and coarsening upward) reflect changes in the seasonality of calcite precipitation. However, varves have been formed and preserved in most of the lakes during short periods associated to increased water depth and more frequent anoxic conditions. Reworking of littoral carbonates is common during shallow lake stages.

Lakes with very active karstic processes, particularly subaqueous spring discharge, are prone to intense re-sedimentation processes. In Banyoles lake (NE Spain), increased spring discharge after intense rain periods are responsible for large remobilization and re-suspension of the sediments accumulated in the deepest areas, leading to the deposition of thick homogeinites.

The Quaternary Spanish lake record underlines the large variability of facies, carbonate sources and depositional subenvironments in lake sequences. A correct interpretation of carbonate sources and depositional history is key to use lake sequences as archives of past global changes.

Meeting Home page GSA Home Page