Organic matter accumulation and preservation in aquatic systems can be linked to variations in organic matter sources as well as primary productivity. These changes can be used to determine contemporaneous environmental variations in the catchment area. The source, quality and distribution of lacustrine organic matter (LOM) have been determined in a sedimentary core covering the last ~1,500 years from Laguna Mar Chiquita, a saline lake in central Argentina. Petrophysical, sedimentological and geochemical data along with results of high-resolution pigment analyses provide a unique dataset that allow characterization of both source and type of LOM. Climatically triggered changes in the Laguna Mar Chiquita catchment led to changes in the water salinity and lake trophic state that in turn influenced primary productivity and thus organic matter accumulation. Distinctive high lake water levels and associated low salinity characterize the Medieval Climatic Anomaly (MCA) as well as the last quarter of the twentieth century and beginning of the twentyfirst century. Conversely, extremely low lake levels with resulting high salinity correspond with the Little Ice Age (LIA). High-resolution sedimentary pigment analyses in these two end–members (i.e., LIA and MCA) do not indicate major changes in the structure of phototrophic communities signifying that the biota survives a large range of salinity and temperature. High lake stands (low salinity) correspond with increased primary productivity as shown by high pigment concentrations along with a decrease in authigenic carbonates and evaporites. These high lake level intervals have been previously linked to a warmer and more humid climate. Conversely, low lake levels (hyper saline waters) correlate with decreasing lake productivity and precipitation of both authigenic carbonates and evaporites. These sediments correspond to cooler intervals with a negative moisture balance. The relative similarity between LOM indicated by the pigment stratigraphy for both intervals show no clear evidence of a linkage between human impact and lake productivity. Hence, Laguna Mar Chiquita has been naturally productive even prior to agriculture expansion by the end of the twentieth century.
|Number of pages||18|
|Journal||Journal of Paleolimnology|
|State||Published - Feb 2014|
Bibliographical noteFunding Information:
This research has profited from the invaluable help from the scientific staff of both the Istituto per lo Studio degli Ecosistemi (Verbania-Pallanza, Italy) and the CICTERRA (Universidad de Córdoba/CONICET, Argentina). A. Gilli from the Limnogeology Laboratory at the ETH-Zurich, Switzerland, is gratefully thanked for helping with petrophysical measurements and useful discussions. We also thank T. Adatte from the University of Lausanne, Switzerland, for Rock–Eval analyses. This work was partially funded by CONICET (PIP-11220110100759), SECYT-UNC (2012–2013), PID-2008 (Ministerio de Ciencia y Tecnología de la Provincia de Córdoba), European Community’s Seventh Framework Programme (FP7/2007–2013) under Grant Agreement No 212492: CLARIS LPB, “A Europe-South America Network for Climate Change Assessment and Impact Studies in La Plata Basin”. The authors kindly acknowledge the thoughtful comments of two anonymous reviewers as well as Associated Editor S. Metcalfe and Chief Editor T. J. Whitmore.
© 2014, Springer Science+Business Media Dordrecht.
- Central Argentina
- Fossil pigments
- Organic matter
- Saline lake
- Subtropical South America
ASJC Scopus subject areas
- Aquatic Science
- Earth-Surface Processes