Mid- and late-Holocene limnogeology of Laguna del Negro Francisco,northern Chile,and its palaeoclimatic implications

Abstract

Lacustrine sediments from the high elevation, endorheic, saline lake Negro Francisco (27°28'S/69°14'W, 4125 m) provide a detailed mid- and late-Holocene environmental history of the Southern Chilean Altiplano. Mineralogy, chemical composition and sedimentary facies analyses of the deposits confirm the regional significance of mid-Holocene aridity between 6000 and 3800 BP. Precipitation rates were signifi cantly lower than the c. 250 mm yr^-1 of today. Fully arid conditions were interrupted by short-term moist spells with an average return period of about 200 years. Effective moisture increased after 3800 BP and peaked between 3000 and 2600 BP and between 2200 and 1800 BP in two phases with conditions more humid than today. Comparison with regional palaeodata suggest that these two late-Holocene humid spells were most likely related to Pacific moisture sources. Salinity levels increased again in Laguna del Negro Francisco after 1800 BP. The onset of modern climatic conditions was a stepwise, nonlinear process. However, the functioning of modern climate in this remote part of the world is not understood well enough to explain fully possible mech anisms of climatic changes in the past.

Keywords

Lake sediments mid-Holocene aridity saline lakes arid Andes climatic change precipitation rates facies analysis geochronology Chile.

Get full access to this article

View all access options for this article.

References

Blunier, T. , Chapellaz, J. , Schwander, J. , Stauffer, B. and Raynaud, D. 1995: Variations in atmospheric methane concentration during the Holocene epoch. Nature 374, 46-49.

Goldsmith, J.R. and Graf, D.L. 1958: Relation between lattice constants and composition of the Ca-Mg carbonates. American Mineralogist 43, 84-101.

Grosjean, M. and Nuñez, L.A. 1994: Lateglacial, early and middle Holocene environments, human occupation, and resource use in the Atacama (northern Chile). Geoarchaeology: An International Journal 9, 271-86.

Grosjean, M. , Geyh, M.A. , Messerli, B. and Schotterer, U. 1995a: Lateglacial and early Holocene lake sediments, groundwater formation and climate in the Atacama Altiplano 22-24°S. Journal of Paleolimnology 14, 2412-52.

Grosjean, M. , Messerli, B. , Ammann, C. , Geyh, M.A. , Graf, K. , Jenny, B. , Kammer, K. , Núñez, L. , Schotterer, U. , Schreier, H. , Schwalb, A. , Valero, B. and Vuille, M. 1995b: Holocene environmental changes in the Atacama Altiplano and paleoclimatic implications. Bulletin de l'Institut Français des Etudes Andines 24/3, 585-94.

Jenny, B. and Kammer, K. 1996: Jungquartäre Vergletscherungen auf dem Chilenischen Altiplano . Geographica Bernensia G46, 1-80.

Markgraf, V. 1989: Paleoclimates in Central and South America since 18,000 BP based on pollen and lake-level records. Quaternary Science Reviews 8, 1-24.

Markgraf, V. , Dodson, J.R. , Kershaw, A.P. , McGlone, M.S. and Nicolls, N. 1992: Evolution of late Pleistocene and Holocene climates in the circum-South Pacific land areas. Climate Dynamics 6, 193-211.

Martin, L. , Fournier, M. , Mourguiart, P. , Sifeddine, A. , Turcq, B. , Absy, M.L. and Flexor, J-M. 1993: Southern oscillation signals in South American paleoclimatic data of the last 7000 years. Quaternary Research 39, 338-46.

10.

Mercado, M. 1982: Geologia de la Hoja Laguna del Negro Francisco. Carto Geológica de Chile 1:100,000, no. 56.

11.

Messerli, B. , Ammann, C. , Geyh, M.A. , Grosjean, M. , Jenny, B. , Kammer, K. and Vuille, M. 1996: The problem of the 'Andean Dry Diagonal': Current precipitation, late Pleistocene snow line, and lake level changes in the Atacama Altiplano (18°S-28/29°S). Bamberger Geographische Schriften 15, 17-35.

12.

Müller, G. , Irion, G. and Forstner, U. 1972: Formation and diagenesis of inorganic Ca-Mg carbonates in the lacustrine environment. Naturwissenschaften 59, 158-64.

13.

Segerstrom, K. 1968: Geologia de las Hojas Copiapó y Ojos del Salado, Provincia de Atacama. Instituto de Investigaciónes Geológicas Chile , Boletin 24.

14.

Smoot, J.P. and Lowenstein, T.K. 1991: Depositional environments of non-marine evaporites. In Melvin, J. , editor, Developments in sedimentology 50, Amsterdam : Elsevier, 189-347.

15.

Stoertz, G.E. and Ericksen, G.E. 1974: Geology of Salars in Northern Chile. Geological Survey Prof. Paper 811, 1-65.

16.

Valero Garcés, B. , Grosjean, M. , Schwalb, A. , Geyh, M.A. , Messerli, B. and Kelts, K. 1996: Limnogeology of Laguna Miscanti: evidence for mid to late Holocene moisture changes in the Atacama Altiplano (Northern Chile). Journal of Paleolimnology (special issue AMQUA, Vol. II), 16, 1-21.

17.

Veit, H. 1994: Jungquartäre Landschafts und Klimaentwicklung am Südrand der Atacama (Norte Chico, Chile). Habil. Thesis, University of Bayreuth, 260 pp.

18.

Villagrán, C. and Varela, J. 1990: Palynological evidence for increased aridity on the central Chilean coast during the Holocene. Quarternary Research 34, 198-207.

19.

Vuille, M. 1996: Zur raumzeitlichen Dynamik von Schneefall und Ausaperung im Bereich des südlichen Altiplano, Südamerika. Geographica Bernensia G45.

20.

Vuille, M. and Ammann, C. 1996: Regional snowfall patterns in the high, arid Andes (South America). Climatic Change, in press.