Quick Search:    advanced search

GSW Home   GeoRef Home   My GSW Alerts   Contact GSW   About GSW   Journals List   Help

This Article Figures Only Full Text Full Text (PDF) Alert me when this article is cited Alert me if a correction is posted Citation Map Services Email this article to a friend Similar articles in this journal Similar articles in ISI Web of Science Alert me to new issues of the journal Download to citation manager Citing Articles Citing Articles via HighWire Citing Articles via ISI Web of Science (27) Citing Articles via Google Scholar Google Scholar Articles by Rech, J. A. Articles by Betancourt, J. L. Search for Related Content GeoRef GeoRef Citation

Late Quaternary paleohydrology of the central Atacama Desert (lat 22°–24°S), Chile

¹ Department of Geosciences and Desert Laboratory, University of Arizona, 1675 West Anklam Road, Tucson, Arizona 85745, USA
² U.S. Geological Survey and Desert Laboratory, University of Arizona, 1675 West Anklam Road, Tucson, Arizona 85745, USA

In northern Chile, precipitation in the High Andes (>3500 m) recharges groundwater systems that flow down the Pacific slope and feed large aquifers in the hyperarid Atacama Desert. Wetlands, which are often found along the base of the Andes, mark locations where the water table intersects the land surface. At these locations, paleo–wetland deposits, which are present as terraces between 3 and 20 m above modern wetlands, record past water-table heights along the Andean front and are used to reconstruct changes in groundwater discharge. Paleo–wetland deposits in the central Atacama Desert (lat 22°–24°S) record an episode (>15.4–9 ka) of high water tables followed by an episode (8–3 ka) of moderately high water tables. Elevated water tables result from increased groundwater discharge and ultimately from enhanced recharge in the Andes. The concordance of results from three separate hydrologic systems suggests that changes in groundwater discharge and recharge are regional and reflect climatic fluctuations. This interpretation is supported by close agreement with other paleoclimatic records in the region. The periods of greater groundwater discharge were separated by episodes (9–8 and 3–0 ka) of significant groundwater lowering and stream incision, implying greatly diminished discharge.

The central Atacama and Andes (lat 22°– 24°S) receive precipitation mainly from moist air masses transported from the Amazon Basin by the South American Summer Monsoon (SASM). Increases in groundwater recharge are therefore thought to reflect an increase in the frequency and/or moisture content of SASM air masses crossing the Andes. Fluctuations in SASM precipitation have previously been linked to summer insolation in the Southern Hemisphere. The wettest period in the central Atacama (>15.4–9 ka), however, coincides with a minimum in austral-summer insolation at 10 ka, suggesting that regional summer insolation is not a dominant influence on the SASM. Instead, intensification of the SASM may be linked to extraregional forcings such as the Walker Circulation.

Key Words: Atacama Desert • wetlands • springs • paleohydrology • South America

This article has been cited by other articles:

				P. L. Nester, E. Gayo, C. Latorre, T. E. Jordan, and N. Blanco Perennial stream discharge in the hyperarid Atacama Desert of northern Chile during the latest Pleistocene PNAS, December 11, 2007; 104(50): 19724 - 19729. [Abstract] [Full Text] [PDF]

				J. A. Rech, B. S. Currie, G. Michalski, and A. M. Cowan Neogene climate change and uplift in the Atacama Desert, Chile Geology, September 1, 2006; 34(9): 761 - 764. [Abstract] [Full Text] [PDF]

				A. J. HARTLEY, G. CHONG, J. HOUSTON, and A. E. MATHER 150 million years of climatic stability: evidence from the Atacama Desert, northern Chile Journal of the Geological Society, May 1, 2005; 162(3): 421 - 424. [Abstract] [Full Text] [PDF]

				A. E. Mather and A. Hartley Flow events on a hyper-arid alluvial fan: Quebrada Tambores, Salar de Atacama, northern Chile Geological Society, London, Special Publications, January 1, 2005; 251(1): 9 - 24. [Abstract] [PDF]

				E. S.J. Dollar Fluvial geomorphology Progress in Physical Geography, September 1, 2004; 28(3): 405 - 450. [PDF]

				Groundwater-sapping origin for the giant quebradas of northern Chile Geology, July 1, 2004; 32(7): 605 - 608.

				C. Latorre, J. L. Betancourt, K. A. Rylander, and J. Quade Vegetation invasions into absolute desert: A 45;th000 yr rodent midden record from the Calama-Salar de Atacama basins, northern Chile (lat 22{degrees}-24{degrees}S) GSA Bulletin, March 1, 2002; 114(3): 349 - 366. [Abstract] [Full Text] [PDF]