A record of Holocene summer-season palaeohydrological changes from the southern margin of Chihuahua Desert (Mexico) and possible forcings

Abstract

Proxy records of runoff, lake water salinity and aeolian activity, reconstructed by analyzing the concentrations of Ti, Ca and Zr/Ti in the sediments of palaeolake Las Cruces, provide information about millennial-scale summer season palaeohydrological changes at the southern margin of Chihuahua Desert over the last 8.4 cal. kyr BP. The data indicate generally higher-than-average runoff between c. 8.4 and 5 cal. kyr BP, correlative to the early Holocene Thermal Maximum. Except for the c. 2.2–2 cal. kyr BP humid event, runoff was lower than average over the last c. 5 cal. kyr BP. Latitudinal shifts in average position of the Inter-Tropical Convergence Zone (ITCZ) caused by long-term changes in summer insolation was the principal forcing behind the varying summer season precipitation and El Niño Southern Oscillation (ENSO) activity may explain some of the hydrological variability (e.g. higher-than-average summer precipitation during c. 2.2–2 cal. kyr BP). In general, the basin received more runoff during the periods of less frequent and weak ENSO, similar to the modern response to ENSO activity of the region. Significant increases in lake water salinity and aeolian activity over the last 2 cal. kyr BP correspond to stronger and more frequent ENSO during the late Holocene.