Holocene paleohydrology of the Etzatlán-Magdalena basin in western-central Mexico and evaluation of main atmospheric forcings

Sediments deposited in the Etzatlán-Magdalena Basin were analyzed to reconstruct the paleohydrological variations and generate a new Holocene paleoclimate record for the less studied western part of central Mexico. Concentration of Ti, abundance of CaCO3, Zr/Ti ratio and TOC/Ti ratio were compared with their average values to infer variations in runoff, lake water salinity, transportation of clastic minerals by aeolian activity and total organic productivity. In general, conditions were wetter during ~ 9.6-5.7 ka (early-middle Holocene) and ~ 2.2-0.7 ka (late Holocene) compared to ~ 5.7-2.2 ka (middle-late Holocene). Transportation of above-average amounts of Zr-bearing clastic minerals from an arid watershed and deposition of the highest abundance of CaCO3 at ~ 3.5-2.8 ka occurred within the drier interval of middle-late Holocene. Except for the interval of ~ 2.2-0.7 ka, the El Niño Southern Oscillation (ENSO) and Inter Tropical Convergence Zone (ITCZ) controlled summer precipitation forced the hydrological variations. The Etzatlán-Magdalena Basin remained wet and some sites in central Mexico were dry over a large part of ~ 2.2-0.7 ka. The activity of tropical cyclones and frontal systems may have increased in the northeastern Pacific during this interval of enhanced ENSO. Either of them, or the combination of both, possibly contributed more autumn and winter precipitation to western-central Mexico.