Paleohydrology of the Santiaguillo Basin (Mexico) since late last glacial and climate variation in southern part of western subtropical North America
Résumé
Stratigraphy, geochemistry and radiocarbon dating of a succession of sediment in the Santiaguillo Basin (centralnorthernMexico) help reconstruct themillennial-scale dynamics of hydrological variability that occurred in thesouthern part ofwestern subtropical North America since the late last glacial. Runoffwas generally above averageduring the late last glacial from ~27 to 18 ka. Following this interval, runoff decreased and deposition ofauthigenic carbonate and aeolian transported sediment increased until ~4 ka. Heinrich 1 and 2, and YoungerDryas were intervals of reduced runoff and increased aeolian activity. The wetter climate of central-northernMexico and arid conditions in north–northwestern Mexico during the late last glacial were probably related toformation of tropical cyclones in the eastern North Pacific during the autumn with restricted rainfall swathsand an absent/weaker North American Monsoon. Enhanced North American Monsoon and tropical cycloneswith expanded rainfall swaths brought more summer and autumn precipitation to a broader region extendingfrom the central-northern Mexico to the continental interiors of southwestern US during the early Holocene.