Humid Pleistocene−Holocene transition and early Holocene in sub-tropical northern Mexico and possible Gulf of California forcing
Résumé
A new geochemical record from the paaleolake Santiaguillo documents the hydrological variability of subtropicalnorthern Mexico over the last ∼14 cal. ka. Summer-season runoff, lake water salinity and deposition ofsediments by aeolian activity were reconstructed from concentrations of K, Ca and Zr/K in bulk sediments.More-than-average runoff during c. 12.3–9.3 cal. ka BP represented an interval of enhanced summer precipitation.Arid intervals of c. 14–12.3 cal. ka BP and c. 6–4.3 cal. ka BP were characterized by average and more-thanaverageaeolian activity. Comparison with proxy records of summer as well as winter precipitation from tropicaland sub-tropical North America and sea surface temperatures from the Atlantic and Pacific provides insight intothe source of moisture and possible forcing. The wet Pleistocene−Holocene transition and early Holocene wascontemporary with warmer conditions in the Gulf of California. We suggest that the Atlantic had minimalinfluence on the summer precipitation of the western part of sub-tropical northern Mexico and that the source ofmoisture was dominantly Pacific.