Late Pleistocene–Holocene environmental fluctuations of southern Chihuahua Desert, Mexico

Paleoenvironmental reconstructions from the Mexican Chihuahua Desert based on biological proxies are scarce, creating a gap in our understanding of the ecological responses to climate change in this water-scarce region. Here, we present a paleoenvironmental reconstruction based on geochemical data and biological proxies such as ostracods and ephippia from cladocerans from the Santa Clara basin, at the southern Chihuahua Desert, during the last 18.7 cal ka. Overall, cold and humid conditions between 18.7 and 15 cal ka BP prevailed in the Santa Clara region without ostracod preservation. During the warmer Bølling-Allerød, L. axalapasco presented higher productivity; however, this species did not occur during the colder Younger Dryas. The early Holocene was marked by a general trend towards warmer and dryer conditions, and a sedimentary hiatus was detected from 10.7 to 6.4 cal ka BP. Subsequently, when the North American Monsoon reached its maximum extension, ostracods exhibit their maximum total abundance during 6–4.8 cal ka BP, indicating warmer and shallower lake conditions. The presence of only females of L. bradburyi between 4–2 cal ka BP possibly suggests lower lake water temperatures associated with enhanced winter precipitation under El Niño type conditions. Finally, during the last 2 cal ka ephippia, L. axalapasco females and geochemical data suggest the driest period of the record as the ITCZ continued moving southwards. This work reveals the marked sensitivity of southern Chihuahua Desert ecosystems to the climatic shifts that occurred since the Last Glacial Maximum, and this perhaps indicates their vulnerability to future global warming reducing monsoonal precipitation.