Résumé
This paper presents the first Lateglacial/Holocene (the last 13 500 cal a bp) ostracod delta (super 18) O record to infer hydroclimate variability in the Southern French Alps. Cytherissa lacustris (delta (super 18) O (sub sp) ) shells extracted from the sediments of Lake Allos allowed a reconstruction of delta (super 18) O (sub lake water) (delta (super 18) O (sub lw) ) except for the interval 5800-2800 cal a bp. The shape of the Younger Dryas (YD) clearly differed from records documented in the northern Alps. First, delta (super 18) O (sub lw) values remained close to modern values before a marked drop ca. 12 000 cal a bp. Then, after several oscillations, delta (super 18) O (sub lw) values increased, reaching the highest value of the record ca. 6100 cal a bp during a thermal optimum for this latitude. Finally, low delta (super 18) O (sub lw) values occurred from 450 to 100 cal a bp during the Little Ice Age (LIA) following the Medieval Climate anomaly. At the beginning of the YD, delta (super 18) O (sub lw) probably reflected changes in local glacier dynamics and precipitation sources. The following decrease in delta (super 18) O (sub lw) values was associated with higher freshwater inputs during the second half of the YD. During the LIA, the low delta (super 18) O values are consistent with a higher torrential activity and lower air temperatures. Abstract Copyright (2022), John Wiley & Sons, Ltd.