Global analysis reveals climatic controls on the oxygen isotope composition of cave drip water

Andy Baker , Andreas Hartmann (1) , Wuhui Duan , Stuart Hankin , Laia Comas-Bru , Mark O Cuthbert , Pauline C Treble , Jay Banner , Dominique Genty (2) , Lisa M Baldini , Miguel Bartolomé , Ana Moreno , Carlos Pérez-Mejías , Martin Werner

1 University of Freiburg [Freiburg]
2 EPOC - Environnements et Paléoenvironnements OCéaniques

The oxygen isotope composition of speleothems is a widely used proxy for past climate change. Robust use of this proxy depends on understanding the relationship between precipitation and cave drip water δ 18 O. Here, we present the first global analysis, based on data from 163 drip sites, from 39 caves on five continents, showing that drip water δ 18 O is most similar to the amount-weighted precipitation δ 18 O where mean annual temperature (MAT) is < 10°C. By contrast, for seasonal climates with MAT > 10°C and < 16°C, drip water δ 18 O records the recharge-weighted δ 18 O. This implies that the δ 18 O of speleothems (formed in near isotopic equilibrium) are most likely to directly reflect meteoric precipitation in cool climates only. In warmer and drier environments, speleothems will have a seasonal bias toward the precipitation δ 18 O of recharge periods and, in some cases, the extent of evaporative fractionation of stored karst water.

Domaines: Sciences de l'environnement

Andy Baker, Andreas Hartmann, Wuhui Duan, Stuart Hankin, Laia Comas-Bru, et al.. Global analysis reveals climatic controls on the oxygen isotope composition of cave drip water. Nature Communications, 2019, 10, ⟨10.1038/s41467-019-11027-w⟩. ⟨hal-03089444⟩