14C chronology and stable isotopes on Lymnaea viatrix shells in northwest Patagonia, Argentina. Do they express the Antarctic climatic reversal?

Abstract

A multi-isotope environmental record comprising an upper section of the late Pleistocene and the lower and middle Holocene, including isotopic data on 30 samples of peat, marl, tufa, Lymnaea viatrix shells, and Hippidion sp. teeth, is described from a 15 m profile at Arroyo Leuto Caballo, Neuquén Province, Argentina. The chronology of the Pleistocene sequence was derived from five modeled 14C ages. δ18O of L. viatrix, assumed as a proxy for δ18O of meteoric water isotopic composition and thus sensitive to air temperature changes, showed a warming period from 14.03 cal ka BP until ca. 13.90 cal ka BP, followed by a rapid decline in temperature, attaining a minimum between 13.79 and 13.56 cal ka BP and a subsequent warming reestablishment. In addition, a “specular pattern” of δ13C of L. viatrix peaking in the same time span would be probably showing aridity. This pattern developed within the globally defined Antarctic Cold Reversal-ACR-time span (from 14.6–2.8 cal ka BP), and prior to the onset of the Huelmo Mascardi Cold Reversal episode, HCMR, from ca 13.30–1.87 cal ka BP. Given the characteristics and the time span covered, it could be related to a continental expression of the ACR event.