Lateglacial-Middle Holocene stable isotope records in two coeval stalagmites from the Bihor Mountains, NW Romania

Abstract

Oxygen and carbon stable isotope records of two stalagmites from NW Romania provide a continuous climatic record between 14.8 and 5.6 ka BP. The chronology is established by 21 TIMS uranium series ages. Uncertainties in the isotope chronology range between ą20 and ą100 yr. The d18 O values are positively correlated with temperature, whereas d13 C fluctuations suggest changes in soil CO2 production. Lateglacial deposition of both stalagmites started at ~14.8 ka BP. The d18 O records subsequently show a slow decline in temperatures until 12.6 ka BP. Three warmer periods with increased soil productivity occurred at 14.5-13.9 ka BP, 13.6-13.2 ka BP, and 12.9-12.6 ka BP. Lower d18 O and high d13 C values between 12.6 and 11.4 (11.7) ka BP indicate a cold and dry climate during the Younger Dryas (GS-1). During the Early Holocene, three short cold intervals are marked on the d18 O profiles at 11.0-10.6, 10.5-10.2 and 9.4-9.1 ka BP. For the remainder of the Holocene sequence, the d18 O records show less variation between 9 and 7.8 ka BP and gradual warming from 7.6-5.6 ka BP. The speleothem records correlate with the Greenland ice core records and with other proxies throughout Europe and the North Atlantic region.