Stable Oxygen and Carbon Isotope Composition of Holocene Mytilidae from the Camarones Coast (Chubut, Argentina): Palaeoceanographic Implications

BORETTO, G.; BANESCHI, I.; BINI, M.; ZANCHETTA, G.; REGATTIERI E.; GUIDI, M.; RAGAINI, L.; DALLAI, L.; CONSOLONI, I.; ISOLA, I.; TERRASI, F.

WATER

Water Editorial - MDPI

Lugar: Basel; Año: 2020 vol. 12 p. 2 - 17

2073-4441

The stable isotope composition of living and of Holocene Mytilidae shells was measuredin the area of Camarones (Chubut, Argentina). The most striking results were the high δ18O valuesmeasured in samples older than ca. 6.1 cal ka BP. In the younger samples, the δ18O values remainedsubstantially stable and similar to those of living specimens. Analysis of the data revealed thepossibility for this isotopic shift to be driven mainly by changes in temperature probablyaccompanied by minor changes in salinity, suggesting cooler seawater before 6.1 cal ka BP, with amaximum possible temperature shift of ca. 5 °C. A possible explanation of this change can be relatedto a northward position of the confluence zone of the Falkland and Brazilian currents. This isconsistent with the data obtained in marine cores, which indicate a northerly position of theconfluence in the first half of the Holocene. Our data are also in line with the changes in windstrength and position of the Southern Westerlies Wind, as reconstructed in terrestrial proxies fromthe Southernmost Patagonia region.