Environmental reconstructions based on aquatic and terrestrial snails originating from the Early Bronze Age and the Late Islamic Period– A stable isotope case study from the Al-Khashbah archaeological Site, Sultanate of Oman

Abstract

Fossil shells of terrestrial and aquatic snails provide important information for the reconstruction of the Early Bronze Age environmental conditions in the Sultanate of Oman. Terrestrial species can be used to reconstruct available and thus consumed vegetation and the origin of precipitation, while aquatic species are useful for temperature estimates. The aim of this study is to identify past environmental conditions by generating high-resolution stable isotope series from well-preserved aragonitic shells of gastropods. A total of seven shells of the terrestrial species Zootecus insularis and five aquatic snails, Melanoides tuberculata, from Al-Khashbah were sampled. Eight of them were dated to the Early Bronze Age and four belong to the Late Islamic period that can be used as a reference. Stable isotope data of carbon (δ13Cshell) of the terrestrial snails indicate a change in digested vegetation from C3 plants in the Early Bronze Age to C4 plants in the Late Islamic period. δ18Oshell data obtained by the fully aquatic snails (range of max. 1 ‰) suggests a habitat, e.g., groundwater, with a strong environmental buffering effect. Though sudden rainfall events followed by subsequent evaporation are not recorded in the isotope record, data suggest highly variable palaeoprecipitation regimes with different origins (Indian Ocean and Mediterranean).