U-Pb calcite geochronology, EPR, geochemistry, and C-O-Sr isotopes of Africano marbles in the Seferihisar (İzmir, Türkiye)

Official URL: https://dx.doi.org/10.55730/1300-0985.1977

The Africano marbles (Africano Verde and Bigio Africano) extracted from the region of Sığacık (ancient Teos) region and its surroundings were widely used and even traded in construction and decorative items throughout the Roman period due to their brecciated and colourful appearance. There are two different types of Africano marble, the first consisting of marble breccias embedded in a dark matrix. In this type, the marble breccias show micritic, microsparitic, and sometimes sparitic textures formed by coarse-grained calcite, while the dark matrix consists of chlorite and/or serpentine minerals. The second type is Bigio Africano, which consists of grey-blue homogeneous limestones, composed mainly of microsparitic and sparitic calcite. The geochemical and isotopic characteristics of Africano marbles extracted from three different quarries indicate that these marbles generally originate from carbonates deposited in an open ocean environment. Africano marbles can be easily distinguished from other brecciated marbles (Marmor Sagarium, Marmo Docimeion) by their grain sizes, the textural differences in the marble breccias and their geochemical properties. The same distinction, however, does not apply to Bigio Africano. This grey marble is very similar to other grey marbles used in ancient times. The ⁸⁷Sr/⁸⁶Sr isotope ratios in the whole marble samples vary between 0.70723 (±0.0000059) and 0.70956 (±0.0000058). The δ¹³C isotope values range from –4.96‰ (±0.08) to 3.36‰ (±0.08), while the δ¹⁸O isotope values range from –11.17‰ (±0.10) to –5.41‰ (±0.10). For the first time in this study, the U-Pb calcite age of Africano marbles was determined to be 73.3 ± 11 Ma, and this age is compatible with the fossil ages of limestones from the Bornova flysch zone. All spectroscopic characterization studies and age analyses performed on the Africano marbles will be an important data source for researchers investigating the source of these marbles in the future.