Omnipresent authigenic carbonates distort Arctic radiocarbon chronology

The dataset submitted provides a photo documentation on the preservation status of Neogloboquadrina pachyderma shells in sediments of two Arctic sediment cores (PS72/413-3 and PS2185-6). In the accompanying paper different preservation indices (PI_1-3) were introduced to describe the progressive diagenetic alteration from 1 to 3, and the documentation helps to understand how the shells were assigned to the different categories. The data set also serves as a guide for future shell-based work, showing differences between biologically precipitated shell and authigenic overgrowth. This dataset is the first comprehensive documentation that illustrates diagenitic calcite on N. pachyderma shells and as isolated sedimentary crystals at none-seepage sites in the Arctic. Furthermore, the shells and crystals that were used for radiocarbon dating and isotope analyses as shown in the accompanying paper are illustrated in respective documentary files.