Palynological data for Miocene sediments collected at Site U1521 during International Ocean Discovery Program (IODP) Expedition 374 to the Ross Sea, Antarctica

Sample processing was performed at Utrecht University, following standard techniques of the Laboratory of Palaeobotany and Palynology. Samples were oven-dried and weighed (~15 g dry weight sediment each). One Lycopodium clavatum tablet with a known amount of marker spores was added for quantification of palynomorph abundances (Wood et al., 1996). Samples were treated with 10% HCl (Hydrochloric acid) and cold 38% HF (Hydrofluoric acid), then sieved over a 10 μm mesh with occasional mild ultrasonic treatment. To avoid any potential processing-related preservation bias, no oxidation or acetolysis was carried out. The processed residue was transferred to microscope slides using glycerine jelly as a mounting medium, and 2 slides were analysed per sample at 400× magnification. Slides were examined for detailed marine (dinoflagellate cysts, acritarchs and other aquatic palynomorphs) and screening-level terrestrial (pollen and spore) analysis at Utrecht University, with a subsequent detailed analysis for terrestrial palynomorphs on a sub-set of seven samples undertaken at GNS Science. Of the 23 palynological samples analysed for dinocysts, two contained <60 dinocysts (594.48 and 567.75 mbsf) and one was almost barren (yielding only 12 in situ dinocysts, 374.9 mbsf). The low abundance samples are included in our dataset; however, because of the low dinocyst yield, careful interpretation is required. Pollen and spore identification followed taxonomic compilations (Raine et al. 2011; Prebble 2016), augmented by key Antarctic literature (Askin, 2000; Askin and Raine 2000; Truswell, 1983). For pollen and spores, scanning continued until an entire cover slide was completed, or a 100 count reached. Dinocysts were identified based on a taxonomical index (Fensome and Williams, 2004) and informally and formally described species in the literature (Hannah et al., 2000; Hannah, 2006; Clowes et al., 2016; Bijl et al., 2018). Methods and full references can be found at the bottom of the data tables.

INSPIRE Implementing rules laying down technical arrangements for the interoperability and harmonisation of Geology

Commission Regulation (EU) No 1089/2010 of 23 November 2010 implementing Directive 2007/2/EC of the European Parliament and of the Council as regards interoperability of spatial data sets and services