Element maps from 5x 10 cm sections generated using the Zeiss Sigma HD Field Emission Gun Analytical SEM at Cardiff University. Maps come from sections within the early Miocene pelagic interval situated directly below the Nicobar Fan succession at IODP Site U1480 in the Eastern Equatorial Indian Ocean (for more information see published report, https://doi.org/10.1016/j.epsl.2017.07.019). These specific sections were chosen to examine the depositional environments associated with transitions from red clays to white chalk, which demonstrate distinct banding at the micro and macro scale.

Middle Miocene terrestrial climate reconstructions from fossil plant remains. 197 sites are reconstructed from across the globe. These are presented with latitude-longitude co-ordinates (both modern and palaeo), published minimum and maximum ages of each site and a 1/0 column to denote those sites relating to the mid Miocene climatic optimum. Reconstructed variables are: bio1 (mean annual temperature in °C), bio8 (mean temperature of the wettest quarter in °C), bio10 (mean temperature of the warmest quarter in °C), bio11 (mean temperature of the coldest quarter in °C), bio12 (mean annual precipitation in mm), bio14 (Precipitation of Driest Month in mm), bio17 (Precipitation of Driest Quarter in mm), bio18 (Precipitation of Warmest Quarter in mm) and bio19 (Precipitation of coldest Quarter in mm). bios are presented as an optima with 0.5 and 0.95 uncertainty

Stable isotope data of organic carbon, nitrogen and sulfur as well as trace elements are used to explore how proxies with differing residence times in seawater respond to changes in the basin’s connectivity to the open ocean. The results show that species with a short residence time, such as nitrate and rare earth elements, may be more sensitive to geologically brief fluctuations in oceanographic conditions than long-lived species like sulfate. Details about the methodology and sampling strategy can be found in Stu¨eken, E.E., Viehmann, S. and Hohl, S.V., 2023, ACS Earth and Space Chemistry, 7(7), pp.1337-1349.

This dataset comprises palynological counts on sediments from IODP Expedition 374 Site U1521 to the Ross Sea, collected on the RV JOIDES Resolution. Marine palynomorphs are counted in 23 samples, and 7 samples were counted for terrestrial palynomorphs (pollen and spores). Shipboard biostratigraphy and magnetostratigraphy suggests the samples are early Miocene in age (McKay et al., 2019, Proceedings of the International Ocean Discovery Program).

Count data (original counts and percentage abundances) from nannofossil assemblage analysis of Early Miocene samples. These form the prime data for a paper submitted to Palaeogeography, Palaeoclimatology, Palaeoecology (Young et al. submitted, 2019).

Data derived from NERC Grant NE/N001621/1. Geographical Area - DSDP/ODP/IODP Sites 516, 1138, 925, 242, 1338, 871, 872

This dataset comprises 40Ar/39Ar dated detrital hornblende grains for 5 samples from IODP Expedition 374 Site U1521 to the Ross Sea, collected on the RV JOIDES Resolution. Shipboard biostratigraphy and magnetostratigraphy suggests the samples are early Miocene in age (McKay et al., 2019, Proceedings of the International Ocean Discovery Program). These data can be compared to terrestrial geochronological data, allowing the changing provenance of the sediments to be traced.

This dataset comprises zircon U-Pb data on 11 samples, each containing ~90-150 individual grains. This method was applied to sediment samples from IODP Expedition 374 Site U1521 to the Ross Sea, collected on the RV JOIDES Resolution. Shipboard biostratigraphy and magnetostratigraphy suggests the samples are mainly early Miocene in age (McKay et al., 2019). The uppermost samples do, however, include younger Plio-Pleistocene sediments. Samples were measured using an Agilent 7900 laser ablation inductively-coupled plasma mass spectrometer (LA-ICP-MS) with a 25-35 µm pit diameter in the London Geochronology Centre at University College London.

We report sedimentary coatings and fish teeth neodymium isotope values – tracers for water-mass mixing – from deep-water International Ocean Discovery Program (IODP) Site U1438 (4.7 km water depth) in the Philippine Sea, northwest Pacific Ocean. The time period encompasses the last 20 million years.

This dataset comprises 35 samples analysed for clay mineralogy from IODP Expedition 374 Site U1521 to the Ross Sea, collected on the RV JOIDES Resolution. Shipboard biostratigraphy and magnetostratigraphy suggests the samples are mainly early Miocene in age (McKay et al., 2019, Proceedings of the International Ocean Discovery Program). The uppermost samples do, however, include younger Plio-Pleistocene sediments.