Beschreibung: This dataset includes measurements on mixed layer planktonic foraminifera from IODP/ODP sites for boron isotopes and trace elements. Boron isotopes were measured after column chemistry and solution analyses on a Neptune multi collector ICPMS, while trace elements were measured on pre-columned aliquots of the same samples, using Element XR ICP-MS. Furthermore, the dataset includes the seawater pH and atmospheric CO2 calculated from B isotopes measurements and Mg/Ca-temperature estimates, for no-vital effect treatment (T. sac-vital effect corrections at Eocene d11Bsw conditions result in d11B offsets within analytical uncertainty), and no pH correction on Mg/Ca-temperature relationship (assuming T. sac like species). Carbonate system calculations incorporate MyAMI ion-pairing corrections (https://github.com/MathisHain/MyAMI), and surface Omega values specific for the Eocene and the paleo-latitude of the core location. Propagation of uncertainties for pH and CO2 is completed through 1000 Monte Carlo simulations.

Beschreibung: This dataset collection includes boron isotope, Mg/Ca, and Al/Ca data from planktonic foraminifera, reconstructed sea surface temperature, seawater pH and atmospheric CO2 concentrations, calculated Global Mean Temperature and Climate Sensitivity estimates, and recalculated seawater pH and atmospheric CO2 estimates from published planktonic foraminiferal boron isotope data.

Beschreibung: The dataset includes time series of global mean temperature for the Eocene, using a combination of sea surface temperature reconstructions and model derived estimates of global mean temperatures. These are coupled to the atmospheric CO2 reconstructions, translated into CO2 forcing relative to preindustrial, to calculate the evolving climate sensitivity for the Eocene. Both equilibrium climate sensitivity and earth system sensitivity are provided.

Beschreibung: In this dataset, we compile published records of seawater pH and atmospheric CO2 from foraminiferal δ11B are re-calculated using our current constrains and processing scenarios for the Eocene, for consistency to the new data. The re-calculation includes no vital effect treatment (for T. sac like species of planktonic foraminifera the offset in d11B at Eocene d11Bsw conditions is smaller than analytical uncertainty), no pH correction on Mg/Ca-temperature relationship (T. sac like species) and incorporating MyAMI for carbonate system calculations (https://github.com/MathisHain/MyAMI).

Beschreibung: The Early Eocene Climate Optimum (EECO, which occurred about 51 to 53 million years ago)1, was the warmest interval of the past 65 million years, with mean annual surface air temperature over ten degrees Celsius warmer than during the pre-industrial period2,3,4. Subsequent global cooling in the middle and late Eocene epoch, especially at high latitudes, eventually led to continental ice sheet development in Antarctica in the early Oligocene epoch (about 33.6 million years ago). However, existing estimates place atmospheric carbon dioxide (CO2) levels during the Eocene at 500–3,000 parts per million5,6,7, and in the absence of tighter constraints carbon–climate interactions over this interval remain uncertain. Here we use recent analytical and methodological developments8,9,10,11 to generate a new high-fidelity record of CO2 concentrations using the boron isotope (δ11B) composition of well preserved planktonic foraminifera from the Tanzania Drilling Project, revising previous estimates6. Although species-level uncertainties make absolute values difficult to constrain, CO2 concentrations during the EECO were around 1,400 parts per million. The relative decline in CO2 concentration through the Eocene is more robustly constrained at about fifty per cent, with a further decline into the Oligocene12. Provided the latitudinal dependency of sea surface temperature change for a given climate forcing in the Eocene was similar to that of the late Quaternary period13, this CO2 decline was sufficient to drive the well documented high- and low-latitude cooling that occurred through the Eocene14. Once the change in global temperature between the pre-industrial period and the Eocene caused by the action of all known slow feedbacks (apart from those associated with the carbon cycle) is removed2,3,4, both the EECO and the late Eocene exhibit an equilibrium climate sensitivity relative to the pre-industrial period of 2.1 to 4.6 degrees Celsius per CO2 doubling (66 per cent confidence), which is similar to the canonical range (1.5 to 4.5 degrees Celsius15), indicating that a large fraction of the warmth of the early Eocene greenhouse was driven by increased CO2 concentrations, and that climate sensitivity was relatively constant throughout this period.

Beschreibung: IODP Expedition 350 was the first to be drilled in the rear part of the Izu-Bonin, although several sites had been drilled in the arc axis to fore-arc region; the scientific objective was to understand the evolution of the Izu rear arc, by drilling a deep-water volcaniclastic section with a long temporal record (Site U1437). The Izu rear arc is dominated by a series of basaltic to dacitic seamount chains up to ~100-km long roughly perpendicular to the arc front. Dredge samples from these are geochemically distinct from arc front rocks, and drilling was undertaken to understand this arc asymmetry. Site U1437 lies in an ~20-km-wide basin between two rear arc seamount chains, ~90-km west of the arc front, and was drilled to 1804 m below the sea floor (mbsf) with excellent recovery. We expected to drill a volcaniclastic apron, but the section is much more mud-rich than expected (~60%), and the remaining fraction of the section is much finer-grained than predicted from its position within the Izu arc, composed half of ashes/tuffs, and half of lapilli tuffs of fine grain size (clasts 〈3 cm). Volcanic blocks (〉6.4 cm) are only sparsely scattered through the lowermost 25% of the section, and only one igneous unit was encountered, a rhyolite peperite intrusion at ~1390 mbsf. The lowest biostratigaphic datum is at 867 mbsf (~6.5 Ma), the lowest palaeomagnetic datum is at ~1300 mbsf (~9 Ma), and the rhyolite peperite at ~1390 mbsf has yielded a U–Pb zircon concordia intercept age of (13.6 + 1.6/−1.7) Ma. Both arc front and rear arc sources contributed to the fine-grained (distal) tephras of the upper 1320 m, but the coarse-grained (proximal) volcaniclastics in the lowest 25% of the section are geochemically similar to the arc front, suggesting arc asymmetry is not recorded in rocks older than ~13 Ma.