ALBERT

Description: These datasets contain a six-year long record of shell morphology of the polar planktic foraminifera Neogloboquadrina pachyderma (sensu stricto) from near Palmer Station, Antarctica. The PARFLUX Mark 78H 21-sample trap was deployed in 170m water depth as part of the Palmer Long Term Ecological Research program (total water column depth 350 m, 64° 30'S, 66° 00'W). For manual analysis: Specimens were imaged using Olympus SZX7 transmitted light microscope, QImaging FAST 1394 camera and Q-Capture software. Image backgrounds were adjusted in Adobe PhotoshopCC 2015. Morphological parameters were measured using ImageProPlus 6.2. For automated analysis: Bulk samples measured using automated microscope and image analysis system that scans and captures images via a 12 MP Olympus CC12 camera attached to a Wild MZ3 incident light microscope (Analysis3.0)

Description: The application of transfer functions on fossil assemblages to reconstruct past environments is fundamentally based on the assumption of stable environmental niches in both space and time. We quantitatively test this assumption for six dominant planktic foraminiferal species (Globigerinoides ruber (pink), G. ruber (white), Trilobatus sacculifer, Truncorotalia truncatulinoides, Globigerina bulloides and Neogloboquadrina pachyderma) by contrasting reconstructions of species realised and optimum distributions in the modern and during the Last Glacial Maximum (LGM) using an ecological niche model (ENM; MaxEnt) and ordination framework. Global ecological niche models calibrated in the modern ocean have high predictive performance when projected to the LGM for sub-polar and polar species, indicating that the environmental niches of these taxa are largely stable at the global scale across this interval. In contrast, ENM's had much poorer predictive performance for the optimal niche of tropical-dwelling species, T. sacculifer and G. ruber (pink). This finding is supported by independent metrics of niche margin change, suggesting that niche stability in environmental space was greatest for (sub)polar species, with greatest expansion of the niche observed for tropical species. We find that globally calibrated ENMs showed good predictions of species occurrences globally, whereas models calibrated in either the Pacific or Atlantic Oceans only and then projected globally performed less well for T. sacculifer. Our results support the assumption of environmental niche stability over the last ~21,000 years for most of our focal planktic foraminiferal species and thus, the application of transfer function techniques for palaeoenvironmental reconstruction during this interval. However, the lower observed niche stability for (sub)tropical taxa T. sacculifer and G. ruber (pink) suggests that (sub)tropical temperatures could be underestimated in the glacial ocean with the strongest effect in the equatorial Atlantic where both species are found today.

Description: The Middle Eocene Climatic Optimum (MECO) at ca. 40 Ma is one of the largest of the transient Eocene global warming events. However, it is relatively poorly known from tropical settings since few sites span the entirety of the MECO event and/or host calcareous microfossils, which are the dominant proxy carrier for palaeoceanographic reconstructions. Ocean Drilling Program (ODP) Pacific Ocean Site 143-865 in the low-latitude North Pacific (Allison Guyot) has the potential to provide a useful tropical MECO reference but detailed stratigraphic and chronological constraints needed to evaluate its completeness were previously lacking. We have addressed this deficit by generating new high-resolution biostratigraphic, stable isotope and X-ray fluorescence (XRF) records spanning the MECO interval (~38.0-43.0 Ma) in two holes drilled at Site 143-865. XRF-derived strontium/calcium (Sr/Ca) and barium/strontium (Ba/Sr) ratio and Fe count records allow correlation between holes and reveal pronounced rhythmicity, enabling us to develop the first composite section for Holes 143-865B and 143-865C and a preliminary cyclostratigraphy for the MECO. Using this new framework, the sedimentary record is interpreted to be continuous across the event, as identified by a pronounced transient benthic foraminiferal δ¹⁸O shift of ~0.8‰. Calcareous microfossil biostratigraphic events from widely used zonation schemes are recognized, with generally good agreement between the two holes, highlighting the robustness of the new composite section and allowing us to identify planktic foraminiferal Zones E10-E15 and calcareous nannofossil Zones NP15-18. However, discrepancies in the relative position and ordering of several primary and secondary bioevents with respect to published schemes are noted. Specifically, the stratigraphic highest occurrences of planktic foraminifera Acarinina bullbrooki, Guembelitrioides nuttalli, and Morozovella aragonensis, and calcareous nannofossils Chiasmolithus solitus and Sphenolithus furcatolithoides and the lowest occurrence of Reticulofenestra reticulata, all appear higher in the section than would be predicted relative to other bioevents. We also note conspicuous reworking of older microfossils (from planktic foraminiferal Zones E5-E9 and E13) into younger sediments (planktic foraminiferal Zones E14-15) within our study interval consistent with reworking above the MECO interval. Regardless of reworking, the high-quality XRF records enable decimeter scale correlation between holes and highlight the potential of Site 143-865 for constraining tropical environmental and biotic changes, not just across the MECO but also throughout the Paleocene and early-to-middle Eocene interval.

Description: The major Cenozoic shift from a shallow (~3‒4 km) to deep (~4.5 km) calcite compensation depth (CCD) occurred at the Eocene-Oligocene Transition (EOT; ~34 Ma), suggesting a strong relationship between calcium carbonate (CaCO3) cycling and Antarctic glaciation. To further investigate the linkages between these two events, detailed records of deep-sea carbonate content, and bulk sediment and benthic foraminiferal stable isotope records are needed. This dataset contains bulk sediment stable isotope and carbonate content records from eight sites in the eastern equatorial Pacific (ODP Leg 199 and IODP Expedition 320). These records were used to reconstruct the depth of the calcite compensation depth (CCD) across the Eocene-Oligocene Transition. The projected depth of the CCD is included in this dataset. In addition, this dataset contains a monospecific epifaunal benthic foraminiferal stable isotope stratigraphy from IODP Expedition 320 Site U1334, in the eastern equatorial Pacific, across the Eocene-Oligocene Transition.

Description: Here we provide extensive micropaleontological and geochemical dataset of shallow-marine deposits that includes palynology and palynomorph component, carbonate fine-fraction stable-isotope, benthic foraminiferal stable-isotope, X-ray fluorescence (XRF), and glycerol dialkyl glycerol tetraether (GDGT) data. Samples were originally collected from the Mossy Grove core, nearby Jackson, central Mississippi, US Gulf Coastal Plain, between August 19, 1991 and September 5, 1991 (Dockery III et al., 1991). The dataset was generated between October 2015 and June 2019 and covers the latest Eocene and earliest Oligocene (~37.5-33.1 million years ago). These data were intended to yield unique multi-proxy records of the critical Eocene-Oligocene Transition, the most prominent climate event in the last 100 million years of Earth's history. Methods for age model, palynology and palynomorph component, carbonate fine-fraction stable-isotope, benthic foraminiferal stable-isotope, X-ray fluorescence (XRF), and glycerol dialkyl glycerol tetraether (GDGT) data follow De Lira Mota et al. (in review).

Description: Elemental composition of the sediment core was determined using two XRF techniques. 2,098 samples on the original core section were directly analyzed at a resolution of ~1.2 cm across the interval 17.1-109.4 m with a hand-held XRF analyzer at the core store of the Mississippi Department of Environmental Quality, in Jackson, Mississippi. A further 179 samples were collected every 20-30 cm downcore, spanning the interval 106.8-151.6 m, and were subsequently finely ground and dried before analysis as pressed powders in wax pellets. Pellets were analyzed with a Bruker S8 TIGER XRF spectrometer with an 8 min analysis time, at the School of Chemistry, University of Birmingham. We selected the (Al+Fe+K+Ti)/Ca ratio as a paleoenvironmental indicator of terrigenous-derived versus marine planktonic carbonate sediment 79,80. The two methodologies were cross-calibrated over an interval of overlap between 106.8 and 109.4 m, with a total of ~80 samples, spanning a range of compositions, cross-correlated from both analysis methods.

Description: Samples were processed for GDGTs at the Birmingham Molecular Climatology Laboratory, University of Birmingham. Lipids were extracted from ~10-15 g of homogenized sediment by ultrasonic extraction using dichloromethane (DCM):methanol (3:1). The total lipid extract was fractionated by silica gel chromatography using n-hexane, n-hexane:DCM (2:1), DCM, and methanol to produce four separate fractions, the last of which contained the GDGTs. Procedural blanks were also analyzed to ensure the absence of laboratory contaminants. Samples were filtered using hexane:isopropanol (99:1) through a 0.4 µm PTFE filter (Alltech part 2395), before being dried under a continuous stream of N2. Samples were then sent to the University of Bristol for analysis by LC-APCI-MS. HPLC-APCI-MS analyses were conducted at the National Environmental Isotope Facility, Organic Geochemistry Unit, School of Chemistry, University of Bristol, with a ThermoFisher Scientific Accela Quantum Access triple quadrupole MS in selected ion monitoring (SIM) mode. Normal phase separation was achieved using two ultra-high performance silica columns (Acquity UPLC BEH HILIC columns, 50 mm × ID 2.1 mm × 1.7 µm, 130 Å; Waters) were fitted with a 2.1 mm × 5 mm guard cartridge after Hopmans et al. (2016). The HPLC pump was operated at a flow rate of 200 µL min-1. GDGT determinations were based on single injections. A 15 µL aliquot was injected via an autosampler, with analyte separation performed under a gradient elution. The initial solvent hexane:iso-propanol (IPA) (98.2:1.8 v/v) eluted isocratically for 25 min, followed by an increase in solvent polarity to 3.5 % IPA in 25 min, and then by a sharp increase to 10 % IPA in 30 min (Hopmans et al., 2016). A 45 min washout period was applied between injections, whereby the column was flushed by injecting 25 µL hexane:isopropanol (99:1 v/v). GDGT peaks were integrated manually using Xcalibur software. In-house generated standard solutions were measured daily to assess system performance. One peat standard was run in a sequence for every 10 samples and integrated in the same way as the unknowns. Selected ion monitoring (SIM) was used to monitor abundance of the [M+H] + ion of the different GDGTs instead of full-scan acquisition in order to improve the signal-to-noise ratio and therefore yield higher sensitivity and reproducibility. SIM parameters were set to detect the protonated molecules of isoprenoid and branched GDGTs using the m/z (Schoon et al., 2013). The majority of sediments were found to contain a full range of both isoprenoid and branched GDGTs. Sea surface temperature (SST) estimations from GDGT assemblages are show based on two methodologies: the BAYSPAR Bayesian regression model of Tierney and Tingley (2014, 2015) using the 'analogue' version for deep-time applications; and, the OPTiMAL Gaussian process model of Dunkley Jones et al. (2020). When plotting BAYSPAR SSTs we distinguish samples with BIT indices greater than and less than 0.4, as high BIT can be associated with a small warm bias (Weijers et al., 2006). For the OPTiMAL model we apply its own internal screening criteria that quantifies the extent that fossil GDGT assemblages are non-analogue relative to the modern calibration data, using the Dnearest criteria with a cut-off value of 0.5. All but one pre-NIE GDGT assemblages have Dnearest values that exceed 0.5, whereas eight samples above this level have values less than 0.5.Only OPTiMAL SST data that pass the Dnearest screening criteria are shown.