Description: Insight into past changes of upper ocean stratification, circulation, and nutrient signatures rely on our knowledge of the apparent calcification depth (ACD) and ecology of planktonic foraminifera, which serve as archives for paleoceanographic relevant geochemical signals. The ACD of different species varies strongly between ocean basins, but also regionally. We constrained foraminiferal ACDs in the western Pacific warm pool (Manihiki Plateau) by comparing stable oxygen and carbon isotopes (d18Ocalcite, d13Ccalcite) as well as Mg/Ca ratios from living planktonic foraminifera to in-situ physical and chemical water mass properties (temperature, salinity, d18Oseawater, d13CDIC). Our analyses point to Globigerinoides ruber as the shallowest dweller, followed by Globigerinoides sacculifer, Neogloboquadrina dutertrei, Pulleniatina obliquiloculata and Globotaloides hexagonus inhabiting increasingly greater depths. These findings are consistent with other ocean basins; however, absolute ACDs differ from other studies. The uppermost mixed-layer species G. ruber and G. sacculifer denote mean calcification depths of ~95 m and ~120 m, respectively. These Western Pacific ACDs are much deeper than in most other studies and most likely relate to the thick surface mixed layer and the deep chlorophyll maximum in this region. Our results indicate that N. dutertrei appears to be influenced by mixing waters from the Pacific equatorial divergence, while P. obliquiloculata with an ACD of ~160 m is more suitable for thermocline reconstructions. ACDs of G. hexagonus reveal a deep calcification depth of ~450 m in oxygen-depleted, but nutrient-rich water masses, consistent to other studies. As the d13C of G. hexagonus is in near-equilibrium with ambient seawater, we suggest this species is suitable for tracing nutrient conditions in equatorial water masses originating in extra-topical regions.

Description: The internal development of the tropicalWest Pacific Warm Pool and its interaction with high latitude ocean regions on geological timescales is only poorly constrained. Based on two newly recovered sediment cores fromthe southeastern margin of the West Pacific Warm Pool (northern and southern Manihiki Plateau), we provide new aspects on the dynamically interacting ocean circulation at surface, subsurface, thermocline, and deep thermocline levels during the Pleistocene (~2.5-0.5 Ma). Notably, the variability of thermocline and deep thermocline(~150-400 m water depth) foraminiferal Mg/Ca-based temperatures with up to ~6 °C amplitude variations exceeds those at shallower depths (down to ~120 m) with only ~2-3 °C temperature variations. A major gradual reorganization of the West Pacific Warm Pool oceanography occurred during the transitional timeperiod of ~1.7-1.35 Ma. Prior to ~1.7 Ma, pronounced meridional and latitudinal gradients in sea-surface to subsurface ocean properties point to the eastward displacement of the West Pacific Warm Pool boundaries, with the South Pacific Convergence Zone being shifted further northeastward across Manihiki Plateau. Simultaneously, the low amplitude variations of thermocline and deep thermocline temperatures refer to an overall deep and stable thermocline. The meridional and zonal gradients in sea-surface and subsurface ocean propertieswithin the West Pacific Warm Pool reveal a pronounced change after 1.5 Ma, leading to a more southward position of the warm South Pacific Convergence Zone between ~1.35-0.9 Ma and ~0.75-0.5 Ma. Synchronous to the changes in the upper ocean, the deeper water masses experienced high amplitude variations in temperature, most prominently since ~1.5 Ma. This and the dynamically changing thermocline were most likely associated to the impact of southern- sourced mode waters, which might have developed coincidently with the emergence of the East Pacific Cold Tongue and high latitude sea-surface cooling.

Description: This data set contains results of analyses performed on core M125-34-2 (retrieved during R/V METEOR Expeditin M125 in Spring 2016) from the cold water coral-bearing Bowie Mound, located off Cabo Frio, Eastern Brazil. Analyses were performed to determine the paleoenvironmental conditions that favored or prevented coral growth. The data comprises cold water coral contents and bioturbation index based on CT-scanning, benthic foraminiferal isotopes (C and O), 13C of organic material, sortable silt, elemental ratios based on XRF core-scanning, mineral content based on Rietveld refinement of XRD data, as well as bulk TOC content and Corganic/Ntotal ratios. For comparison an off-mound site (M125-50-3) was analyzed for benthic foraminiferal isotopes (C and O) and sortable silt.

Description: The present datasets include multispecies foraminiferal geochemical data (δ¹⁸O, δ¹³C, Mg/Ca), which was used to make seawater temperature and δ¹⁸O sw reconstructions for the Maldives Inner Sea across the Marine Isotope Stages (MISs) 1-2 and 10-13. All data comes from International Ocean Discovery Program (IODP) Site 359-U1467 samples. All data, other less otherwise indicated in the tables below, is new data generated in this study.

Description: Due to their large heat and moisture storage capabilities, the tropics are fundamental in modulating both regional and global climate. Furthermore, their thermal response during past extreme warming periods, such as super interglacials, is not fully resolved. In this regard, we present high-resolution (analytical) foraminiferal geochemical (δ^18^O and Mg/Ca) records for the last 1800 kyr from the shallow (487 m) Inner Sea drift deposits of the Maldives archipelago in the equatorial Indian Ocean. Considering the diagenetic susceptibility of these proxies, in carbonate-rich environments, we assess the integrity of a suite of commonly used planktonic and benthic foraminifera geochemical datasets (Globigerinoides ruber (white), Globigerinita glutinata (with bulla), Pulleniatina obliquiloculata (with cortex) and Cibicides mabahethi) and their use for future paleoceanographic reconstructions. Using a combination of spot Secondary Ion Mass Spectrometer, Electron Probe Micro-Analyzer and Scanning Electron Microscope image data, it is evident that authigenic overgrowths are present on both the external and internal test (shell) surfaces, yet the degree down-core as well as the associated bias is shown to be variable across the investigated species and proxies. Given the elevated authigenic overgrowth Mg/Ca (∼12–22 mmol/mol) and δ^18^O values (closer to the benthic isotopic compositions) the whole-test planktonic G. ruber (w) geochemical records are notably impacted beyond ∼627.4 ka (24.7 mcd). Yet, considering the setting (i.e. bottom water location) for overgrowth formation, the benthic foraminifera δ^18^O record is markedly less impacted with only minor diagenetic bias beyond ∼790.0 ka (28.7 mcd). Even though only the top of the G. ruber (w) and C. mabahethi records (whole-test data) would be suitable for paleo-reconstructions of absolute values (i.e. sea surface temperature, salinity, seawater δ^18^O), the long-term cycles, while dampened, appear to be preserved. Furthermore, planktonic species with thicker-tests (i.e. P. obliquiloculata (w/c)) might be better suited, in comparison to thinner-test counter-parts (i.e. G. glutinata (w/b), G. ruber (w)), for traditional whole-test geochemical studies in shallow, carbonate-rich environments. A thicker test equates to a smaller overall bias from the authigenic overgrowth. Overall, if the diagenetic impact is constrained, as done in this study, these types of diagenetically altered geochemical records can still significantly contribute to studies relating to past tropical seawater temperatures, latitudinal scale ocean current shifts and South Asian Monsoon dynamics.

Description: The complex deglacial to Holocene oceanographic development in the Gulf of Guayaquil (Eastern Equatorial Pacific) is reconstructed for sea surface and subsurface ocean levels from (isotope) geochemical proxies based on marine sediment cores. At sea surface, southern sourced Cold Coastal Water and tropical Equatorial Surface Water/Tropical Surface Water are intimately related. In particular since ~10 ka, independent sea surface temperature proxies capturing different seasons emphasize the growing seasonal contrast in the Gulf of Guayaquil, which is in contrast to ocean areas further offshore. Cold Coastal Water became rapidly present in the Gulf of Guayaquil during the austral winter season in line with the strengthening of the Southeast Trades, while coastal upwelling off Peru gradually intensified and expanded northward in response to a seasonally changing atmospheric circulation pattern affecting the core locations intensively since 4 ka BP. Equatorial Surface Water, instead, was displaced and Tropical Surface Water moved northward together with the Equatorial Front. At subsurface, the presence of Equatorial Under Current-sourced Equatorial Subsurface Water was continuously growing, prominently since ~10-8 ka B.P. During Heinrich Stadial 1 and large parts of the Bølling/Allerød, and similarly during short Holocene time intervals at ~5.1-4 ka B.P. and ~1.5-0.5 ka B.P., the admixture of Equatorial Subsurface Water was reduced in response to both short-term weakening of Equatorial Under Current strength from the northwest and emplacement by tropical Equatorial Surface Water, considerably warming the uppermost ocean layers.