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 (δ18Ocalite, δ13Ccalcite) as well as Mg/Ca ratios from living planktonic foraminifera to in-situ physical and chemical water mass properties (temperature, salinity, δ18Oseawater, δ13CDIC). Our analyses point to Globigerinoides ruber as the shallowest dweller, followed by Globigerinoides sacculifer, Neogloboquadrina dutertrei, Pulleniatina obliquiloculata and Globorotaloides hexagonus inhabiting increasing 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 ~95mand ~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 δ13C 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: 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: 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.

Description: The Aktau succession is located at 44.03°N and 79.30°E in the Ili Basin, south-east Kazakhstan. The dataset contains measurement results from the Middle to early Late Miocene part of the succession (total height: 372 m, lowermost sample: 0.29 m, uppermost sample: 370.94 m). Stable carbon and oxygen istopes and CaSO₄ content were derived from bulk rock measurements. The CaSO₄ content was determined by microwave digestions and ICP-OES analysis. The laser ablation U-Pb data was aquired from thin sections in order to obtain radiometric ages of carbonates along the Aktau succession.

Description: The Aktau succession is located at 44.03°N and 79.30°E in the Ili Basin, south-east Kazakhstan. The dataset contains measurement results from the Middle to early Late Miocene part of the succession (total height: 372 m, lowermost sample: 0.29 m, uppermost sample: 370.94 m). Stable carbon and oxygen istopes were derived from bulk rock measurements.

Description: The Aktau succession is located at 44.03°N and 79.30°E in the Ili Basin, south-east Kazakhstan. The dataset contains measurement results from the Middle to early Late Miocene part of the succession (total height: 372 m, lowermost sample: 0.29 m, uppermost sample: 370.94 m). CaSO₄ content were derived from bulk rock measurements. The CaSO₄ content was determined by microwave digestions and ICP-OES analysis.

Description: The Aktau succession is located at 44.03°N and 79.30°E in the Ili Basin, south-east Kazakhstan. The dataset contains measurement results from the Middle to early Late Miocene part of the succession (total height: 372 m, lowermost sample: 0.29 m, uppermost sample: 370.94 m). The laser ablation U-Pb data was aquired from thin sections in order to obtain radiometric ages of carbonates along the Aktau succession.