Foraminiferal isotope ratios from IODP Site U1313

Large-amplitude millennial-scale climate oscillations have been identified in late Pleistocene climate archives from around the world. These oscillations appear to be of larger amplitude during times of enlarged ice sheets. This observation suggests the existence of a relationship between large-amplitude millennial variations in climate and extreme glacial conditions and therefore that the emergence of millennial-scale climate variability may be linked to the Pliocene intensification of northern hemisphere glaciation (iNHG). Here we test this hypothesis using new late Pliocene high-resolution (ab. 400 year) records of ice-rafted debris deposition and stable isotopes in planktic foraminiferal calcite (Globigerinoides ruber) generated from Integrated Ocean Drilling Program Site U1313 in the subpolar North Atlantic (a reoccupation of the classic Deep Sea Drilling Project Site 607). Our records span marine oxygen isotope stages (MIS) 103-95 (ab. 2600 to 2400 ka), the first interval during iNHG (ab. 3.5 to 2.5 Ma) in which large-amplitude glacial-interglacial cycles and inferred sea level changes occur. Our records reveal small-amplitude variability at periodicities of ab. 1.8 to 6.2 kyr that prevails regardless of (inter)glacial state with no significant amplification during the glacials MIS 100, 98, and 96. These findings imply that the threshold for the amplification of such variability to the proportions seen in the marine archive of the last glacial was not crossed during the late Pliocene and, in view of all available data, likely not until the Mid-Pleistocene Transition.

Paleoclimatate of the Middle Burdigalian-Langhian period in Turkey

The Miocene is the last warm episode in Earth history, and this episode was well recorded in Turkey as shown by plant distribution and inferred numerical temperature values. In this study, Ören-Kultak, Hüssamlar and Karacaagac palynofloras from western Turkey, which are characterized by the thermophilous plants (Engelhardia, Sapotaceae, Cyrillaceae, Avicennia, Arecaceae, Palmae), are described. Age determinations of these palynofloras (middle Burdigalian-Langhian) are strengthened by the mammalian fossil record (MN4-5) and strontium isotope results. Palaeoclimate is humid and warm subtropical during the middle Burdigalian-Langhian time interval in Europe and Turkey. However, temperature difference has been observed between Europe and Turkey during this time interval and it could be explained by the palaeogeographic position of countries. Despite some discrepancies in the climatic values and palaeovegetation groups, warm climatic conditions are recorded, based on the palynofloras, in Turkey (Cayyrhan, Havza, Can, Etili, Gönen, Bigadic, Emet, Kirka and Kestelek, Sabuncubeli, Soma, Tire, Kulogullary, Bascayyr, Hüssamlar and Karacaagac), Greece and elsewhere in Europe throughout the middle Burdigalian-Langhian period. This warming is related to the Middle Miocene Climatic Optimum period. Carbon and oxygen isotope values obtained from tooth enamel of Gomphotherium sp. from Kultak and Hüssamlar indicate similar ecological condition during the Burdigalian-Langhian time. This isotopic result and high MAPDRY value from the Kultak locality are in agreement with ecological interpretation of mammalian fossils. Besides, according to the precipitation values, central and northwestern Anatolian sites provide more rainfall during the Burdigalian-Langhian time interval than the western Anatolian sites.

Relative abundances of twenty-eight dominant benthic foraminifera species of DSDP Hole 23-219 (Table 1s)

Tropical climate is variable on astronomical time scale, driving changes in surface and deep-sea fauna during the Pliocene-Pleistocene. To understand these changes in the tropical Indian Ocean over the past 2.36 Myr, we quantitatively analyzed deep-sea benthic foraminifera and selected planktic foraminifera from >125 µm size fraction from Deep Sea Drilling Project Site 219. The data from Site 219 was combined with published foraminiferal and isotope data from Site 214, eastern Indian Ocean to determine the nature of changes. Factor and cluster analyses of the 28 highest-ranked species distinguished four biofacies, characterizing distinct deep-sea environmental settings. These biofacies have been named after their most dominant species such as Stilostomella lepidula-Pleurostomella alternans (Sl-Pa), Nuttallides umbonifer-Globocassidulina subglobosa (Nu-Gs), Oridorsalis umbonatus-Gavelinopsis lobatulus (Ou-Gl) and Epistominella exigua-Uvigerina hispido-costata (Ee-Uh) biofacies. Biofacies Sl-Pa ranges from ~2.36 to 0.55 Myr, biofacies Nu-Gs ranges from ~1.9 to 0.65 Myr, biofacies Ou-Gl ranges from ~1 to 0.35 Myr and biofacies Ee-Uh ranges from 1.1 to 0.25 Myr. The proxy record indicates fluctuating tropical environmental conditions such as oxygenation, surface productivity and organic food supply. These changes appear to have been driven by changes in monsoonal wind intensity related to glacial-interglacial cycles. A shift at ~1.2-0.9 Myr is observed in both the faunal and isotope records at Site 219, indicating a major increase in monsoon-induced productivity. This coincides with increased amplitude of glacial cycles, which appear to have influenced low latitude monsoonal climate as well as deep-sea conditions in the tropical Indian Ocean.

Palynological analyses of the sediments around the Miocene/Pliocene boundary in ODP Hole 151-911A

The late Neogene evolution of the Arctic to Subarctic region is poorly understood due to few available records and poor age control. At the margin of the Arctic Ocean, Yermak Plateau Ocean Drilling Program (ODP) Hole 911A is strategically located for establishing a stratigraphic framework for the Arctic. Here we present dinoflagellate cyst and acritarch data from 24 stratigraphic levels in the lower part (474.26-505.64 metres below the seafloor (mbsf)) of ODP Hole 911A. The marine palynomorphs indicate a latest Miocene to earliest Pliocene age (between 5.8 and 5.0 Ma) for the base of the hole based on the co-occurrence of the dinoflagellate cyst Barssidinium evangelineae and acritarch Lavradosphaera crista. Our age estimate for the sediments can possibly be further refined to 5.0-5.33 Ma based on the presence of Achomosphaera andalousiensis suttonensis, which apparently has a range restricted to the Pliocene. An age close to the Miocene/Pliocene boundary agrees with the planktonic foraminifer data. Together with recently available magnetostratigraphic data, the base of the hole is likely to be placed at ~5.2 Ma. This new chronostratigraphy is a first step towards a better understanding of the late Neogene palaeoenvironment for the Yermak Plateau and also for the wider Arctic to Subarctic region. The terrestrial and fresh water palynomorphs were most likely redistributed and/or displaced from the shelf towards deeper parts of the basin during contourite deposition under the influence of the West Spitsbergen Current. The in situ marine dinoflagellate cyst assemblage contains a mixture of cool water and thermophilic taxa, indicating sea-ice free, cool-temperate, warmer than present conditions at the Yermak Plateau. Rivers were likely the source for the freshwater influence.

(Appendix B) Benthic foraminifera in Indian Ocean surface sediments

Multivariate analysis was performed on percentages of 46 species of unstained deep-sea benthic foraminifera from 131 core-top to near-core-top samples (322-5013 m) from across the Indian Ocean. Faunal data are combined with GEOSECS geochemical data to investigate any relationship between benthic foraminifera (assemblages and species) and deep-sea properties. In general, benthic foraminifera show a good correlation to surface productivity, organic carbon flux to the sea floor, deep-sea oxygenation and, to a lesser extent, to bottom temperature, without correlation with the water depths. The foraminiferal census data combined with geochemical data has enabled the division of the Indian Ocean into two faunal provinces. Province A occupies the northwestern Indian Ocean (Arabian Sea region) where surface primary production has a major maximum during the summer monsoon season and a secondary maximum during winter monsoon season that leads to high organic flux to the seafloor, making the deep-sea one of the most oxygen-deficient regions in the world ocean, with a pronounced oxygen minimum zone (OMZ). This province is dominated by benthic foraminifera characteristic of low oxygen and high organic food flux including Uvigerina peregrina, Robulus nicobarensis, Bolivinita pseudopunctata, Bolivinita sp., Bulimina aculeata, Bulimina alazanensis, Ehrenbergina carinata and Cassidulina carinata. Province B covers southern, southeastern and eastern parts of the Indian Ocean and is dominated by Nuttallides umbonifera, Epistominella exigua, Globocassidulina subglobosa, Uvigerina proboscidea, Cibicides wuellerstorfi, Cassidulina laevigata, Pullenia bulloides, Pullenia osloensis, Pyrgo murrhina, Oridorsalis umbonatus, Gyroidinoides (= Gyroidina) soldanii and Gyroidinoides cf. gemma suggesting well-oxygenated, cold deep water with low (oligotrophic) and pulsed food supply.