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 (∼34 Ma), suggesting a strong relationship between calcium carbonate (CaCO₃) cycling and Antarctic glaciation. However, the linkages between these two events are debated. Here we present new records of bulk sediment stable isotope and carbonate composition from a depth transect of sites in the low-latitude Pacific Ocean and one site from the South Atlantic Ocean, together with a new benthic foraminiferal stable isotope record (δ¹³Cb and δ¹⁸Ob) from the Pacific where the sedimentary sequence is most expanded. Our records reveal a short-lived (∼300 Kyr) CCD shoaling event closely associated with a negative carbon isotope excursion in the latest Eocene. This event is immediately followed by CCD deepening which occurs in two rapid (∼40 Kyr-long) steps. Our data show that the first of these deepening steps represents recovery from the latest Eocene shoaling event while the second was closely associated with a rapid increase in δ¹⁸Ob and shows a distinctive over-deepening and settling pattern to >5 and 4.4 km, respectively. These results, together with good agreement between Pacific and South Atlantic records, strongly suggest that the carbon cycle was perturbed globally shortly before the inception of Antarctic glaciation. Once large-scale Antarctic glaciation was initiated, rapid further change in global seawater chemistry triggered transitory deep ocean carbonate burial fluxes far exceeding their early Oligocene steady state values.

The late Miocene-early Pliocene “biogenic bloom” (BB) manifests as greatly enhanced biogenic sedimentation in sites along the Equator that has been linked to cooler sea surface temperature (SST) in the eastern equatorial Pacific (EEP). However, the full extent and geometry of the BB in the EEP is less known. To improve on this, we have generated new carbonate content (CaCO₃%) and bulk carbonate stable isotope (δ¹³C and δ¹⁸O) records spanning the last 7 Ma at IODP Site U1335, located ca. 5° north of the Equator and to the west of the EEP. Site U1335 δ¹³C and δ¹⁸O records display high-frequency variations coupled to changes in sediment composition and physical properties comparable to patterns seen at on-Equator sites further east. During the late Miocene and the early Pliocene bulk δ¹⁸O is higher at Site U1335 compared to two off-Equator sites further east, suggesting cooler SSTs generated by stronger equatorial upwelling reaching northwest of the modern core-equatorial upwelling belt. Enhanced upwelling at Site U1335 is supported by relatively higher sedimentation rates prior to 4.6 Ma, symptomatic of higher biological production during the BB. These observations suggest that during the BB the equatorial upwelling circulation was more focused and less parallel to the Equator compared to present day. 

This review paper has been thought to emphasize the role of Biostratigraphy in Geosciences and, specifically, of calcareous nannofossils as dating tool. This group of calcareous plankton occurs in Mesozoic and Cenozoic carbonate-bearing marine sediments in all depositional settings and is routinely used for stratigraphic purposes. The importance of calcareous nannofossils in relative dating of marine sediments is due to their abundance, taxonomic diversity, rapid evolution and wide distribution in marine environments. Nannofossil biostratigraphy improved over the last few decades due to the use of accurate methods for data gathering, including acquisition of semiquantitative census data on high-resolution samples. These microfossils contribute to obtain reliable biostratigraphic classification in various time-intervals in the last 66 m.y. and often provide the key to the interpretation of other stratigraphic records. Nannofossil biohorizons can be used as control points for constructing cyclostratigraphic composite sections, and for identification of magnetostratigraphic intervals, and have provided a basis for age models subsequently developed into orbitally tuned cyclostratigraphies or used for chronological revision of polarity timescale.

The base of the Priabonian Stage is one of two stage boundaries in the Paleogene that remains to be formalized. The Alano section (NE Italy) was elected by consensus as a suitable candidate for the base of the Priabonian during the Priabonian Working Group meeting held in Alano di Piave in June 2012. Further detailed research on the section is now followed by a formal proposal, which identifies the base of a prominent crystal tuff layer, the Tiziano bed, at meter 63.57 of the Alano section, as a suitable candidate for the Priabonian Stage. The choice of the Tiziano bed is appropriate from the historical point of view and several bio-magnetostratigraphic events are available to approximate this chronostratigraphic boundary and guarantee a high degree of correlatability over wide geographic areas. Events which approximate the base of the Priabonian Stage in the Alano section are the successive extinction of large acarininids and Morozovelloides (planktonic foraminifera), the Base of common and continuous Cribrocentrum erbae and the Top of Chiasmolithus grandis (nannofossils), as well as the Base of Subchron C17n.2n and the Base of Chron C17n (magnetostratigraphy). Cyclostratigraphic analysis of the Bartonian-Priabonian transition of the Alano section as well as radioisotopic data of the Tiziano tuff layer provide an absolute age (37.710 - 37.762 Ma, respectively) of this bed and, consequently, of the base of the Priabonian Stage.

Poor age control in Pleistocene sediments of the central Arctic Ocean generates considerable uncertainty in paleoceanographic reconstructions. This problem is rooted in the perplexing magnetic polarity patterns recorded in Arctic marine sediments and the paucity of microfossils capable of providing calibrated biostratigraphic biohorizons or continuous oxygen isotope stratigraphies. Here, we document the occurrence of two key species of calcareous nannofossils in a single marine sediment core from the central Arctic Ocean that provide robust, globally calibrated age constraints for sediments younger than 500 ka. The key species are the coccolithophores Pseudoemiliania lacunosa, which went extinct during marine isotope stage (MIS) 12 (478-424 ka), and Emiliania huxleyi, which evolved during MIS 8 (300-243 ka). This is the first time that P lacunosa has been described in sediments of the central Arctic Ocean. The sedimentary horizons containing these age-diagnostic species can be traced, through lithostratigraphic correlation, across more than 450 km of the inner Arctic Ocean. They provide the first unequivocal support for proposed Pleistocene chronologies of sediment from this sector of the Arctic, and they constitute a foundation for developing and testing other geochronological tools for dating Arctic marine sediments.

Drill sites in the southern Bay of Bengal at 3 degrees N 91 degrees E (International Ocean Discovery Program Expedition 362) have sampled for the first time a complete section of the Nicobar Fan and below to the oceanic crust. This generally overlooked part of the Bengal-Nicobar Fan System may provide new insights into uplift and denudation rates of the Himalayas and Tibetan Plateau. The Nicobar Fan comprises sediment gravity-flow deposits, mostly turbidites, that alternate with hemipelagite drapes and pelagite intervals of varying thicknesses. The decimetre-thick to metre-thick oldest pre-fan sediments (limestones/chalks) dated at 69 Ma are overlain by volcanic material and slowly accumulated pelagites (0.5 g cm(-2) kyr(-1)). At Expedition 362 Site U1480, terrigenous input began in the early Miocene at ca 22.5 Ma as muds, overlain by very thin-bedded and thin-bedded muddy turbidites at ca 19.5 Ma. From 9.5 Ma, sand content and sediment supply sharply increase (from 1-5 to 10-50 g cm(-2) kyr(-1)). Despite the abundant normal faulting in the Nicobar Fan compared with the Bengal Fan, it offers a better-preserved and more homogeneous sedimentary record with fewer unconformities. The persistent connection between the two fans ceased at 0.28 Ma when the Nicobar Fan became inactive. The Nicobar Fan is a major sink for Himalaya-derived material. This study presents integrated results of International Ocean Discovery Program Expedition 362 with older Deep Sea Drilling Project/Ocean Drilling Program/International Ocean Discovery Program sites that show that the Bengal-Nicobar Fan System experienced successive large-scale avulsion processes that switched sediment supply between the Bengal Fan (middle Miocene and late Pleistocene) and the Nicobar Fan (late Miocene to early Pleistocene). A quantitative analysis of the submarine channels of the Nicobar Fan is also presented, including their stratigraphic frequency, showing that channel size/area and abundance peaked at ca 2 to 3 Ma, but with a distinct low at 3 to 7 Ma: the intervening stratigraphic unit was a time of reduced sediment accumulation rates.

Stable isotope (delta C-13 and delta O-18) records of bulk marine sediment carry information on past carbon cycling and oceanography, but origins and interpretations remain uncertain because such signals represent mixtures of different biogenic components, each with potential offsets from primary parameters. Studies of Neogene sediment from the eastern equatorial Pacific (EEP) exemplify this issue, because stable isotope records of bulk sediment and foraminifera at different sites exhibit similarities and differences in absolute value that somehow relate to depositional age. Here we measure delta C-13 and delta O-18 of bulk carbonate, two fine-grained fractions (<63 and <20 mu m), mixed-species planktic and benthic foraminifera, and foraminifera fragments from sediments deposited over four time intervals within the last 7 Ma at ODP Site 851. These data are compared to published delta C-13 and delta O-18 records of multiple single-species planktic foraminifera from the same site and benthic foraminifera from an adjacent site. Bulk sediment delta C-13 and delta O-18 records represent a mixed signal dominated by reticulofenestrid coccolith calcite but modified by variable amounts of different foraminifera. Similarities and differences between stable isotope records result from temporal changes in water chemistry and temperature, depths of calcite precipitation, and vital effects that impact fractionation of various biogenic components. The remarkable correlation of bulk stable isotope records within the EEP suggests that several factors change collectively over time across a broad oceanographic region. Ideally, multiple stable isotope records coupled with other proxy measurements might lead to an internally consistent paleoceanographic perspective of the EEP since the late Miocene.

In recent decades, the scientific ocean drilling community has prided itself in being able to achieve the full recovery of hundreds of meters of the sedimentary section through coring, allowing scientists to decipher the history of Earth's climate in its fullest resolution. The Deep Sea Drilling Project, the Ocean Drilling Program, the Integrated Ocean Drilling Program, and the International Ocean Discovery Program provided the impetus for the rapid growth of paleoceanography as a new field of study and contributed significantly to modern-day paleoclimate studies. These new fields are based upon a long progression of technical developments over decades and hundreds of drilling expeditions. Here, we briefly review the technical and coring strategy advances that today allow us to read all the pages in the book on climate history.

The onset of the North Atlantic Deep Water formation is thought to have coincided with Antarctic ice-sheet growth about 34 million years ago (Ma). However, this timing is debated, in part due to questions over the geochemical signature of the ancient Northern Component Water (NCW) formed in the deep North Atlantic. Here we present detailed geochemical records from North Atlantic sediment cores located close to sites of deep-water formation. We find that prior to 36 Ma, the northwestern Atlantic was stratified, with nutrient-rich, low-salinity bottom waters. This restricted basin transitioned into a conduit for NCW that began flowing southwards approximately one million years before the initial Antarctic glaciation. The probable trigger was tectonic adjustments in subarctic seas that enabled an increased exchange across the Greenland-Scotland Ridge. The increasing surface salinity and density strengthened the production of NCW. The late Eocene deep-water mass differed in its carbon isotopic signature from modern values as a result of the leakage of fossil carbon from the Arctic Ocean. Export of this nutrient-laden water provided a transient pulse of CO2 to the Earth system, which perhaps caused short-term warming, whereas the long-term effect of enhanced NCW formation was a greater northward heat transport that cooled Antarctica.

Assemblages of upper lower through upper Miocene Discoaster spp. have been quantified from Integrated Ocean Drilling Program (IODP) Site U1338 in the eastern equatorial Pacific Ocean. These assemblages can be grouped into five broad morphological categories: six-rayed with bifurcated ray tips, six-rayed with large central areas, six-rayed with pointed ray tips, five-rayed with bifurcated ray tips and five-rayed with pointed ray tips. Discoaster deflandrei dominates the assemblages prior to 15.8 Ma. The decline in abundance of D. deflandrei close to the early-middle Miocene boundary occurs together with the evolution of the D. variabilis group, including D. signus and D. exilis. Six-rayed discoasters having large central areas become a prominent member of the assemblages for a 400 ka interval in the late middle Miocene. Five-and six-rayed forms having pointed tips become prominent in the early late Miocene and show a strong antiphasing relationship with the D. variabilis group. Discoaster bellus completely dominates the Discoaster assemblages for a 400 ka interval in the middle late Miocene. Abundances of all discoasters, or discoasters at the species level, show only (surprisingly) weak correlations to carbonate contents or oxygen and carbon isotopes of bulk sediment when calculated over the entire sample interval.