Description: A fourfold subdivision of the NP10 zonal interval is proposed based on calcareous nannofossil biostratigraphic events associated with lineages in the genus Tribrachiatus. This subdivision, based on a detailed analysis of DSDP Site 550, provides a reliable means of determining relative completeness of upper Paleocene-lower Eocene sections in deep-sea as well as epicontinental settings. By means of calibration to magnetochronology it affords a fine chronologic resolution for Biochron NP10. Correlation of planktonic foraminiferal Zones P5 to P6b to the proposed subzonal scheme as seen in Hole 550 is presented. Carbon isotopic trends in the four NP10 subzones as seen in Hole 550 are also given. The proposed subdivision rests largely upon the range of a new species described herein, Tribrachiatus digitalis. This species has a broad geographic distribution and a restricted range in Zone NP10. The concept of Zone NP10 was recently modified to conform to the proposal that Rhomboaster cuspis and Tribrachiatus bramlettei are synonymous, a view that is not shared here. The structural differences between nannoliths assigned to Rhomboaster and Tribrachiatus are clarified and it is shown that R. cuspis and T. bramlettei are discrete taxa. The main consequence of the new zonal scheme is that it allows the determination of a level equivalent to the base of the London Clay Formation in marine sections outside of northwestern Europe. It is inferred from this that the age of the basal transgression of the London Clay Formation (Walton Member) is 54.37 Ma.

Description: Mn K-edge XANES spectra of KMnO4, MnO2 and MnCO3 standards and Discorhabdus striatus, Watznaueria britannica (four spectra from four different spots within the same coccolith), Discoaster falcatus and Helicosphaera carteri coccoliths. Those data were acquired through the project ES113 at ESRF. D. striatus and W. britannica are from Murtinheira section at Cabo Mondego, Portugal. Discoaster falcatus is from Wilson lake core, NJ, USA. Helicosphaera carteri is from MD05-2920 core section.

Description: The data were generated at ESRF beamline ID22 with an incident energy at 17 keV. Discorhdabus striatus and Watznaueria britannica were analyzed with 0.1 µm x 0.1 µm pixel size and 2 s time analysis per pixel. Both coccoliths were picked from samples from Murtinheira section at Cabo Mondego, Portugal. D. striatus is from sample CM9 and W. britannica from sample CM60 both dated to the lower Bajocian (Middle Jurassic). Sample position in the section in Suchéras-Marx et al. (2012). Data treatment is made using PyMCA. For each calcareous nannofossil, the raw data (.edf in .zip) and the pondered spectrum (.csv) are given. One fit file is given (.cfg) and can be used for both sample. Those data were acquired through the project EC811 at ESRF. Similar results published in Suchéras-Marx et al. (2016).

Description: Changes in the composition of calcareous nannoplankton across the Cretaceous/Paleocene boundary at southern high-latitude Ocean Drilling Program Hole 750A are documented in this semiquantitative study. These changes are compared with changes described from other localities at high- and low-latitudes. This study provides additional data toward a detailed documentation of the paleontologic changes that occurred in the late Maestrichtian and the early Paleocene, despite limitations to the interpretation caused by coring gaps, drilling disturbance, and the presence of an unconformity at the boundary at this site.

Description: A record based on counts of the relative abundance of the dominant calcareous nannofossil taxa Coccolithus pelagicus and Reticulofenestra spp. in sediments recovered from Ocean Drilling Program Hole 747A (Kerguelen Plateau, Southern Indian Ocean) is established in this paper. This record (17 m.y. long) virtually spans the entire Miocene. Broad, steplike variations in the abundance of C. pelagicus range between 0% and 96%. Based on these variations, five stratigraphic units characterized by high abundance in C. pelagicus are delineated. We suggest that these variations are caused by water-mass movements (such as the north/south shifting of a front). This pronounced signal is compared with paleoceanographic events revealed by isotopic (d18O and d13C) studies. The five defined units are tentatively correlated to well-known global isotopic events. In particular, Units A and D correlate respectively with the Oligocene/Miocene boundary glaciation and the middle Miocene cooling event. Time-series analysis indicates the presence of the three main periodic components of the eccentricity of the Earth's orbit. A 200-k.y. cycle is also present. The stratigraphic and paleoceanographic significance of this record is discussed.

Description: An integrated biostratigraphic and stable isotope investigation was conducted on a high-latitude sequence across the Cretaceous/Paleogene (K/P) boundary recovered in Hole 750A in the southern Indian Ocean. The sequence consists of nannofossil chalk and is discontinuous across the boundary; missing is an estimated 0.3-m.y. late Maestrichtian and early Danian interval. Nonetheless, because calcareous nannofossil Zones NP1 and NP2 are well-developed, micropaleontological studies of the sequence have yielded a detailed record of Danian high-latitude microplankton evolution. In addition, stable carbon isotope analyses of planktonic and benthic foraminifer and bulk samples provide a record of late Maestrichtian and early Danian surface- and deep-water carbon isotope variations. Together, the carbon isotope and carbonate accumulation records serve as an index of regional marine net productivity across the boundary. Earliest Danian nannoplankton assemblages consisted mainly of persistent genera that were generally rare or absent in the Upper Cretaceous at Hole 750A. However, by 0.5-0.6 m.y. after the boundary, newly evolving Danian taxa became dominant. The turnover in nannofossil assemblages was accompanied by significant changes in rates of net productivity as gauged by carbon isotope distributions and carbonate accumulation rates. During the period dominated by persistent taxa, net productivity was extremely low, as reflected by the absence of vertical delta13C gradients and reduced carbonate accumulation rates. Later in the Danian, as new species evolved and flourished, vertical delta13C gradients reappeared and carbonate accumulation rates increased, signaling partial recovery of net productivity in this region. The absolute timing and magnitude of late Maestrichtian and early Danian biotic and geochemical changes in the southern Indian Ocean were similar to those recorded in other pelagic K/P boundary sequences from low- and mid-latitude Atlantic and Pacific sites, indicating that these events were ubiquitous.

Description: Calcareous nannofossils are abundant in the Paleogene sediments recovered during Ocean Drilling Program Leg 120. Although no continuous Paleogene section was obtained, Sites 747 through 751 complemented each other so as to provide a virtually complete composite stratigraphic section. The calcareous nannofossil biostratigraphy at Sites 747, 748, and 749 is discussed. Correlation of calcareous nannofossil biozones and magnetozones at these sites suggests some diachrony with low-latitude areas, as well as on a regional basis. Changes in calcareous nannofossil diversity throughout the Paleogene are analyzed and interpreted as reflecting major paleoclimatic events.

Description: Stable carbon and oxygen isotope analyses were conducted on well-preserved planktonic and benthic foraminifers from a continuous middle Eocene to Oligocene sequence at Ocean Drilling Program (ODP) Site 748 on the Kerguelen Plateau. Benthic foraminifer d18O values show a 1.0 per mil increase through the middle and upper Eocene, followed by a rapid 1.2 per mil increase in the lowermost Oligocene (35.5 Ma). Surface-dwelling planktonic foraminifer d18O values increase in the lowermost Oligocene, but only by 0.6 per mil whereas intermediate-depth planktonic foraminifers show an increase of about l.0 per mil. Benthic foraminifer d13C values increase by 0.9 per mil in the lowermost Oligocene at precisely the same time as the large d18O increase, whereas planktonic foraminifer d13C values show little or no change. Site 748 oxygen isotope and paleontological records suggest that southern Indian Ocean surface and intermediate waters underwent significant cooling from the early to late Eocene. The rapid 1.2 per mil oxygen isotope increase recorded by benthic foraminifers just above the Eocene/Oligocene boundary represents the ubiquitous early Oligocene d18O event. The shift here is unique, however, as it coincided with the sudden appearance of ice-rafted debris (IRD), providing the first direct link between Antarctic glacial activity and the earliest Oligocene d18O increase. The d18O increase caused by the ice-volume change in the early Oligocene is constrained by (1) related changes in the planktonic to benthic foraminifer d18O gradient at Site 748 and (2) comparisons of late Eocene and early Oligocene planktonic foraminifer d18Ovalues from various latitudes. Both of these records indicate that 0.3 per mil to 0.4 per mil of the early Oligocene d18O increase was ice-volume related.