Planktonic foraminifera in the trans-tropical Pacific Ocean

Cores from four Ocean Drilling Program (ODP) sites were examined for planktonic foraminifers. One sample per core (from core-catchers in Holes 806B and 807B and from Section 4 in Holes 847B and 852B) was examined through the interval representing the last 5.8 m.y. Sites 806 (0°19.1'N; 159°21.7'E) and 847 (0o12.1'N; 95°19.2'W) are beneath the equatorial divergence zone. Sites 807 (3°36.4'N; 156°37.5'E) and 852 (5°19.6'N; 110°4.6'W) are located north of the equator in the convergence zone created by the interaction of the westward-flowing South Equatorial Current (SEC) and the eastward-flowing North Equatorial Countercurrent (NECC). Specimens were identified to species and then grouped according to depth habitat and trophic level. Species richness and diversity were also calculated. Tropical neogloboquadrinids have been more abundant in the eastern than in the western equatorial Pacific Ocean throughout the last 5.8 m.y. During the mid-Pliocene (3.8-3.2 Ma), their abundance increased at all sites, while during the Pleistocene (after ~ 1.6 Ma), they expanded in the east and declined in the west. This suggests an increase in surface-water productivity across the Pacific Ocean during the closing of the Central American seaway and an exacerbation of the productivity asymmetry between the eastern and western equatorial regions during the Pleistocene. This faunal evidence agrees with eolian grain-size data (Hovan, 1995) and diatom flux data (Iwai, this volume), which suggest increases in tradewind strength in the eastern equatorial Pacific that centered around 3.5 and 0.5 Ma. The present longitudinal zonation of thermocline dwelling species, a response to the piling of warm surface water in the western equatorial region of the Pacific, seems to have developed after 2.4 Ma, not directly after the closing of the Panama seaway (3.2 Ma). Apparently, after 2.4 Ma, the piling warm water in the west overwhelmed the upwelling of nutrients into the photic zone in that region, creating the Oceanographic asymmetry that exists in the modern tropical Pacific and is reflected in the microfossil record. In the upper Miocene and lower Pliocene sediments, the ratio of thermocline-dwelling species to mixed-layer dwellers is 60%:40%. During the mid-Pliocene, the western sites became 40% thermocline and 60% mixed-layer dwellers. Subsequent to -2.4 Ma, the asymmetry increased to 20%: 80% in the west and the reverse in the east. This documents the gradual thickening of the warm-water layer piled up in the western tropical Pacific over the last 5.8 m.y. and reveals two "steps" in the biotic trend that can be associated with specific events in the physical environment.

Calcium carbonate, biogenic opal, and organic carbon content and d15N ratios of sediments from the Bering Sea

Millennial-scale paleoceanographic changes in the Bering Sea during the last 71 kyrs were reconstructed using geochemical and isotope proxies (biogenic opal, CaCO3, and total organic carbon (TOC), nitrogen and carbon isotopes of sedimentary organic matters) and microfossil (radiolaria and foraminifera) data from two cores (PC23A and PC24A) which were collected from the northern continental slope area at intermediate water depths. Biogenic opal and TOC contents were generally high with high sedimentation rates during the last deglaciation. Laminated sediment depositions during the Early-Holocene (EH) and Bølling-Allerød (BA) were closely related with the increased primary productivity recorded by high biogenic opal and TOC contents and high d15N values. Enhanced surface-water productivity was attributed to increased nutrient supply from strengthened Bering Slope Current (BSC) and from increased amount of glacial melt-water, resulting in high C/N ratios and low d13C values, and high proportion of Rhizoplegma boreale during the last deglaciation. In contrast, low surface-water productivity during the last glacial period was due to depleted nutrient supply caused by strong stratification and to restricted phytoplankton bloom by extensive sea ice distribution under cold climates. Extensive formation of sea ice produces more oxygen-rich intermediate-water, leading to oxic bottom-water conditions due to active ventilation, which favored good preservation of oxic benthic foraminifera species. Remarkable CaCO3 peaks coeval with high biogenic opal and TOC contents in both cores during MIS 3 to MIS 4 are most likely correlated with Dansgaard-Oeschger (D-O) events. High d15N and d13Corg values during D-O interstadials support increased surface-water productivity resulting from nutrients supplied mainly by intensified BSC. During the EH, BA and D-O interstadials, dominant benthic foraminifera species indicate dysoxic bottom-water conditions as a result of increased surface-water productivity and weak ventilation of intermediate-water with mitigated sea ice development caused by strengthening of the Alaskan Stream. It is of note that the bottom-water conditions and formation of intermediate-water in the Bering Sea during the last glacial period are related to the variation of dissolved oxygen concentration of the bottom-water in the northeastern Pacific and to strong ventilation of intermediate-water in the northwestern Pacific. Thus, the millennial-scale paleoceanographic events in the Bering Sea during the D-O interstadials are closely associated with the intermediate-water ventilation, ultimately leading to weakening of North Pacific Intermediate Water.

Bio- and magnetostratigraphic events of ODP holes of the central Kerguelen Plateau

Neogene biostratigraphic and magnetostratigraphic data are compiled from Holes 747A, 748B, and 751A drilled on the Southern Kerguelen Plateau during Ocean Drilling Program Leg 120. Neogene sections have excellent to good magnetostratigraphic signatures in many intervals. This, in addition to minimal coring gaps and the occurrence of mixed assemblages of both calcareous and siliceous microfossil assemblages, makes these valuable biostratigraphic reference sections for intra- and extraregional correlations. This paper combines the sequence of biostratigraphic events reported from diatom, radiolarian, planktonic foraminifer, calcareous nannofossil, and silicoflagellate studies of Leg 120 sediments. It correlates microfossil datums with the geomagnetic polarity time scale to test existing age estimates and to refine biostratigraphic age controls for the southern high latitudes. Significant biostratigraphic datums are presented in a series of age-depth plots. Numerous hiatuses are clearly identified through this approach, and the positions of lesser disconformities are suggested. Most Neogene intervals are represented in at least one site, although "regional" unconformities occur in the upper Pliocene, uppermost Miocene/lowermost Pliocene, middle upper Miocene, middle middle Miocene, and at the lower/middle Miocene boundaries. The longest hiatus spanned 6 m.y., with most other hiatuses representing 1 m.y. or less. This paper compiles Leg 120 biostratigraphic and magnetostratigraphic data for use in future syntheses of southern high latitude biostratigraphy and presents an age model for Leg 120 Neogene sediments.

Oligocene and Neogene radiolarians from the Labrador Sea

Two sites in the Labrador Sea and one site in Baffin Bay were drilled during Leg 105. Radiolarians were recovered at all three sites, although at Site 645 (Baffin Bay), radiolarians were present in useful numbers only in the mudline sample. Radiolarians of late Neogene age were recovered at Site 646 south of Greenland, while early Oligocene and early Miocene radiolarians were recovered from the Labrador Sea at Site 647. In Site 646, radiolarian and other coarse-fraction abundances vary dramatically from sample to sample and may reflect deep-water depositional processes as well as changes in surface-water conditions. Site 647 siliceous microfossils reach their peak abundance and preservation in Core 105-647A-25R and decline gradually upward into the lower Miocene (Cores 105-647A-13R and -14R). Siliceous microfossil abundances in counts of the > 38-µm Carbonate-free coarse fraction from the siliceous interval are correlated to each other, but not to the abundance of nonbiogenic coarse-fraction components. Radiolarian abundances in specimens per gram (but not diatom abundances) are correlated to bulk opal concentration and to the organic carbon content of the sediment. The abundance of radiolarians and other siliceous microfossils within the lower Oligocene to lower Miocene is interpreted as reflecting changes in surface-water productivity. With only a few exceptions, no stratigraphic indicator species were seen in samples from either Site 646 or Site 647. The absence of both tropical/subtropical and Norwegian-Greenland Sea stratigraphic forms is due to the dominance of subarctic North Atlantic taxa in Leg 105 assemblages. The early Oligocene and early Miocene assemblages recovered at Site 647 are of particular interest, as very little material of these ages has previously been recovered from the subarctic North Atlantic region, and virtually no descriptive work has been conducted on the more endemic components of the radiolarian assemblages from these time intervals. Thus, this report concentrates on providing, at least in part, the first comprehensive documentation of early Oligocene and early Miocene radiolarians from the subarctic North Atlantic, with emphasis on basic descriptions, measurements, and photographic documentation. However, synonymic work and formal designation of new species names has been deferred until additional material from other regions can be examined. The sole exception is the emendation of Theocalyptra tetracantha Bjorklund and Kellogg 1972 to Cycladophora tetracantha n. comb.

Physical properties and abundance of diatoms of the ANDRILL AND1-1B drill core

In the austral summer of 2006/7 the ANDRILL MIS (ANtarctic geological DRILLing- McMurdo Ice Shelf) project recovered a 1285 m sediment core from beneath the Ross Ice Shelf near Hut Point Peninsula, Ross Island, Antarctica in a flexural moat associated with the volcanic loading of Ross Island. Contained within the upper ~600 m of this core are sediments recording 38 glacial to interglacial cycles of Early Pliocene to Pleistocene time, including 13 discrete diatomite units (DU). The longest of these, DU XI, is ~76 m thick, contains two distinct unconformities marked by layers of volcanic brecciated sands, and has been assigned an Early to Mid-Pliocene age (5-3 Ma). A detailed record (avg. sample spacing of 33 cm) of the siliceous microfossil assemblages have been generated for DU XI and used in conjunction with geochemical and sedimentological data to subdivide DU XI into four discrete subunits of continuous sedimentation. Within each unit, changes in diatom assemblages have been correlated with the d18O record, providing a temporal resolution as high as 600 yr, and allowing for the construction of a detailed age model and calculation of associated sediment accumulation rates within DU XI. Results indicate a productivity-dominated sedimentary record with higher sediment accumulation rates containing a greater proportion of hemipelagic mud occurring during relatively cool periods and reduced accumulation during warmer intervals. This implies that even during periods of substantial warmth, Milankovitch-paced changes in Antarctic ice volume can be linked to ecological changes recorded as shifts in diatom assemblages.

Stratigraphic occurrence of selected marine palynomorph species recorder in the Paleogene of ODP Hole 105-647A (Table 3)

Dinoflagellate cysts were recovered throughout the Paleogene succession of Hole 647A, which contains an almost complete deep-water record of early Eocene through early late Oligocene sedimentation in the Labrador Sea. Dinoflagellate cyst biostratigraphy is in general accord with that provided by other microfossil groups and is consistent with a lower Eocene age, as determined by nannofossils, for basal sediments in Hole 647A. These sediments overlie oceanic crust of Chron 24 age. Dinocyst assemblages indicate outer neritic to oceanic conditions throughout, although the persistent occurrence of Wetzeliellaceae specimens in the lower Eocene suggests a greater influence from shelf environments during this time. Lower Eocene dinocyst assemblages are similar to coeval assemblages from the Rockall Plateau, but those from the middle to upper Eocene have mixed affinities and may be related to the intensification of the proto-Gulf Stream from middle Eocene time. Oligocene dinocyst assemblages suggest the influence of both arctic and North Atlantic wate rmasses at this site. The presence of protoperidineacean species in the upper Eocene and Oligocene may indicate increased availability of nutrients, perhaps related to increased upwelling or the effects of water-mass mixing. Productive samples are dominated by dinocysts and acritarchs, while sporomorphs are represented mainly by bisaccate pollen. Preservational differences within samples may reflect mixing of penecontemporaneous dinocyst populations during the Eocene, and all samples examined may have a considerable allochthonous component. Variability in relative abundance of many species during the Eocene may be related to fluctuating water-mass properties. A total 175 dinocyst and acritarch taxa were recorded from 53 productive samples from the Paleogene. Only one Paleogene sample was barren of palynomorphs. Of three Miocene samples processed, all were barren.

Stratigraphic first occurrence of Emiliania huxleyi in sediments of the Chatham Rise (Table 2)

A quantitative analysis was carried out of planktonic diatoms (biogenic opal) and calcareous nannofossils (biogenic calcite) in late Quaternary sediments (MIS 1-6) from four cores along a N-S transect east of New Zealand from 39°50'S to 50°04'S across the E-W-trending submarine ridge, the Chatham Rise. This was done to trace movements of oceanic fronts and to improve calcareous nannofossil stratigraphy for the last 130 000 yr in the SW Pacific. Sites ODP 1123 and Q 858 are below present day subtropical surface waters north of Chatham Rise. Site DSDP 594 is below present-day mixed temperate-subantarctic surface water south of the rise, and site ODP 1120 is below subantarctic surface water. The more diverse and opportunistic planktonic diatoms provided marker species for subtropical surface waters (Alveus marina, Fragilariopsis doliolus, Rhizosolenia bergonii and Azpeitia nodulifer) and others for subantarctic surface waters (Nitzschia kerguelensis, Thalassiosira lentiginosa). Application of these tracers permits the following conclusions: (1) subtropical conditions persisted north of Chatham Rise throughout the past 130 000 yr, in spite of the cooling of surface waters during colder periods; (2) during warm times (MIS 5 and MIS 3, and in MIS 1), the sporadic occurrence of subtropical species south of Chatham Rise indicates occasional admixture of subtropical surface waters that far south; (3) subantarctic waters extended to the southern slopes of the Chatham Rise during MIS 5b, late MIS 5a to early MIS 4, during the warmer time intervals in early MIS 3, and during latest MIS 3 to early MIS 2; (4) subantarctic frontal conditions existed over southern Chatham Rise during early MIS 4 and late MIS 3 to early MIS 2; and (5) it is probable that during cooler times, MIS 6, MIS 5b, and in MIS 2, intensified particle transport from the Bounty Trough to the northern flank of Chatham Rise occurred by intensified boundary currents. The larger abundance fluctuations in both microfossil groups at the sites south of Chatham Rise than north of Chatham Rise reflect northward shifts of the Circumpolar Subantarctic Water (CSW) and a contemporaneous disappearance of Australasian Subantarctic Water (ASW), implying an elevated temperature gradient between the surface water masses north and south of the Chatham Rise at the times of such northward shifts of CSW. Calcareous nannofossils are less diverse than diatoms, and are less specialised. Some calcareous nannofossil species show abundance shifts at the same time at different latitudes. Two of these abundance shifts can be used for correlation between subtropical and subantarctic sediments in the SW Pacific: (1) reversal in the relative abundance of Calcidiscus leptoporus and Coccolithus pelagicus associated with the MIS 2/1 boundary; and (2) drop in abundance of Gephyrocapsa muellerae or medium-sized Gephyrocapsa at the MIS 4/3 boundary. An additional abundance shift seems to be restricted to subtropical to mixed temperate-subtropical-subantarctic surface waters: (3) increase in abundance of G. muellerae or medium-sized Gephyrocapsa at the beginning of MIS 2 below the Okareka tephra.

Pollen and non-pollen palynomorph records of the Holocene part of the composite sediment core TMD from lake Tso Moriri (NW India) and of modern surface samples from the Tso Moriri region

The high-altitude lake Tso Moriri (32°55'46'' N, 78°19'24'' E; 4522 m a.s.l.) is situated at the margin of the ISM and westerly influences in the Trans-Himalayan region of Ladakh. Human settlements are rare and domestic and wild animals are concentrating at the alpine meadows. A set of modern surface samples and fossil pollen from deep-water TMD core was evaluated with a focus on indicator types revealing human impact, grazing activities and lake system development during the last ca. 12 cal ka BP. Furthermore, the non-pollen palynomorph (NPP) record, comprising remains of limnic algae and invertebrates as well as fungal spores and charred plant tissue fragments, were examined in order to attest palaeolimnic phases and human impact, respectively. Changes in the early and middle Holocene limnic environment are mainly influenced by regional climatic conditions and glacier-fed meltwater flow in the catchment area. The NPP record indicates low lake productivity with high influx of freshwater between ca. 11.5 and 4.5 cal ka BP which is in agreement with the regional monsoon dynamics and published climate reconstructions. Geomorphologic observations suggest that during this period of enhanced precipitation the lake had a regular outflow and contributed large amounts of water to the Sutlej River, the lower reaches of which were integral part of the Indus Civilization area. The inferred minimum fresh water input and maximum lake productivity between ca. 4.5-1.8 cal ka BP coincides with the reconstruction of greatest aridity and glaciation in the Korzong valley resulting in significantly reduced or even ceased outflow. We suggest that lowered lake levels and river discharge on a larger regional scale may have caused irrigation problems and harvest losses in the Indus valley and lowlands occupied by sedentary agricultural communities. This scenario, in turn, supports the theory that, Mature Harappan urbanism (ca. 4.5-3.9 cal ka BP) emerged in order to facilitate storage, protection, administration, and redistribution of crop yields and secondly, the eventual collapse of the Harappan Culture (ca. 3.5-3 cal ka BP) was promoted by prolonged aridity. There is no clear evidence for human impact around Tso Moriri prior to ca. 3.7 cal ka BP, with a more distinct record since ca. 2.7 cal ka BP. This suggests that the sedimentary record from Tso Moriri primarily archives the regional climate history.

Biomagnetostratigraphy of ODP Leg 189 sites

Late Cretaceous (Maastrichtian)-Quaternary summary biostratigraphies are presented for Ocean Drilling Program (ODP) Leg 189 Sites 1168 (West Tasmanian Margin), 1170 and 1171 (South Tasman Rise), and 1172 (East Tasman Plateau). The age models are calibrated to magnetostratigraphy and integrate both calcareous (planktonic foraminifers and nannofossils) and siliceous (diatoms and radiolarians) microfossil groups with organic walled microfossils (organic walled dinoflagellate cysts, or dinocysts). We also incorporate benthic oxygen isotope stratigraphies into the upper Quaternary parts of the age models for further control. The purpose of this paper is to provide a summary age-depth model for all deep-penetrating sites of Leg 189 incorporating updated shipboard biostratigraphic data with new information obtained during the 3 yr since the cruise. In this respect we provide a report of work to November 2003, not a final synthesis of the biomagnetostratigraphy of Leg 189, yet we present the most complete integrated age model for these sites at this time. Detailed information of the stratigraphy of individual fossil groups, paleomagnetism, and isotope data are presented elsewhere. Ongoing efforts aim toward further integration of age information for Leg 189 sites and will include an attempt to correlate zonation schemes for all the major microfossil groups and detailed correlation between all sites.

Organic matter composition and sulfate reduction intensity in Oman Margin sediments

Petrographical and geochemical studies of Neogene marine sediments from the Oman Sea (Leg 117, Sites 720, 724, 726 and 730), show a close relationship between the nature and amount of the organic matter, and the degree of degradation of organic matter by sulfate reduction, i.e. pyritization. Petrographically, three major pyritization types were observed: (1) Finely dispersed pyrite framboids in sediments from Oman Margin and Indus Fan, enriched in autochthonous marine organic matter. (2) Infilling of pores by massive pyrite crystals in Oman Margin sediments with a low TOC and a high microfossil content. (3) Pyrite mineralization of lignaceous fragments in organic-depleted sediments from the Indus Fan leading to more massive pyrite. Geochemically, we can define a sulfate reduction index (SRI) as the percentage of initial organic carbon versus that of residual organic carbon. Finely laminated Pliocene-Pleistocene sediments from the Oman Margin exclusively contain organic matter deriving from organic phytoplankton, for which the quantity (TOC) positively correlates with the geochemical quality (Hydrogen Index). We think that the occurrence of this residual organic matter is linked mainly to a high primary paleo-productivity. The intensity of sulfate reduction is constant for sediments with TOC up to 2% and becomes more important when organic input decreases. This degradation process can destroy up to 50% of the initial organic matter, but is not sufficient to explain some of the encountered very low TOC values. It can be seen that sharp increases of certain plankton species (with mineral skeletons) are responsible for a pronounced degradation of organic matter, due to increased sulfate reduction. In that case, the organic matter may be strongly degraded (high SRI), although deposited in an oxygen-depleted environment. Conversely, Miocene-Pliocene sediments contain an autochthonous organic matter that is typical of both low productivity and oxic processes; their very low sulfate reduction index indicates that very little metabolizable organic matter was initially present.

Abundance estimates of diatoms in ODP Leg 207 sediments

Twenty-eight core catcher samples were provided to the author by the shipboard party for evaluation of fossil diatoms. Samples are from Ocean Drilling Program Leg 207 Holes 1257A, 1257B, 1257C, and 1258A. The samples range from 50 to 112 meters below the seafloor (mbsf) at Site 1257 and from ~22 to 60 mbsf at Site 1258. At Site 1257, samples range in age from middle Eocene (foraminifer Zone P14-13) to late Paleocene (mid-foraminifer Zone P4). At Site 1258, the samples range from middle Eocene (foraminifer Zone P11) to early Eocene (foraminifer Zone P5) according to the preliminary biostratigraphic reports (Erbacher, Mosher, Malone, et al., 2004, doi:10.2973/odp.proc.ir.207.2004). All samples were processed at Florida State University Antarctic Research Facility. Treatment included acidization and sieving through stacked 38- and 63-µm sieves. Strew slides were made from each fraction and the catcher pan. A Zeiss Photoscope II microscope was used for examination of the prepared slides. Samples from Holes 1257A, 1257B, and 1257C showed that most of the samples are barren of siliceous microfossils. Only a few radiolarians and fragments of radiolarians were observed.

Calculated sea surface temperatures of two sediment cores

The reconstruction of ocean history employs a large variety of methods with origins in the biological, chemical, and physical sciences, and uses modern statistical techniques for the interpretation of extensive and complex data sets. Various sediment properties deliver useful information for reconstructing environmental parameters. Those properties that have a close relationship to environmental parameters are called ''proxy variables'' (''proxies'' for short). Proxies are measurable descriptors for desired (but unobservable) variables. Surface water temperature is probably the most important parameter for describing the conditions of past oceans and is crucial for climate modelling. Proxies for temperature are: abundance of microfossils dwelling in surface waters, oxygen isotope composition of planktic foraminifers, the ratio of magnesium or strontium to calcium in calcareous shells or the ratio of certain organic molecules (e.g. alkenones produced by coccolithophorids). Surface water salinity, which is important in modelling of ocean circulation, is much more difficult to reconstruct. At present there is no established method for a direct determination of this parameter. Measurements associated with the paleochemistry of bottom waters to reconstruct bottom water age and flow are made on benthic foraminifers, ostracodes, and deep-sea corals. Important geochemical tracers are d13C and Cd/Ca ratios. When using benthic foraminifers, knowledge of the sediment depth habitat of species is crucial. Reconstructions of productivity patterns are of great interest because of important links to current patterns, mixing of water masses, wind, the global carbon cycle, and biogeography. Productivity is reflected in the flux of carbon into the sediment. There are a number of fluxes other than those of organic carbon that can be useful in assessing productivity fluctuations. Among others, carbonate and opal flux have been used, as well as particulate barite. Furthermore, microfossil assemblages contain clues to the intensity of production as some species occur preferentially in high-productivity regions while others avoid these. One marker for the fertility of sub-surface waters (that is, nutrient availability) is the carbon isotope ratio within that water (13C/12C, expressed as d13C). Carbon isotope ratios in today's ocean are negatively correlated with nitrate and phosphate contents. Another tracer of phosphate content in ocean waters is the Cd/Ca ratio. The correlation between this ratio and phosphate concentrations is quite well documented. A rather new development to obtain clues on ocean fertility (nitrate utilization) is the analysis of the 15N/14N ratio in organic matter. The fractionation dynamics are analogous to those of carbon isotopes. These various ratios are captured within the organisms growing within the tagged water. A number of reconstructions of the partial pressure of CO2 have been attempted using d13C differences between planktic and benthic foraminifers and d13C values of bulk organic material or individual organic components. To define the carbon system in sea water, two elements of the system have to be known in addition to temperature. These can be any combination of total CO2 , alkalinity, or pH. To reconstruct pH, the boron isotope composition of carbonates has been used. Ba patterns have been used to infer the distribution of alkalinity in past oceans. Information relating to atmospheric circulationand climate is transported to the ocean by wind or rivers, in the form of minerals or as plant andanimal remains. The most useful tracers in this respect are silt-sized particles and pollen.

Integrated Paleocene calcareous plankton magnetobiochronology of DSDP Hole 43-384 in the Northwest Atlantic Ocean

At Deep Sea Drilling Site 384 (J-Anomaly Ridge, Grand Banks Continental Rise, NW Atlantic Ocean) Paleocene nannofossil chalks and oozes (~70 m thick) are unconformably/disconformably underlain (~168 m; upper Maastrichtian) and overlain (~98.7 m; upper lower Eocene) by sediments of comparable lithologies. The chalks are more indurated in stratigraphically higher levels of the Paleocene reflecting increasing amounts of biosiliceous (radiolarians and diatoms) components. This site serves as an excellent location for an integrated calcareous and siliceous microfossil zonal stratigraphy and stable isotope stratigraphy. We report the results of a magnetostratigraphic study which, when incorporated with published magnetostratigraphic results, reveals an essentially complete magnetostratigraphic record spanning the interval from Magnetochron C31n (late Maastrichtian) to C25n (partim) (late Paleocene, Thanetian). Integrated magnetobiochronology and stable isotope stratigraphy support the interpretation of, and constrain the estimated duration of, a short hiatus (~0.9 my) within the younger part of Chron C29r (including the K/P boundary) and an ~6 my hiatus separating upper Paleocene (Magnetozone C25n) and upper lower Eocene (Magnetozone C22r) sediments. Some 30 planktonic foraminiferal datum levels [including the criteria used to denote the Paleocene planktonic foraminiferal (sub)tropical zonal scheme of Berggren and Miller, Micropaleontology 34 (4) (1988) 362-380 and Berggren et al., SEPM Spec. Publ. 54 (1995) 129-212, Geol. Soc. Am. Bull. 107 (11) (1995) 1272-1287], and nearly two dozen calcareous nannoplankton datum levels have been recognized and calibrated to the magnetochronology. Planktonic foraminiferal Subzones P4a and P4b of (upper Paleocene) Zone P4 are emended/redefined based on the discovery of a longer stratigraphic extension of Acarinina subsphaerica (into at last Magnetozone C25n). Stable isotope stratigraphies from benthic foraminifera and fine fraction (<38 µm) carbonate have been calibrated to the biochronology and magnetostratigraphy. A minimum in benthic foraminifer delta13C was reached near the Danian/Selandian boundary (within Chron C26r, planktonic foraminiferal Zone P3a and calcareous nannoplankton Zone NP4) and is followed by the rise to maximum delta13C values in the late Thanetian (near the base of C25n, in Zone P4c and NP9a, respectively) that can be used for global correlation in the Paleocene.