Nicholas J Shackleton's research while affiliated with University of Alberta and other places
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Publications (154)
BOREAS Kellogg, T. B., Duplessy, J. C. & Shackleton, N. J. 1978 03 01: Planktonic foraminiferal and oxygen isotopic stratigraphy and paleoclimatology of Norwegian Sea deep-sea cores. Boreas. Vol. 7, pp. 61–73. Oslo. ISSN 0300–9483.Three Norwegian Sea deep-sea cores, which penetrate to sediments at least 200,000 years old, were analyzed for oxygen i...
Centennial climate variability over the last ice age exhibits clear bipolar behavior. High-resolution analyses of marine sediment
cores from the Iberian margin trace a number of associated changes simultaneously. Proxies of sea surface temperature and
water mass distribution, as well as relative biomarker content, demonstrate that this typical nort...
A 13-million-year continuous record of Oligocene climate from the equatorial Pacific reveals a pronounced "heartbeat" in the global carbon cycle and periodicity of glaciations. This heartbeat consists of 405,000-, 127,000-, and 96,000-year eccentricity cycles and 1.2-million-year obliquity cycles in periodically recurring glacial and carbon cycle e...
Centennial climate variability over the last ice age exhibits clear bipolar behavior. High-resolution analyses of marine sediment cores from the Iberian margin trace a number of associated changes simultaneously. Proxies of sea surface temperature and water mass distribution, as well as relative biomarker content, demonstrate that this typical nort...
The marine isotopic stage 3 (MIS3) at Ocean Drilling Program (ODP) Site 1060 (Gulf Stream) shows both sharp onset and end of interstadials, the existence of very short lived warm events during stadials, and points to differences in detail between the sea surface temperature (SST) record from the western North Atlantic and the atmospheric temperatur...
Records of planktonic and benthic foraminiferal δ18O and planktonic Mg/Ca from core TR163-22, just northwest of the Galápagos Islands, reveal a detailed (250–450 year resolution) climate history of the region over the last 135 thousand years (kyr). Sea surface temperatures (SSTs), reconstructed from G. ruber Mg/Ca, averaged 24.3±0.4 °C during the H...
The marine isotopic stage 3 (MIS3) at Ocean Drilling Program (ODP) Site 1060 (Gulf Stream) shows both sharp onset and end of interstadials, the existence of very short lived warm events during stadials, and points to differences in detail between the sea surface temperature (SST) record from the western North Atlantic and the atmospheric temperatur...
A 13-million-year continuous record of Oligocene climate from the equatorial Pacific reveals a pronounced "heartbeat" in the global carbon cycle and periodicity of glaciations. This heartbeat consists of 405,000-, 127,000-, and 96,000-year eccentricity cycles and 1.2-million-year obliquity cycles in periodically recurring glacial and carbon cycle e...
Similar orbital geometry and greenhouse gas concentrations during marine isotope stage 11 (MIS 11) and the Holocene make stage 11 perhaps the best geological analogue period for the natural development of the present interglacial climate. Results of a detailed study of core MD01-2443 from the Iberian margin suggest that sea surface conditions durin...
Here we present results from ODP Core Site 1240 (Leg 202, 0 ° 01.31'N, 86° 27.76'W, 2921 mbsl) located in the Eastern Equatorial Pacific (EEP), under the northern edge of the so-called "Cold Tongue". This frontal system separates the cold, salty waters of the Peru Current from warmer and fresher tropical waters of the Northern Hemisphere. This stud...
The mid-Pliocene was an interval of subtle reorganisation within the nannoplankton community, including the prominent and biostratigraphically important last occurrences of Sphenolithus abies and Reticulofenestra pseudoumbilicus. The transition is part of the Pliocene to Recent ‘attrition’ of nannofossil species that resulted from changes in the di...
The mid-Pliocene was an interval of subtle reorganisation within the nannoplankton community, including the prominent and biostratigraphically important last occurrences of Sphenolithus abies and Reticulofenestra pseudoumbilicus. The transition is part of the Pliocene to Recent "attrition" of nannofossil species that resulted from changes in the di...
Pollen and oceanographic data from deep ocean core MD95-2039 provide a centennial to millennial scale record of conditions offshore and of the vegetation of north-west Iberia for the period 10-65 ka. The planktonic oxygen isotope record of this core, reflecting predominantly sea surface temperature (SST), shows a pattern of millennial-scale oscilla...
Recent hypothesis consider low latitudes as the source region for past global rapid climatic changes. In this sense, the Eastern Equatorial Pacific (EEP) is an area with great potential to trigger global changes due to its active role in the El Niño-Southern Oscillation (ENSO). Here we present results obtained from ODP 1240 (Leg 202, 0° 01.31'N, 86...
The correlation of Earth's orbital parameters with climatic variations has been used to generate astronomically calibrated geologic time scales of high accuracy. However, because of the chaotic behavior of the solar system, two initially close calculations of Earth's orbit diverge exponentially and have a large uncertainty beyond several million ye...
Fossil nannoplankton assemblages are controlled by both initial plankton production and dissolution throughout the water column and on the seafloor. It is usually assumed that dissolution can be identified by subjective visual assessment of preservation state. We have tested this by a quantitative comparison of mid-Pliocene nannofossil assemblages...
We present a detailed study of menardellid speciation, abundance and coiling changes between 6.34 and 5.1 Ma (latest Miocene and earliest Pliocene). Menardellids are widely distributed in tropical to subtropical waters from Miocene to modern time, revealing a stable isotopic signature characteristic for the top of the thermocline and shallower rath...
We present a detailed study of menardellid speciation, abundance and coiling changes between 6.34 and 5.1 Ma (latest Miocene and earliest Pliocene). Menardellids are widely distributed in tropical to subtropical waters from Miocene to modern time, revealing a stable isotopic signature characteristic for the top of the thermocline and shallower rath...
Downcore cyclic variation in high-resolution nannofossil abundance records from mid-Pliocene equatorial Atlantic ODP Sites 662 and 926 demonstrate the direct response by several Pliocene taxa (notably Discoaster, Sphenolithus and Florisphaera profunda) to orbitally forced climatic variation. In particular, these records display strong obliquity and...
We have studied Ocean Drilling Program Site 1060 on the Blake Outer Ridge, which lies beneath the Gulf Stream. We focus on marine isotope stage 3, 60-25 thousand years before present (ka). Sea surface temperatures (SSTs) inferred both from foraminiferal fauna and alkenone ratios, as well as counts of iceberg melt-out debris and benthic stable isoto...
At Ocean Drilling Program (ODP) Site 1090 (subantarctic South Atlantic), benthic foraminiferal stable isotope data (from Cibicidoides and Oridorsalis) span the late Oligocene through early Miocene (~24-16 Ma) at a temporal resolution of ~5 ky. Over the same interval, a magnetic polarity stratigraphy can be unequivocally correlated to the geomagneti...
Core MD 98-2165 (9° 38'96 S, 118° 20'31 E, 2100 m) from the tropical Indian Ocean has been studied at a time resolution of about 200 y over the two last climatic cycles within the POP project. Oxygen and carbon isotopic composition (delta 18O and delta 13C) of benthic and planktonic foraminifera has been measured. The benthic d18O record is remarka...
[1] Oxygen and carbon isotope records are important tools used to reconstruct past ocean and climate conditions, with those of benthic foraminifera providing information on the deep oceans. Reconstructions are complicated by interspecies isotopic offsets that result from microhabitat preferences (carbonate precipitation in isotopically distinct env...
Detailed study of associations of planktonic foraminifera in cores MD95-2043 and ODP 977, located in the Alboran Sea (Mediterranean Sea), has allowed the identification of 29 new faunal events, defined by abrupt changes in the abundances of Neogloboquadrina pachyderma (right and left coiling), Turborotalita quinqueloba, Globorotalia scitula, Globor...
Abrupt and intensive sea surface temperature changes (SST; measured from C37 alkenones) have been identified in core ODP977 situated in the Alboran Sea (36^o1.907'N 1^o57.319'W; average sedimentation 22 cm/kyr for MIS1-4 and 14 cm/kyr for MIS5-7). The changes between MIS1-3 parallel those already observed in a previous Alboran core MD952043 (Cacho...
The subdivision of Marine Isotope Stage 5 (MIS5) into five substages is robustly applicable to benthic oxygen isotope records from almost all areas of the ocean. The association of the Eemian Interglacial (in the sense that this concept is utilized by palynologists) with MIS 5e is widely agreed on the basis of a diversity of evidence. Here we prese...
High-resolution palaeoclimate records recovered from the Iberian margin in core MD95-2040 exhibit large fluctuations in oceanographic conditions over the last 190 ka. Large-scale cooling of the surface ocean is indicated by the presence of the polar planktonic foraminifer Neogloboquadrina pachyderma (sinistral), and in some instances the occurrence...
Two geochemical methods (Mg/Ca ratios and delta18O) have been combined to reconstruct changes in the water properties of the Alboran Sea (Westernmost basin of the Mediterranean Sea) in response to the rapid climatic variability of the last glacial period and last deglaciation. The high sedimentation rates of the studied sediment core (MD 95-2043) p...
Detailed study of associations of planktonic foraminifera in cores MD95-2043 and ODP 977, located in the Alboran Sea (Mediterranean Sea), has allowed the identification of 29 new faunal events,defined by abrupt changes in the abundances of Neogloboquadrina pachyderma (right and left coiling), Turborotalita quinqueloba, Globorotalia scitula, Globoro...
Oxygen and carbon isotope records are important tools used to reconstruct past ocean and climate conditions, with those of benthic foraminifera providing information on the deep oceans. Reconstructions are complicated by interspecies isotopic offsets that result from microhabitat preferences (carbonate precipitation in isotopically distinct environ...
High-resolution palaeoclimate records recovered from the Iberian margin in core MD95-2040 exhibit large fluctuations in oceanographic conditions over the last 190 ka. Large-scale cooling of the surface ocean is indicated by the presence of the polar planktonic foraminifer Neogloboquadrina pachyderma (sinistral), and in some instances the occurrence...
Model studies suggest that the formation rate of deep-water in the Nordic seas and regional air temperatures are tightly linked via modulation of the meridional transport of ocean heat. Yet, paleoceanographic reconstructions, which rely on geochemical proxies, have yet to definitively resolve the precise relationship between past changes in meridio...
[1] A multiproxy paleoceanographic record from the Atlantic margin off the British Isles reveals in unprecedented detail discharges of icebergs and meltwater in response to sea surface temperature increases across the last deglaciation. We observe the earliest signal of deglaciation as a moderate elevation of sea surface temperatures that commenced...
We agree with Zachos and colleagues that much can be learned about
transient climate events from well-dated carbonate sediments from the
deep ocean, and that the problem of recrystallization of such sediments
(when tens of millions of years old) means that constraining relative
temperature changes from oxygen-isotope data is more appropriate than
a...
The last interglacial, commonly understood as an interval with climate as warm or warmer than today, is represented by marine isotope stage (MIS) 5e, which is a proxy record of low global ice volume and high sea level. It is arbitrarily dated to begin at approximately 130,000 yr B.P. and end at 116,000 yr B.P. with the onset of the early glacial un...
Since its identification nearly fifty years ago, Marine Iso-tope Stage 5 (MIS 5) has been placed onto absolute time scales on the basis of three independent approaches. Cesare Emiliani, who set up the isotope stages (Emiliani, 1955), depended on uranium-series dating of the sediments, a method that today is regarded as not generally capable of yiel...
We have generated benthic foraminiferal Mg/Ca records from eastern tropical Atlantic core M16772 (3.9 km) and eastern tropical Pacific core TR163-31P (3.2 km) to assess the potential for using benthic Mg-paleothermometry to reconstruct Quaternary bottom water temperature histories. Variations in Mg/Ca records from both the Atlantic and Pacific show...
The reference list of this article was not reproduced correctly during the production process (issue numbers were used as volume numbers). The correct list is given below [1-35]. The publishers would like to apologize for any inconvenience caused by this error.
The Holocene is characterized by its stable climate in the context of
the last 500 kyr (McManus et al., Science, 1999). In spite of this
stability short and long term changes have been identified (Grootes and
Stuiver, J. Geophys. Res., 1997; Bond et al., Science, 1997; Dahl-Jensen
et al., Science, 1998). Stable isotope and pollen records in contine...
We use an X-ray fluorescence (XRF) Core Scanner to obtain records of elemental concentrations in sediment cores from Ocean Drilling Program (ODP) Leg 171B, Site 1052 (Blake Nose, Atlantic margin of northern Florida).This record spans the Middle to Late Eocene, as indicated by bio- and magnetostratigraphy, and displays cyclicity that can be attribut...
Rapid climate shifts in the glacial North Atlantic have been linked to the impact of meltwater discharges on thermohaline circulation but the mechanisms of ice sheet/ocean coupling are poorly constrained at the present level of resolution. Of fundamental importance is what triggered the massive iceberg fluxes that repeatedly perturbed the glacial c...
Paleoceanographic-paleoclimatic records of the Western Mediterranean Sea (IMAGES-MD 95-2043) have previously documented the strong sensitivity of the area to the millennial scale variability of the last glacial period. These studies have also provided a good stratigraphic tool (based on a high resolution alkenone-SST profile) to link records to the...
Climate models with increased levels of carbon dioxide predict that global warming causes heating in the tropics, but investigations of ancient climates based on palaeodata have generally indicated cool tropical temperatures during supposed greenhouse episodes. For example, in the Late Cretaceous and Eocene epochs there is abundant geological evide...
The production of cold, deep waters in the Southern Ocean is an important factor in the Earth's heat budget. The supply of deep water to the Pacific Ocean is presently dominated by a single source, the deep western boundary current east of New Zealand. Here we use sediment records deposited under the influence of this deep western boundary current...
A deep-sea sediment core from the western Portuguese margin has provided a continuous, high-resolution record of millennial-scale climatic oscillations during the interval 9000–65,000 yr B.P. Pollen analysis of the same sequence allows direct, in situ assessment of the phase relationship between the North Atlantic climate system and vegetation chan...
Spectral analyses of an uninterrupted 5.5-million-year (My)-long chronology of late Oligocene-early Miocene climate and ocean carbon chemistry from two deep-sea cores recovered in the western equatorial Atlantic reveal variance concentrated at all Milankovitch frequencies. Exceptional spectral power in climate is recorded at the 406-thousand-year (...
This work presents a detailed, orbitally tuned biogenic silica record of continental paleoclimate change during the Brunhes chron. The Brunhes/Matuyama boundary lies within the warm isotopic stage 19 in Baikal, and the boundaries between eight lithological cycles correspond to terminations in the marine oxygen isotope record. The high amplitude and...
A deep-sea sediment core from the western Portuguese margin has provided a continuous, high-resolution record of millennial-scale climatic oscillations during the interval 9000-65,000 yr B.P. Pollen analysis of the same sequence allows direct, in situ assessment of the phase relationship between the North Atlantic climate system and vegetation chan...
We use an X-ray fluorescence (XRF) Core Scanner to obtain records of elemental concentrations in sediment cores from Ocean Drilling Program (ODP) Leg 171B, Site 1052 (Blake Nose, Atlantic margin of northern Florida).This record spans the Middle to Late Eocene, as indicated by bio- and magnetostratigraphy, and displays cyclicity that can be attribut...
Sea surface temperature (SST) profiles over the last 25 kyr derived from alkenone measurements are studied in four cores from a W-E latitudinal transect encompassing the Gulf of Cadiz (Atlantic Ocean), the Alboran Sea, and the southern Tyrrhenian Sea (western Mediterranean). The results document the sensitivity of the Mediterranean region to the sh...
A core recovered on the Iberian margin off southern Portugal can be correlated with Greenland ice cores using oxygen isotope variability in planktonic foraminifera which closely matches the ice core records of temperature over Greenland. Our age model identifies the base of every interstadial between 64,000 and 24,000 years ago and uses the Greenla...
We develop a new method, based on interference patterns between the precession and obliquity components of geological data from Ocean Drilling Program (ODP) Leg 154 and astronomical solutions, to extract small changes in the precession constant p due to tidal dissipation over the last 25 million years and to put numerical constraints on the paramet...
The deep-sea sediment oxygen isotopic composition (delta(18)O) record is dominated by a 100,000-year cyclicity that is universally interpreted as the main ice-age rhythm. Here, the ice volume component of this delta(18)O signal was extracted by using the record of delta(18)O in atmospheric oxygen trapped in Antarctic ice at Vostok, precisely orbita...
The stratotype section for the base of the Miocene is at a reversed
(below) to normal (above) magnetic transition that is claimed to
represent magnetic chron C6Cn.2n (o). Deep Sea Drilling Project (DSDP)
Site 522 is the only location we are aware of that unambiguously records
the three normal events of C6Cn. We have quantitatively determined the
ra...
Sea surface temperature and salinity estimates reconstructed using planktonic foraminiferal abundance and δ18O records from core SU90-03 (40°N, 32°W, 2475 m water depth) reveal large climatic fluctuations linked to major instabilities in Northern Hemisphere ice sheets over the last 150 000 years. Episodes of enhanced ice rafted detritus (IRD) input...
A core recovered on the Iberian margin off southern Portugal can be correlated with Greenland ice cores using oxygen isotope variability in planktonic foraminifera which closely matches the ice core records of temperature over Greenland. Our age model identifies the base of every interstadial between 64,000 and 24,000 years ago and uses the Greenla...
The stratotype section for the base of the Miocene is at a reversed (below) to normal (above) magnetic transition that is claimed to represent magnetic chron C6Cn.2n (o). Deep Sea Drilling Project (DSDP) Site 522 is the only location we are aware of that unambiguously records the three normal events of C6Cn. We have quantitatively determined the ra...
The interplay between evolution, paleoecology, and environmental change is examined in a geochemical study of a group of Eocene planktonic foraminifera. The hantkeninids, which are well-known biostratigraphic inde × fossils, underwent spectacular long-term evolution in the middle and upper Eocene (49.0 33.7 Ma), a time when major global climate and...
Sea surface temperature and salinity estimates reconstructed using planktonic foraminiferal abundance and delta18O records from core SU90-03 (40°N, 32°W, 2475 m water depth) reveal large climatic fluctuations linked to major instabilities in Northern Hemisphere ice sheets over the last 150 000 years. Episodes of enhanced ice rafted detritus (IRD) i...
Multiproxy data from North Atlantic deep-sea sediment core NEAP18K
provide a detailed record of climate through oxygen isotope stage (OIS)
5. Seven distinct, large-scale episodes of ice rafting (C25 C19) were
identified between 126 and 70 ka. Global ice-volume reconstructions,
based on high-resolution benthic δ18O records, indicate
that major ice-r...
Past sea surface temperature (SST) evolution in the Alboran Sea (western Mediterranean) during the last 50,000 years has been inferred from the study of C37 alkenones in International Marine Global Change Studies MD952043 core. This record has a time resolution of ~200 years allowing the study of millennial-scale and even shorter climatic changes....
We present a Sr chemostratigraphic reference section for the late middle to late Miocene (14-5 Ma) from Ocean Drilling Program site 926 on the Ceara Rise. This site combines a precise, orbitally tuned timescale with a high sedimentation rate (15 m/m.y.), continuous deposition, and excellent biostratigraphic control. The Sr isotope curve is based on...
The first direct evidence that the deep flow speed of North Atlantic Deep Water (NADW) in the South Iceland and North American Basins declined dramatically over a period of a few hundred years at about 120,000 years ago is presented. The flow rate inferred from silt grain-size then rose into the subsequent cool period (stage 5d). These changes are...
Durante la crociera BS 79 del CNR svoltasi nel 1979 sono state prelevate due carote a gravità, la BS 79-33 e la BS 79-38, nel Bacino di Cefalù, nel Mar Tirreno meridionale. Sulle carote si sono svolte analisi qualitative e quantitative su foraminiferi bentonici e planctonici e analisi isotopiche dell’ossigeno e del carbonio. Tali studi multidiscipl...
During the CNR cruise BS 79 performed in 1979, two gravity cores, BS 79-33 and BS 79-38, were recovered in the Cefalù Basin, in the southern part of the Tyrrhenian Sea. Qualitative and quantitative investigations on benthic and planktonic foraminifera, oxygen and carbon stable isotope measurements have been carried out on the cores. This multidisci...
A Minolta CM-2022 spectrophotometer has been used to characterize
downcore fluctuations in sediment lightness and color in core NEAP15K, a
7-m core collected from the northeast Atlantic Ocean. High-resolution
data series, measured using a 4-mm-diameter measurement spot and a 1-cm
sampling interval, were generated along two independent tracks down t...
Surface water and deep ocean palaeoclimate records obtained from North Atlantic core SU90-03 (40°N, 32°W) exhibit pronounced fluctuations at sub-orbital time scales. Surface temperature variability in the mid-latitude Atlantic over the last 150 kyr is dominated by forcing at precession (21 kyr) and semi-precession harmonics (11 kyr). Abrupt changes...
During ODP Leg 171B, devoted to the analysis of the Blake Plateau margin in front of Florida, 16 holes have been drilled in 5 distinct sites. The sites have documented a sedimentary succession ranging in age from Aptian to Eocene. Emphasis has been put on critical periods, comprising the Paleocene-Eocene transition, the Cretaceous-Tertiary boundary...
Au cours de la campagne ODP 171 B, consacrée à l'analyse de la marge du Blake Plateau au large de la Floride, 16 forages ont été effectués. Répartis en cinq sites principaux, ils ont permis d'établir une colonne sédimentaire allant de l'Aptien à l'Éocène. L'accent a été mis sur une succession de périodes critiques comprenant la transition Paléocène...
We have developed a detailed time scale for the late Miocene and later middle Miocene by correlating lithologic cyclicity observed at Site 926 to the astronomically determined variations in northern hemisphere summer insolation. Most of the equiv-alent section at Site 925 can be correlated in the same manner. The validity of the phase relationship...
In the late Paleocene to early Eocene, deep sea benthic foraminifera suffered their only global extinction of the last 75 million years and diversity decreased worldwide by 30-50% in a few thousand years. At Maud Rise (Weddell Sea, Antarctica; Sites 689 and 690, palaeodepths 1100 m and 1900 m) and Walvis Ridge (Southeastern Atlantic, Sites 525 and...
Two techniques for estimating past variations in sea surface temperature (SST) have been used to investigate climatic change in Biogeochemical Oceanic Flux Study (BOFS) core 31K (19°N, 20°W) from the eastern subtropical Atlantic. High-resolution SST records for the last 28 kyr have been produced using planktonic foraminiferal assemblages, based on...
In the late Paleocene to early Eocene, deep sea benthic foraminifera suffered global extinction and diversity worldwide by 30-50% in a few thousand years. At Maud Rise and Walvis Ridge post-extinction faunas were low-diversity and high-dominance, but the dominant species differed by geographical location. This suggests different post-extinction sea...
The δ13C and Cd data are consistent and show that the northeast Atlantic Ocean was strongly stratified with 13C enriched, low Cd intermediate water overlying 13C depleted, high Cd deep water. The glacial water column comprised two different water masses: deep water, similar in character to present Antarctic Bottom Water (AABW), and intermediate wat...
Oxygen and carbon isotope ratios were measured in benthic foraminifers from the entire Pliocene and latest Miocene sections of Site 846, a 180-m section, at a sampling interval of 10 cm. This provides a temporal resolution of about 2500 yr. The documented continuity of the record is excellent. Using the time scale that was developed on the basis of...
Present-day low-latitude eastern and western Atlantic basins are geochemically distinct below the sill depth of the Mid-Atlantic Ridge. While Antarctic Bottom Water (AABW) circulates freely in the western Atlantic, flow into the eastern Atlantic is restricted below 4 km which results in filling the abyssal depths of this basin with water of geochem...
The delta13C and Cd measurements from benthic foraminifera from Biogeochemical Ocean Flux Study (BOFS) northeast Atlantic Ocean sediment cores are presented. The delta13C values in glacial foraminifera are consistent with those from elsewhere in the North Atlantic Ocean. For intermediate water (1000 - 2000 m water depth), delta13C values were highe...
The sediments recovered during Leg 138 provide a remarkable opportunity to improve the geological time scale of the late Neogene. We have developed new time scales in the following steps. First, we constructed age models on the basis of shipboard magnetostratigraphy and biostratigraphy, using the time scale of Berggren, Kent, and Flynn (1985). Seco...
We construct age models for a suite of cores from the northeast Atlantic Ocean by means of accelerator mass spectrometer dating of a key core, BOFS 5K, and correlation with the rest of the suite. The effects of bioturbation and foraminiferal species abundance gradients upon the age record are modeled using a simple equation. The degree of bioturbat...
Several hundred samples of bulk sediments from all the 11 sites drilled during Ocean Drilling Program (ODP) Leg 138 in the eastern equatorial Pacific Ocean have been analyzed for d13C and d18O. The d13C records provide information on the changes in the operation of the global carbon cycle during the late Neogene that were postulated by Shackleton (...
The molecular stratigraphy of Biogeochemical Oceanic Flux Study core 31K (19°N, 20°10'W) and Ocean Drilling Program Hole 658C (20°45'N, 18°35'W) has been studied for C37 alkenone abundances over the past 80 ka at high resolution (~circa 200-500 years). The derived Uk 37' sea surface temperature record for both cores shows a range of temperatures fr...
A stable-isotope stratigraphy at Site 846 (tropical Pacific, 3°06'S, 90°49'W, 3307 m water depth), based on the benthic foraminifers Cibicides wuellerstorfi and Uvigerina peregrina, yields a high-resolution record of deep-sea delta18O and delta13C over the past 1.8 Ma, with an average sampling interval of 3 k.y. Variance in the delta18O and delta13...
The sediments recovered during Leg 138 have provided us with a remarkable opportunity to improve the stratigraphic framework for east-central Pacific Ocean Neogene age sediments. In this chapter, we review some of the data that have been generated and derive best estimates for the ages of potentially useful biostratigraphic datums, within the paleo...
Marine sediments from 3°37′S, 83°58′W yield a well-dated pollen record of equatorial Andean vegetation. Moderate development of Podocarpus -high montane rainforest (∼34,000-28,000 yr B.P.) and increase of high Andean grassland pollen (∼28,000-16,000 yr B.P.) imply an extended dry, cool glacial period following a brief interstade. Rapid stepwise exp...
Below oxygen isotope stage 16, the orbitally derived time-scale developed by Shackleton et al. [1] from ODP site 677 in the equatorial Pacific differs significantly from previous ones [e.g., 2–5], yielding estimated ages for the last Earth magnetic reversals that are 5–7% older than the values [6–8] but are in good agreement with recent dating [9–1...
A record of relative paleointensity from marine sediments in the equatorial Indian Ocean spanning the last 4 Ma completes a previous dataset from Ocean Drilling Program (ODP) Leg 138 sites in the equatorial Pacific [1]. The timescale was defined with a precision better than 20 kyr with different and independent methods. Most of the features present...
High-resolution benthic oxygen isotope and dust flux records from Ocean Drilling Program site 659 have been analyzed to extend the astronomically calibrated isotope timescale for the Atlantic from 2.85 Ma back to 5 Ma. Spectral analysis of the delta18O records indicates that the 41-kyr period of Earth's orbital obliquity dominates the Pliocene reco...
High-resolution benthic oxygen isotope and dust flux records from Ocean Drilling Program site 659 have been analyzed to extend the astronomically calibrated isotope timescale for the Atlantic from 2.85 Ma back to 5 Ma. Spectral a