Annotated record of the detailed examination of Mn deposits from DSDP Site 161, Leg 16 (Cores 16-161-1 and 16-161A-14)

DSDP 161 is located on the lower west flank of the East Pacific Rise about midway between the Clipperton and Clarion fracture zones which define the boundaries of a large structural block in the eastern Pacific. The site is about 4,000 km west of the present crest of the Rise. It is located near the northern edge of a zone of thick Cenozoic sediments which marks the general location of the equatorial zone of high biological productivity.

Comparison of nitrogen isotopic values from different preparation methods

We are writing to comment on the work of Tamburini et al. (2003, doi:10.1029/2000PA000616). During the course of subsequent discussions between the authors and ourselves, it has become clear that the published sedimentary nitrogen isotopic values for Ocean Drilling Program (ODP) Site 724 are in error. Our reanalysis of sediment samples from the same intervals has revealed a significant offset from the original d15N data, requiring a revised assessment of their initial interpretation. The purposes of this comment are to (1) address the origin of these errors; (2) outline a protocol for future validation of nitrogen isotopic analyses; and (3) provide revised interpretations of the sedimentary d15N data in terms of the regional relative contributions of denitrification and nitrogen fixation and mean state of the southwest monsoon. (2) Nitrogen isotopic values measured on late Quaternary sediments at Arabian Sea ODP Site 724 by Tamburini et al. (2003, doi:10.1029/2000PA000616) are inexplicably different from a number of published records of d15N from very nearby on the Oman margin (Altabet et al., 1995, doi:10.1038/373506a0; 1999, doi:10.1029/1999PA900035; 2002, doi:10.1038/415159a; Higginson et al., 2004, doi:10.1016/j.gca.2004.03.015) and elsewhere in the Arabian Sea (Reichart et al., 1998, doi:10.1029/98PA02203). These data were generated using similar instrumentation (elemental analyzer coupled with an isotope ratio mass spectrometer) and analytical methodology to those already published. Concerned by this clear discrepancy, we analyzed aliquots of sediment from the same depth intervals for nitrogen abundance and bulk sedimentary nitrogen isotopes. We have been unable to duplicate the values published by Tamburini et al. (2003, doi:10.1029/2000PA000616 ), even after analysis of multiple replicates and due consideration of natural sediment heterogeneities and postrecovery sample storage.

Monthly values of the North Atlantic Oscillation Index from 1821 to 2000

Early instrumental pressure measurements from Gibraltar and the Reykjavik area of Iceland have been used to extend to 1821 the homogeneous pressure series at the two locations. In winter the two sites are located close to the centres of action that comprise the North Atlantic Oscillation (NAO). The extended 'winter half-year' record of the NAO enables recent changes in the record to be placed in the context of the period 1823-1996. The period since the early 1970s is the most prolonged positive phase of the oscillation and the late 1980s and early 1990s is the period with the highest values (strongest westerlies). The winter of 1995-1996 marked a dramatic switch in the index, with the change from 1994-1995 being the greatest change recorded from one year to the next since the series began in 1823. (The extended Gibraltar and Reykjavik monthly pressures and the NAO series can be found on the Climatic Research Unit home page, http://www.cru.uea.ac.uk/).

Accumulation rates of plant-wax-derived long-chain C25 to C35 odd-numbered n-alkanes and d13C values of the n-C31 alkane of ODP Hole 175-1077B

The dominant forcing factors for past large-scale changes in vegetation are widely debated. Changes in the distribution of C4 plants-adapted to warm, dry conditions and low atmospheric CO2 concentrations (Collatz et al., 1998, doi:10.1007/s004420050468) -have been attributed to marked changes in environmental conditions, but the relative impacts of changes in aridity, temperature (Pagani et al., 1999, doi:10.1126/science.285.5429.876; Huang et al., 2001, doi:10.1126/science.1060143) and CO2 concentration (Cerling et al., 1993, doi:10.1038/361344a0; Kuypers et al., 1999, doi:10.1038/20659) are not well understood. Here, we present a record of African C4 plant abundance between 1.2 and 0.45 million years ago, derived from compound-specific carbon isotope analyses of wind-transported terrigenous plant waxes. We find that large-scale changes in African vegetation are linked closely to sea surface temperatures in the tropical Atlantic Ocean. We conclude that, in the mid-Pleistocene, changes in atmospheric moisture content - driven by tropical sea surface temperature changes and the strength of the African monsoon - controlled aridity on the African continent, and hence large-scale vegetation changes.

Annotated record of the detailed examination of Mn deposits from R/V Bosei Maru Cruise GH72-2 stations

In 1972, the five years program 'Basic investigations for exploration of deep sea mineral resources' was laid out by the Agency of Industrial Science and Technology, Ministry of International Trade and Industry. The Geological Survey of Japan and the National Research Institute of Pollution and Resources undertook the first survey project. The survey team consisted of four geologists and a surveyor of the Geological Survey of Japan, and a mechanical, engineer and four mining engineers of National Research Institute of Polution and Resources. The survey started on November 11 using the "Bosei Maru" survey vessel (1100 tons) chartered from Tokai University. The cruise departed from Shimizu harbor to the Ponape and Guam islands, and terminated at the harbor of departure on December 11. The surveyed area was mainly covered the Mariana basin and the Magellan seamounts, and fifteen bottom samples were collected during the cruise. Ferromanganese nodules were obtained at several stations at a depth over 5000m.

Nd and Sm isotopic record from fossil fish teeth recovered from ODP Site 177-1090

Neodymium (Nd) isotopes were measured on 181 samples of fossil fish teeth recovered from Oligocene to Miocene sections at Ocean Drilling Program Site 1090 (3700 m water depth) on Agulhas Ridge in the Atlantic sector of the Southern Ocean. A long-term decreasing trend toward less radiogenic Nd isotope compositions dominates the record. This trend is interrupted by shifts toward more radiogenic compositions near the early/late Oligocene boundary and the Oligocene/Miocene boundary. Overall, epsilon-Nd values at Agulhas Ridge are more radiogenic than at other Atlantic locations, and are similar to those at Indian Ocean locations. The pattern of variability is remarkably similar to Nd isotope results from Walvis Ridge (South Atlantic) and Ninetyeast Ridge (Indian Ocean). In contrast, Agulhas Ridge and Maud Rise Nd isotope records do not show similar patterns over this interval. Results from this study indicate that deep water in the Atlantic flowed predominantly from north to south during the Oligocene and Miocene, and that export of Northern Component Water (NCW) to the Southern Ocean increased in the late Oligocene. There is also evidence for efficient exchange of deep waters between the Atlantic sector of the Southern Ocean and the Indian Ocean, although the direction of deep water flow is not entirely clear from these data. The shifts to more radiogenic Nd isotopic compositions most likely represent increases in the flux of Pacific waters through Drake Passage, and the timing of these events reflect development of a mature Antarctic Circumpolar Current (ACC). The relative timing of increased NCW export and ACC maturation support hypotheses that link deep water formation in the North Atlantic to the opening of Drake Passage.

FTIR-inferred biogeochemical properties for the past 3.6 Myr in the sediment record of core ICDP5011-1 in Lake Elgygytgyn, NE Russia

A number of studies have shown that Fourier transform infrared spectroscopy (FTIR) can be applied to quantitatively assess lacustrine sediment constituents. In this study, we developed calibration models based on FTIR for the quantitative determination of biogenic silica (BSi; n = 420; gradient: 0.9-56.5%), total organic carbon (TOC; n = 309; gradient: 0-2.9%), and total inorganic carbon (TIC; n= 152; gradient: 0-0.4%) in a 318 m-long sediment record with a basal age of 3.6 million years from Lake El'gygytgyn, Far East Russian Arctic. The developed partial least squares (PLS) regression models yield high cross-validated (CV) R2CV = 0.86-0.91 and low root mean square error of cross-validation (RMSECV) (3.1-7.0% of the gradient for the different properties). By applying these models to 6771 samples from the entire sediment record, we obtained detailed insight into bioproductivity variations in Lake El'gygytgyn throughout the middle to late Pliocene and Quaternary. High accumulation rates of BSi indicate a productivity maximum during the middle Pliocene (3.6-3.3 Ma), followed by gradually decreasing rates during the late Pliocene and Quaternary. The average BSi accumulation during the middle Pliocene was ~3 times higher than maximum accumulation rates during the past 1.5 million years. The indicated progressive deterioration of environmental and climatic conditions in the Siberian Arctic starting at ca. 3.3 Ma is consistent with the first occurrence of glacial periods and the finally complete establishment of glacial-interglacial cycles during the Quaternary.

Annotated record of the detailed examination of Mn deposits from various ship expeditions in the Atlantic Ocean from 1876 until 1911

The greater part of this Monograph is devoted to detailed descriptions of 1426 samples of deposits from the floor of the Atlantic Ocean stored in the Challenger Office, Edinburgh, which had been collected during thirty-five cruising expeditions between 1857 and 1911. The remaining part discusses the results of the work. The work of examining and describing in detail this abundant mass of material was in progress when the late Sir JOHN MURRAY met his death in March 1914. By that time about three-fourths of the descriptive work had been completed under his supervision. Sir John's trustees arranged for the completion of the descriptive work by Mr Chumley, and this was done in the Challenger Office during the two succeeding years. Later, after he had removed to Glasgow, Mr Chumley prepared the notes discussing the results. The trustees have pleasure in recording, on the suggestion of Mr Chumley, the courtesy of Dr G. W. Lee of the Geological Survey of Scotland, for help in determining many of the rarer mineral particles contained in the deposits.

(Table 1) N-isotope record of planktonc foraminifera of sediment core MD02-2550C2

Constraining variations in marine N2-fixation over glacial-interglacial timescales is crucial for determining the role of the marine nitrogen cycle in modifying ocean productivity and climate, yet paleo-records from N2-fixation regions are sparse. Here we present new nitrogen isotope (d15N) records of bulk sediment and foraminifera test-bound (FB) nitrogen extending back to the last ice age from the oligotrophic Gulf of Mexico (GOM). Previous studies indicate a substantial terrestrial input during the last ice age and early deglacial, for which we attempt to correct the bulk sediment d15N using its observed relationship with the C/N ratio. Both corrected bulk and FB-d15N reveal a substantial glacial-to-Holocene decrease of d15N toward Holocene values of around 2.5 per mil, similar to observations from the Caribbean. This d15N change is most likely due to a glacial-to-Holocene increase in regional N2-fixation. A deglacial peak in the FB-d15N of thermocline dwelling foraminifera Orbulina universa probably reflects a whole ocean increase in the d15N of nitrate during deglaciation. The d15N of the surface dwelling foraminifera Globigerinoides ruber and the corrected bulk d15N show little sign of this deglacial peak, both decreasing from last glacial values much earlier than does the d15N of O. universa; this may indicate that G. ruber and bulk N reflect the euphotic zone signal of an early local increase in N2-fixation. Our results add to the evidence that, during the last ice age, the larger iron input from dust did not lead to enhanced N2-fixation in this region. Rather, the glacial-to-Holocene decrease in d15N is best explained by a response of N2-fixation within the Atlantic to the deglacial increase in global ocean denitrification.

(Appendix) Petrographic record from excavation profiles in Old-Luebeck (Liubice), north Germany

Die Frage einer Küstensenkung spielt seit Jahrzehnten bei der geologischen Erforschung des norddeutschen und niederländischen Flachlandes eine große Rolle. Der Schwerpunkt der bisherigen Arbeiten lag im südlichen Nordseeraum. Gerade dieses Gebiet bereitet aber wegen seines Aufbaues aus jungen, teilweise stark setzungsfähigen Gesteinen, des von Ort zu Ort und im Laufe der Zeit unterschiedlichen Einflusses der Gezeiten sowie wegen mancher anderer Bedingungen sehr große methodische Schwierigkeiten. Deshalb überrascht es nicht, daß die einzelnen Untersuchungen noch in den letzten beiden Jahrzehnten für die verschiedenen Abschnitte zu sehr abweichenden Folgerungen kamen, so daß die heute bekannten Einzeltatsachen nur ein recht widerspruchsvolles Gesamtbild ergeben. Da eine Klärung der Probleme durch eine Neubearbeitung an der Nordsee zunächst wenig erfolgversprechend erscheint, wird die Aufmerksamkeit unvermeidlich auf die Verhältnisse im südwestlichen Ostseeraum gelenkt. Hier bestehen in mancher Hinsicht einfachere Bedingungen, die eine derartige Untersuchung begünstigen. Vor allem die Nachbarschaft des skandinavischen Hebungsgebietes am gleichen Wasserbecken, die sehr geringen Gezeitenwirkungen und die hier weit verbreiteten Sandschüttungen bieten bessere Vergleichsmöglichkeiten und schalten viele Fehlerquellen aus. In der voliegenden Arbeit wurden die litorinazeitlichen und die nachlitorinazeitlichen Vertikalbewegungen des Landes und die eustatischen Schwankungen des Wasserstandes im südwestlichen Ostseeraum mit geologisch-morphologischen Methoden und durch die Auswertung von Lage und Verbreitung ur- und frühgeschichtlicher Funde sowie unter Auswertung von pollenanalytisch datierten Bohrprofilen und Pegelaufzeichnungen untersucht.

Geochemical analyses and Delta47 values in shallow water corals

Geochemical variations in shallow water corals provide a valuable archive of paleoclimatic information. However, biological effects can complicate the interpretation of these proxies, forcing their application to rely on empirical calibrations. Carbonate clumped isotope thermometry (Delta47) is a novel paleotemperature proxy based on the temperature dependent "clumping" of 13C-18O bonds. Similar ?47-temperature relationships in inorganically precipitated calcite and a suite of biogenic carbonates provide evidence that carbonate clumped isotope variability may record absolute temperature without a biological influence. However, large departures from expected values in the winter growth of a hermatypic coral provided early evidence for possible Delta47 vital effects. Here, we present the first systematic survey of Delta47 in shallow water corals. Sub-annual Red Sea Delta47 in two Porites corals shows a temperature dependence similar to inorganic precipitation experiments, but with a systematic offset toward higher Delta47 values that consistently underestimate temperature by ~8 °C. Additional analyses of Porites, Siderastrea, Astrangia and Caryophyllia corals argue against a number of potential mechanisms as the leading cause for this apparent Delta47 vital effect including: salinity, organic matter contamination, alteration during sampling, the presence or absence of symbionts, and interlaboratory differences in analytical protocols. However, intra- and inter-coral comparisons suggest that the deviation from expected Delta47 increases with calcification rate. Theoretical calculations suggest this apparent link with calcification rate is inconsistent with pH-dependent changes in dissolved inorganic carbon speciation and with kinetic effects associated with CO2 diffusion into the calcifying space. However, the link with calcification rate may be related to fractionation during the hydration/hydroxylation of CO2 within the calcifying space. Although the vital effects we describe will complicate the interpretation of Delta47 as a paleothermometer in shallow water corals, it may still be a valuable paleoclimate proxy, particularly when applied as part of a multi-proxy approach.

Stable isotope record of planktonic foraminifera of sediment core TR163-19

Stable isotope data from eastern equatorial Pacific (EEP) core TR163-19 (2°15'N, 90°57'W, 2348 m) are presented for the surface-dwelling foraminifers Globigerinoides ruber and G. sacculifer and thermocline-dwelling Globorotalia menardii and Neogloboquadrina dutertrei. Using species-specific normalization factors derived from experimental and plankton tow data, we reconstruct a 360 kyr record of water column hydrography across the past three glacial cycles. We demonstrate that G. ruber maintains a mixed layer habitat throughout the entire record, while G. sacculifer records a mixture of thermocline and mixed layer conditions and G. menardii and N. dutertrei record thermocline properties. We conclude that G. sacculifer is not appropriate for paleoceanographic applications in regions with steep vertical hydrographic gradients. Results suggest that this region of the EEP had a thicker mixed layer and deeper d13CDIC boundary between the surface and equatorial undercurrent during the last two glacial periods. A shift in N. dutertrei and G. sacculifer geochemistry prior to ~185 kyr suggests water column structure and chemocline gradients changed, possibly due to a shift in the position of the undercurrent relative to this site. The timing and magnitude of glacial-interglacial d13C variations between species indicates that near-surface carbon chemistry is controlled by changes in productivity, atmospheric circulation, and advected intermediate water sources north of the Antarctic polar front. These results demonstrate that when properly calibrated for species differences, multispecies geochemical data sets can be invaluable for reconstructing water column structure and properties in the past.

Pollen data and pollen-based climate reconstruction for the KTK1 pollen record from Lake Kotokel

In this study a radiocarbon-dated pollen record from Lake Kotokel (52°47' N, 108°07' E, 458 m a.s.l.) located in southern Siberia east of Lake Baikal was used to derive quantitative characteristics of regional vegetation and climate from about 15 kyr BP (1 kyr = 1000 cal. yr) until today. Quantitative reconstruction of the late glacial vegetation and climate dynamics suggests that open steppe and tundra communities predominated in the study area prior to ca. 13.5 kyr BP and again during the Younger Dryas interval, between 12.8 and 11.6 kyr BP. The pollen-based climate reconstruction suggests lower-than-present mean January (~ -38 °C) and July (~ 12 °C) temperatures and annual precipitation (~ 270-300 mm) values during these time intervals. Boreal woodland replaced the primarily open landscape around Kotokel three times at about 14.8-14.7 kyr BP, during the Allerød Interstadial between 13.3-12.8 kyr BP and with the onset of the Holocene interglacial between 11.5 and 10.5 kyr BP, presumably in response to a noticeable increase in precipitation, and in July and January temperatures. The maximal spread of the boreal forest (taiga) communities in the region is associated with a warmer and wetter-than-present climate (Tw ~ 17-18 °C, Tc ~ -19 °C, Pann ~ 500-550 mm) that occurred ca. 10.8-7.3 kyr BP. During this time interval woody vegetation covered more than 50 % of the area within a 21x21 km window around the lake. The pollen-based best modern analogue reconstruction suggests a decrease in woody cover percentages and in all climatic variables about 7-6.5 kyr BP. Our results demonstrate a gradual decrease in precipitation and mean January temperature towards their present-day values in the region around Lake Kotokel since that time.