Influence of the water content on X‐ray fluorescence core‐scanning measurements in soft marine sediments

Tjallingii, Rik; Röhl, Ursula; Kölling, Martin; Bickert, Torsten

doi:10.1029/2006gc001393

Cited by 381 publications

(362 citation statements)

References 30 publications

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“…Similar variations have been previously described in sediment cores to indicate substantial analytical deviations due to physical sedimentary properties (i.e. Tjallingii and Röhl et al, 2007;Hennekam and de Lange 2012). Accordingly, for this study we have concentrated our interpretations on Al, Si and K 235 values from the XRF analyses in discrete samples (see below).…”

supporting

confidence: 64%

Late Oligocene obliquity-paced contourite sedimentation in the Wilkes Land margin of East Antarctica: implications for paleoceanographic and ice sheet configurations

Salabarnada

Escutia

Röhl

et al. 2017

Preprint

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The late Oligocene experienced atmospheric concentrations of CO 2 between 400 and 750 ppm, which are within the IPCC projections for this century, assuming unabated CO 2 emissions. However, Antarctic Unlike today, the continental shelf was not over-deepened, and thus marine-based ice sheet expansion was likely limited to coastal regions. Combined, these data suggest that ice sheets in the Wilkes 60 Subglacial Basin were largely land-based, and therefore retreated as a consequence of surface melt during late Oligocene, rather than direct ocean forcing and marine ice sheet instability processes as it did in younger past warm intervals. Spectral analysis on late Oligocene sediments from the eastern Wilkes Land margin show that the glacial-interglacial cyclicity and resulting displacements of the Southern Ocean frontal systems between 26-25 Ma were forced by obliquity. 65Clim. Past Discuss., https://doi

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supporting

confidence: 64%

Late Oligocene obliquity-paced contourite sedimentation in the Wilkes Land margin of East Antarctica: implications for paleoceanographic and ice sheet configurations

Salabarnada

Escutia

Röhl

et al. 2017

Preprint

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“…The element intensities provided by XRF core scanning represent the counts rates of each individual element after integration of the measurement time. Element intensities measured on dry powder material are primarily related to element concentrations (Tjallingii et al, 2007). However, matrix absorption-and enhancement-effects might potentially bias element intensity data, whereas log-ratios of element intensities are linearly related to log-ratios of element concentrations (Weltje and Tjallingii, 2008).…”

Section: -Ray Fluorescence (Xrf) Core-scanning and Statistical Analmentioning

confidence: 99%

“…The inorganic composition of the sediments was analyzed using a Avaatech XRF core scanner (Tjallingii et al, 2007), which uses energy-dispersive fluorescence radiation to measure composition as element intensities in counts s -1 in a non-destructive way. Loosely packed samples were prepared by pressing ca.…”

Section: -Ray Fluorescence (Xrf) Core-scanning and Statistical Analmentioning

confidence: 99%

Differential degradation of intact polar and core glycerol dialkyl glycerol tetraether lipids upon post-depositional oxidation

Lengger

Kraaij

Tjallingii

et al. 2013

Organic Geochemistry

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Archaeal and bacterial glycerol dialkyl glycerol tetraether lipids (GDGTs) are used in various proxies, such as TEX 86 and the BIT index. In living cells, GDGTs contain polar head groups (intact polar lipids -IPLs). IPL GDGTs have also been detected in ancient marine sediments and it is unclear whether or not they are fossil entities or are part of living cells. In order to determine the extent of degradation of IPL GDGTs over geological timescales, we analyzed turbidite deposits, which had been partly reoxidized for several kyr after deposition on the Madeira Abyssal Plain. Analysis of core lipid (CL) and IPL-derived GDGTs showed a reduction in concentration by two orders of magnitude upon post-depositional oxidation, while IPL GDGTs with a mono-or dihexose head group decreased by 2-3 orders of magnitude. The BIT index for CL-and IPL-derived GDGTs increased substantially upon oxidation from 0.1 to up to 0.5. Together with changing MBT/ CBT values, this indicates preferential preservation of soil-derived branched GDGTs over marine isoprenoid GDGTs, combined with in situ production of branched GDGTs in the sediment. The TEX 86 value for IPL-derived GDGTs decreased by 0.07 upon oxidation, while that of CL GDGTs showed no significant change. Isolation of IPLs revealed that the TEX 86 value of monohexose GDGTs was 0.55, while the TEX 86 value for dihexose GDGTs was substantially higher, 0.70. Thus, the decrease in TEX 86 for IPL-derived GDGTs was in agreement with the dominance of monohexose GDGTs in the oxidized turbidite, probably caused by a combination of in situ production as well as selective preservation of terrestrial isoprenoid GDGTs. Due to the low amount of IPL GDGTs vs. CL GDGTs, the impact of IPL degradation on CL-based TEX 86 paleotemperature estimates is negligible.

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“…The detection limit of Ca is near 800 ppm. Accordingly, sediments with biogenic opal contents >15 wt% produce XRF counts of Ca that are weighed down by high contents of water and Si [Tjallingii et al, 2007], and are much lower than CaCO 3 contents measured by conventional chemical analyses.…”

Section: Ca Xrf Intensity and Caco 3 Contentsmentioning

confidence: 99%

Paleonutrient and productivity records from the subarctic North Pacific for Pleistocene glacial terminations I to V

Gebhardt¹,

Sarnthein²,

et al. 2008

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[1] Our study addresses fundamental questions of the mode and timing of orbital and millennial-scale changes in the meridional overturning circulation (MOC) of the subarctic North Pacific. Particular concerns are the vertical mixing, the present and past abundance of nutrients in surface waters despite strong stratification, and the North Pacific-North Atlantic seesaw of oscillations in sea surface temperature (SST). We do this by generating and interpreting multiple records for glacial terminations I-V down two long piston cores, one each from the western and eastern subarctic Pacific. Chlorins and biogenic opal are proxies for surface water productivity; d 13 C of epibenthic foraminifera is a record of deepwater ventilation; and the d 13 C of N. pachyderma sin. is a tracer of nutrients in subsurface waters that extend up to the sea surface during times of vertical mixing. The degree of mixing is traced by pairing SST and d 18 O records of planktic surface and subsurface (pycnocline) dwellers. Tight age control is deduced from a suite of age-calibrated 14 C plateau boundaries for Termination I and benthic d 18 O and geomagnetic events for the last 800 ka. Carbon 14 paleoreservoir ages record the ages of surface and deep waters to uncover short-term changes in MOC over Termination I. We have defined a standard sequence of short-term productivity events for Termination I, also evident during terminations II to V and subsequent interglacials over the last 450 ka. The peak glacial regime of stable stratification and low productivity terminated, together with the end of ice rafting and melting, near 17 ka, $2000 years after the onset of Termination I. Pulses of vertical mixing and incursion of warm surface waters from the subtropics followed. Convected young water masses finally penetrated down to 3600-m water depth at 17.0 to less than 14.5 ka, significantly improving bottom water ventilation through the late deglacial and earliest interglacial. Mixing with upwelled nutrients from the pycnocline induced short-term maxima in algal production of chlorins and biogenic opal near 17-15 and 15-12 ka, respectively. Deglacial meltwater incursions in the Aleutian Current and silica input from North American rivers also promoted East Pacific productivity after 15.5 ka. Productivity decreased during the late deglacial and early interglacial, coeval with an exceptional peak in CaCO 3 preservation caused by both low organic flux and well-ventilated deepwater. Subsequently, low salinity and cool surface waters and in turn, stratification were gradually restored. A second, opaldominated productivity maximum marked the ends of interglacials. The deglacial pulses of vertical mixing around 17-11 ka imply an important contribution of the North Pacific to the coeval release of oceanic CO 2 into the atmosphere and support the east-west seesaw model of climate change.Citation: Gebhardt, H., M. Sarnthein, P. M. Grootes, T. Kiefer, H. Kuehn, F. Schmieder, and U. Röhl (2008), Paleonutrient and productivity records from the subarctic North ...

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Influence of the water content on X‐ray fluorescence core‐scanning measurements in soft marine sediments

Cited by 381 publications

References 30 publications

Late Oligocene obliquity-paced contourite sedimentation in the Wilkes Land margin of East Antarctica: implications for paleoceanographic and ice sheet configurations

Late Oligocene obliquity-paced contourite sedimentation in the Wilkes Land margin of East Antarctica: implications for paleoceanographic and ice sheet configurations

Differential degradation of intact polar and core glycerol dialkyl glycerol tetraether lipids upon post-depositional oxidation

Paleonutrient and productivity records from the subarctic North Pacific for Pleistocene glacial terminations I to V

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