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Journal of Paleolimnology

, Volume 46, Issue 2, pp 173–186 | Cite as

Could bulk density profiles provide information about recent sedimentation rates?

  • José-María Abril
Original paper

Abstract

Independent validation has to be an integral part of the 210Pb-based radiometric dating of recent sediments. The combined use of artificial fallout radionuclides leads to serious problems because only the identification of peaks and their use as time-marks is not sufficiently rigorous to ensure the accuracy of dates. Quantitative modelling of depth profiles requires reliable input functions, which can be substantially different from the atmospheric deposition records. The appropriate treatment of compaction is another source of complexity. Continuum mechanics provide a suitable framework to understand compaction in sedimentary basins with length scales of several km. Nevertheless, early compaction (with length scales of few cm at the sediment surface) takes place under hydrostatic equilibrium conditions, and it can be better understood as a transport phenomenon: a mass flow governed by spatial gradients of a compaction-potential energy, involving a conductivity function. This paper explores some analytical and numerical solutions for these equations to provide insight about the early compaction phenomenon. Given a conductivity function and a constant sedimentation rate, the system will evolve towards a steady-state profile for bulk density. The fingerprint of variable sedimentation rates, among other changes in environmental conditions, will be studied with numerical solutions. Finally, the paper explores the use of bulk density profiles for deriving information on recent sedimentation rates, which could provide independent support for the radiometric dating models.

Keywords

Bulk density Early compaction Sedimentation rate Radiometric dating Mass depth 

Abbreviations

SWI

Sediment–water interface

ECL

Early compaction limit

Supplementary material

10933_2011_9520_MOESM1_ESM.doc (100 kb)
Supplementary material 1 (DOC 100 kb)
10933_2011_9520_MOESM2_ESM.doc (105 kb)
Supplementary material 2 (DOC 105 kb)
10933_2011_9520_MOESM3_ESM.ppt (146 kb)
Figure 1 (ESM) Excess 210Pb specific activity versus depth for a sediment core from an Alpine lake (data from Erlinger et al. 2008; their core-1). Supplementary material 3 (PPT 144 kb)
10933_2011_9520_MOESM4_ESM.ppt (162 kb)
Figure 2 (ESM) As in Fig. 7, but using the mass depth variable. Curve R11 corresponds to model output using the best fit (to Eq. 13, coincident with R11) as initial conditions, a constant w 0 = 0.1 g cm−2 year−1 and C m  = 0.206 year−1 (from Eq. 15). Curve R12 is as R11, but with the time-dependent w 0 given by Fig. 6 and C m  = 0.114 year−1 (from the mean value of w 0). R13 is the best fit (χ v  = 1.39) obtained by excluding the five uppermost data points (α m  = 0.826 cm2g−1, \( \rho_{\infty } = 0.447;\,\rho_{1} = 0.392 \) g cm−3). Supplementary material 4 (PPT 160 kb)

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Copyright information

© Springer Science+Business Media B.V. 2011

Authors and Affiliations

  1. 1.Dpto. Física Aplicada IUniversidad de SevillaSevilleSpain

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