Modelling the effects of sediment compaction on salt marsh reconstructions of recent sea-level rise

Abstract

. (2012) 'Modelling the eects of sediment compaction on salt marsh reconstructions of recent sea-level rise.', Earth and planetary science letters., 345-348 . pp. 180-193. Further information on publisher's website:http://dx.doi.org/10.1016/j.epsl.2012.06.045Publisher's copyright statement: NOTICE: this is the author's version of a work that was accepted for publication in Earth and Planetary Science Letters. Changes resulting from the publishing process, such as peer review, editing, corrections, structural formatting, and other quality control mechanisms may not be reected in this document. Changes may have been made to this work since it was submitted for publication. A denitive version was subsequently published in Earth and Planetary Science Letters, 345348, 2012Letters, 345348, , 10.1016Letters, 345348, /j.epsl.2012 Additional information: Use policyThe full-text may be used and/or reproduced, and given to third parties in any format or medium, without prior permission or charge, for personal research or study, educational, or not-for-prot purposes provided that:• a full bibliographic reference is made to the original source • a link is made to the metadata record in DRO • the full-text is not changed in any way The full-text must not be sold in any format or medium without the formal permission of the copyright holders.Please consult the full DRO policy for further details. AbstractThis paper quantifies the potential influence of sediment compaction on the magnitude of nineteenth and twentieth century sea-level rise, as reconstructed from salt marsh sediments.We firstly develop a database of the physical and compression properties of low energy intertidal and salt marsh sediments. Key compression parameters are controlled by organic content (loss on ignition), though compressibility is modulated by local-scale processes, notably the potential for desiccation of sediments. Using this database and standard geotechnical theory, we use a numerical modelling approach to generate and subsequently 'decompact' a range of idealised intertidal stratigraphies. We find that compression can significantly contribute to reconstructed accelerations in recent sea level, notably in transgressive stratigraphies. The magnitude of this effect can be sufficient to add between 0.1 and 0.4 mm yr -1 of local sea-level rise, depending on the thickness of the stratigraphic column. In contrast, records from shallow (< 0.5 m) uniform-lithology stratigraphies, or shallow near-surface salt marsh deposits in regressive successions, experience negligible compaction. Spatial variations in compression could be interpreted as 'sea-level fingerprints'that might, in turn, be wrongly attributed to oceanic or cryospheric processes. However,

Quantifying the Contribution of Sediment Compaction to late Holocene Salt-Marsh Sea-Level Reconstructions, North Carolina, USA

“…We estimated σ' y by determining the vertical effective stress at which best-fit recompression and compression lines intersected in elogσ' space (cf. Brain et al 2012).…”

“…These measurements characterized the sediment and were used in compaction model equations (Brain et al, 2012). Reported LOI values for each surface sample represent the mean of three determinations to assess variability in small sample masses (approximately 2 g of dry mass following desiccation to determine moisture content; see Heiri et al, 2001) (Table 2).…”

“…We sampled TP12 by slicing the core into 2 cm thick contiguous samples, which is the approximate height of a typical oedometer sample (Brain et al, 2012). For each core sample, we estimated organic content by LOI and measured bulk density following the methods described by Head (1980).…”

“…The model has not previously been applied to, or validated in, a real-world sedimentary succession (cf. Brain et al, 2012).…”

Sea-level changes in Iceland and the influence of the North Atlantic Oscillation during the last half millennium

“…This is in agreement with the compaction studies of Brain et al (2012) To calculate error envelopes for our sea-level reconstruction we resampled the RSL data points in R using their individual age and vertical error estimates. For each of 1,000…”