Preservation of forcing signals in shallow water carbonate sediments. Hill, J., Wood, R., Curtis, A., & Tetzlaff, D. M. Sedimentary geology, 275-276(1):79–92, July, 2012.
doi  abstract   bibtex   
No consensus has been reached on whether the metre-scale cycles that commonly occur in peritidal carbonates are predominately a product of external relative sea-level variations (allocycles) or an intrinsic property of carbonate production generated via the interaction of non-linear processes (autocycles). For any forcing signal such as eustatic sea-level change, to be detectable in stratigraphy its effects must be preserved. Here, a deterministic, three-dimensional geological process model is used to explore how such cycles are preserved in the geological record in the presence of autocyclic processes. Each simulation produced cycle thickness distributions that are statistically indistinguishable from a theoretical Poisson process, regardless of whether auto- or allo-cycles dominated. Spectral analysis of depositional time series constructed from idealised geological sections showed that all detectable signals occurred within the Milankovitch forcing frequency bands, even when no Milankovitch forcing was present. Thus, it is deduced that from any geological section alone, external forcing signals are detectable but are not distinguishable from autocyclically produced signals. Interestingly, there is no correlation between the percentage of sediment preserved and the accuracy with which signals are detectable in the preserved sediment: in some model realisations, even with preservation as low as 40%, the correct forcing signal can be detected accurately while, conversely, sections with preservation as high as 90% can have poor signal preservation. The reverse can also be true in other models. It is therefore concluded that distinguishing allocyclic and autocyclic forcing in shallow marine or peritidal carbonate successions is likely to be extremely difficult except in cases of extraordinary sedimentary preservation and dating accuracy.
@ARTICLE{Hill2012-gg,
  title    = "{Preservation of forcing signals in shallow water carbonate
              sediments}",
  author   = "Hill, Jon and Wood, Rachel and Curtis, Andrew and Tetzlaff,
              Daniel M.",
  abstract = "No consensus has been reached on whether the metre-scale cycles
              that commonly occur in peritidal carbonates are predominately a
              product of external relative sea-level variations (allocycles) or
              an intrinsic property of carbonate production generated via the
              interaction of non-linear processes (autocycles). For any forcing
              signal such as eustatic sea-level change, to be detectable in
              stratigraphy its effects must be preserved. Here, a
              deterministic, three-dimensional geological process model is used
              to explore how such cycles are preserved in the geological record
              in the presence of autocyclic processes. Each simulation produced
              cycle thickness distributions that are statistically
              indistinguishable from a theoretical Poisson process, regardless
              of whether auto- or allo-cycles dominated. Spectral analysis of
              depositional time series constructed from idealised geological
              sections showed that all detectable signals occurred within the
              Milankovitch forcing frequency bands, even when no Milankovitch
              forcing was present. Thus, it is deduced that from any geological
              section alone, external forcing signals are detectable but are
              not distinguishable from autocyclically produced signals.
              Interestingly, there is no correlation between the percentage of
              sediment preserved and the accuracy with which signals are
              detectable in the preserved sediment: in some model realisations,
              even with preservation as low as 40\%, the correct forcing signal
              can be detected accurately while, conversely, sections with
              preservation as high as 90\% can have poor signal preservation.
              The reverse can also be true in other models. It is therefore
              concluded that distinguishing allocyclic and autocyclic forcing
              in shallow marine or peritidal carbonate successions is likely to
              be extremely difficult except in cases of extraordinary
              sedimentary preservation and dating accuracy.",
  journal  = "Sedimentary geology",
  volume   = "275-276",
  number   =  1,
  pages    = "79--92",
  month    =  jul,
  year     =  2012,
  keywords = "carbonate sedimentation,cyclicity,forward
              modelling,preservation,spectral analysis",
  issn     = "0037-0738",
  doi      = "10.1016/j.sedgeo.2012.07.017"
}

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