BioturbationWeights {sedproxy}

Bioturbation weights

Description

For a given focal depth (or time), this function returns the probability that material collected from that depth was originally deposited at depth(s) z. In other words, that the material would have been found at depth z if there had been no bioturbation. It is the convolution of the depth solution from Berger and Heath (1968) with a uniform distribution to account for the width of the sediment layer from which samples were picked/extracted. It is a probability density function.

Usage

BioturbationWeights(
  z,
  focal.z,
  layer.width = 1,
  sed.acc.rate,
  bio.depth,
  scale = c("time", "depth")
)

Arguments

z

A vector of times or depths at which to evaluate the bioturbation weights

focal.z

The depth (or time) for which source dates are wanted

layer.width

the width of the sediment layer from which samples were taken, e.g. foraminifera were picked or alkenones were extracted, in cm. Defaults to 1 cm. If bio.depth and layer.width are both set to zero, each timepoint samples from a single year of the clim.signal, equivalent to sampling an annually laminated sediment core.

sed.acc.rate

Sediment accumulation rate in cm per 1000 years. Defaults to 50 cm per ka. Either a single value, or vector of same length as "timepoints"

bio.depth

Depth of the bioturbated layer in cm, defaults to 10 cm.

scale

Whether to scale depths by sediment accumulation rate to give positions in terms of time. Defaults to time.

Value

a numerical vector of weights.

References

Berger, W. H., & Heath, G. R. (1968). Vertical mixing in pelagic sediments. Journal of Marine Research, 26(2), 134–143.

Examples

z <- 0:10000
w <- BioturbationWeights(z, focal.z = 4000, layer.width = 1, sed.acc.rate = 5, bio.depth = 10)
plot(z, w, "l")