strattotimepointcont: Transform Points and Isotope Ratios from Stratigraphic Height into Time (Continuos)

Description

This function takes a continuous deposition rate and reconstructs at what time a given stratigraphic height was deposited. Essentially a wrapper of pointtransform(...,direction='height to time',depositionmodel='piecewise linear deposition rate') kept for backwards compatibility of the package. It is recommended to use pointtransform instead of this function.

Usage

strattotimepointcont(x, xdep, ydep, hiatuslist = list(), unit = "sediment per time")

Arguments

Vector containing the stratigraphic heights whose time of deposition are to be determined

xdep

Vector of strictly increasing real numbers

ydep

Vector of the same length of xdep, containing strictly positive real numbers. xdep and ydep define the deposition rate in the sense that depositionrate=approxfun(xdep,ydep). The units of te deposition rate are by default "sediment per time" and can be changed using the optional input unit

hiatuslist

OPTIONAL, default is an empty list. A list of hiatuses to insert. Every entry in the list corresponds to a hiatus, which is given as a vector of length two. The first entry of the vector is the stratigraphic height of the hiatus, the second entry is the duration of the hiatus.

unit

OPTIONAL, default is "sediment per time". Either "sediment per time" or "time per sediment". Determines the unit that is assumed for the deposition rate.

Value

Returns a list containing

age

vector containing times of deposition of the stratigraphic heights given by the input x

height

vector containing the heights that were deposited at the times given by age. Essentially a duplicate of the input x

Output of NA in age indicates that some values coincide with a hiatus or are located at places where the deposition rate is undefined.

References

Hohmann, Niklas. 2018. Quantifying the Effects of Changing Deposition Rates and Hiatii on the Stratigraphic Distribution of Fossils. <doi:10.13140/RG.2.2.23372.51841>

Examples

Run this code

# NOT RUN {
##define deposition rate
xdep=seq(0,12,length.out=100)
ydep=splinefunH(x=c(0,2,4,6,8,10,12),y=c(1,5,6,1,0.5,1,6),m=c(0,1.5,-0.5,-0.5,0,0.5,0))(xdep)
#unit of deposition rate is sediment per time unit (default setting)
usedunit="sediment per time" #unit of deposition rate is sediment per time unit (default setting)
#Plot deposition rate
plot(xdep,ydep,type='l',main='Deposition Rate',xlab='Stratigraphic Height',ylab=usedunit) 

##at what time was the point with tratigraphic height 9 deposited?
strattotimepointcont(9,xdep,ydep) 

##create an age model
stratheight=seq(min(xdep),max(xdep),length.out=100)
usedunit="sediment per time"
reslist=strattotimepointcont(stratheight,xdep,ydep,unit=usedunit)
#plot age model
plot(reslist$age,reslist$height,xlab='Time',ylab='Stratigraphic Height',
  main=paste('Age model with unit',usedunit))
#create age model but with other units for sedimentn input
usedunit='time per sediment'
reslist=strattotimepointcont(stratheight,xdep,ydep,unit=usedunit)
#plot age model (note the difference this setting makes)
plot(reslist$age,reslist$height,xlab='Time',ylab='Stratigraphic Height',
  main=paste('Age model with unit',usedunit))

##create age model with a hiatus
stratigraphicheight=5 #strat. height of the hiatus
duration=2 #duration of the hiatus
hiatuslist=list(c(stratigraphicheight,duration)) #required input format for hiatuses
reslist=strattotimepointcont(stratheight,xdep,ydep,hiatuslist=hiatuslist)
#!using default setting for units again!
plot(reslist$age,reslist$height,xlab='Time',ylab='stratigraphic height')

##Transform isotope ratios
#create fake oxygen isotope curves
samplelocation=sort(runif(20,min=min(xdep),max=max(xdep))) #where the samples are taken
isotoperatio=sin(samplelocation)*rnorm(length(samplelocation)) #isotope ratios of the samples
plot(samplelocation,isotoperatio,type='l',xlab='Stratigraphic Height',ylab='Isotope Ratio')
#transform only (!) sample locations, NOT values
reslist=strattotimepointcont(samplelocation,xdep,ydep)
#Isotope ratios in time 
plot(reslist$age,isotoperatio,type='l',xlab='Time',ylab='Isotope Ratio')
# }