Materials and Methods
The LABLASTER package contains one function named endPoint that
calculates four items, and four example data sets to illustrate its use,
including the foraminifer and coral examples presented here. The package
requires R (≥ 3.5.0)12 and has a number of
dependencies as it calls functionality from the
stats12, smooth13, ggplot2,
magrittr14 and scales15 packages.
endPoint detection
The main function of the LABLASTER package is to detect when
either the laser has ablated through a target (e.g., a carbonate shell
or coral skeleton) or across a boundary in a transect. In the following
sections, we illustrate this behaviour on a planktic foraminifer and a
tropical coral as case studies.
Identifying the time range in a time resolved acquisition when the laser
is ablating the target is essential for accessing and correlating the
relevant data within the recorded time series. The LABLASTER
package assumes the data frame supplied begins with the laser in focus
of the desired target and the endPoint function determines the time
stamp when the laser has ablated through the sample or across a boundary
where the isotope signal changes rapidly. Keeping only the data between
the start time and end time focusses subsequent analysis on only
relevant target data.