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.