Quantitative comparison of large sets of geochronological data using multivariate analysis: a provenance study example from Australia

Abstract

A variety of modern isotopic analytical techniques now allow the relatively rapid acquisition of large sets of geochronological data, particularly in provenance studies. Traditional interpretation of this type of data often relies on visual comparison techniques that are vulnerable to subjective bias and this problem becomes acute with increasingly large quantities of data. Multivariate techniques are presented in this article to objectively evaluate age components within the detrital zircon age data from 31 beach sand and sedimentary samples in Australia for provenance studies. Using the SHRIMP Ion Microprobe each sample typically contains 60 or more individual age measurements with a combined total of 2150 analyses. Principal components derived from the data set allow the construction of provenance models that are independent of expected age components. In this instance the principal components are interpreted in terms of existing knowledge about Australian geology, in particular the provenance relationship between “local” Phanerozoic-aged and “exotic” late Proterozoic-aged protosources. Using principal components analysis this relationship is seen clearly and objectively in one diagram illustrating provenance evolution along the eastern coastline.