Microprobe U-Th-PbT Dating of Monazite: Top- Down, Bottom-Up or au Rebours?

Abstract

Extensive statistical characterization of individual
analyses, supported by chemical data, represents a highly
effective alternative in microprobe chemical dating of monazite,
preventing possibly arbitrary a priori grouping of analyses. Age
values and associated errors obtained for each analysis by error
propagation through an explicit approximation of the age
equation allow accurate subsequent statistical processing in
order to identify consistent and meaningful populations. A
procedure that involves seeking out of coherent clusters in
complex age spectra, assessment of the overall probability
distribution function, its deconvolution, and chemical
correlations opportunely complements the high spatial resolution
of the microprobe analyses, potentially highlighting the timing,
context and duration of intricate events and processes in the
thermotectonic evolution of igneous and metamorphic rocks.