Application of grouped detrital zircon analyses to determine provenance and closely approximate true depositional age: Early Cretaceous McMurray-Clearwater succession, Canada

In the Lower Cretaceous McMurray-Clearwater succession of the intracontinental Alberta Foreland Basin, Canada, detrital zircon U-Pb geochronology samples (referred to herein as DZ samples) have been used to interpret the strata as representing a paleo-continental-scale drainage system. However, the majority of DZ samples are relatively small (n≈90–100), and syndepositional DZ (i.e., crystallization age 5% of the total DZ population), calculating maximum likelihood ages from grouped DZ samples avoids negatively biased (i.e., too young) MDAs. We suggest grouped DZ samples and the gMDA method be used in systems with multiple DZ samples from a well-defined stratigraphic interval as a means of assessing variability in provenance within a depositional system and for improving estimates of depositional ages us