Recovering tectonic events from the sedimentary record: Detrital monazite plays in high fidelity

Measurement of detrital zircon U-Pb ages has become the method of choice for single crystal-based investigations of provenance for both modern and ancient sediments. Recent studies, however, demonstrated the failure of zircon to record major tectonic events in source terranes, revealing the need for a more robust provenance methodology. A direct comparison between the utility of crystallization ages of detrital zircon and monazite as provenance indicators has been made using modern river alluvium derived from known sources. While detrital zircon does not fully record the multiple collisional phases that are the hallmark of the Appalachian orogen, detrital monazite accurately records all the major tectonic events. The physical and petrogenetic differences between zircon and monazite are the primary factors for differing detrital age spectra. Zircon, owing to its extreme refractory nature, skews detrital age spectra toward older ages and limits its ability to record low-grade thermotectonic events in orogens. Monazite recrystallizes over a broader range of metamorphic conditions than does zircon. Consequently, monazite has the potential to record metamorphic events that might otherwise be absent from the detrital zircon record, thus providing a more accurate record of source terranes in regions characterized by moderate thermal events.