Monazite geochronology

Illustration showing age map and zonation pattern of a monazite grain. Brighter colour represents older age. Edited after Williams, 1999.[1]

Monazite geochronology is a dating technique to study geological history using the mineral monazite. It is a powerful tool in studying the complex history of metamorphic rocks particularly, as well as igneous, sedimentary and hydrothermal rocks.[2][3] The dating uses the radioactive processes in monazite as a clock.

The uniqueness of monazite geochronology comes from the high thermal resistance of monazite, which allows age information to be retained during the geological history.[3][4][5] As monazite grows, it forms successive generations of different compositions and ages, commonly without erasing the previous ones, forming zonation patterns in monazite.[2] Because of the age zonation, dating should be done on individual zones, rather than the whole crystal. Also, textures of monazite crystals may represent certain type of events. Therefore, direct sampling techniques with high spatial resolution are required, in order to study these tiny zones individually, without damaging the textures and zonations.[3]

The advantage of monazite geochronology is the ability to relate monazite compositions with geological processes. Finding the ages of compositional zones can mean finding the ages of geological processes.

  1. ^ Williams, M. L., Jercinovic, M. J., & Terry, M. P. (1999). Age mapping and dating of monazite on the electron microprobe: Deconvoluting multistage tectonic histories. Geology, 27(11), 1023–1026.
  2. ^ a b Williams, M. L., Jercinovic, M. J., & Hetherington, C. J. (2007). Microprobe monazite geochronology: understanding geologic processes by integrating composition and chronology. Annual Review of Earth and Planetary Sciences, 35(1), 137.
  3. ^ a b c Williams, M. L., & Jercinovic, M. J. (2002). Microprobe monazite geochronology: putting absolute time into microstructural analysis. Journal of Structural Geology, 24(6), 1013–1028.
  4. ^ Crowley, J. L., & Ghent, E. D. (1999). An electron microprobe study of the U–Th–Pb systematics of metamorphosed monazite: the role of Pb diffusion versus overgrowth and recrystallization. Chemical Geology, 157(3), 285–302.
  5. ^ Cite error: The named reference Smith1997 was invoked but never defined (see the help page).