The Open UniversitySkip to content
 

The significance of monazite U–Th–Pb age data in metamorphic assemblages: a combined study of monazite and garnet chronometry

Foster, Gavin; Kinny, Pete; Prince, Christophe; Vance, Derek and Harris, Nigel (2000). The significance of monazite U–Th–Pb age data in metamorphic assemblages: a combined study of monazite and garnet chronometry. Earth and Planetary Science Letters, 181(3) pp. 327–340.

DOI (Digital Object Identifier) Link: http://dx.doi.org/10.1016/S0012-821X(00)00212-0
Google Scholar: Look up in Google Scholar

Abstract

In this study, a coupled U–Th–Pb isotopic and EMP chemical study was carried out in situ on monazite (micro-inclusions within garnet as well as matrix grains) from rocks recovered from two chronologically well-constrained areas of the Himalayan orogen. Monazite inclusions within garnets from three samples yield ages of 44–36 Ma, whereas matrix grains within one sample are typically younger (30–26 Ma). Y depletion of these younger matrix grains indicates that they grew after garnet had crystallised. The recognition of episodic monazite growth during regional metamorphism, first at greenschist facies (before garnet growth) and secondly at upper amphibolite facies (post-dating garnet growth), allows relative growth ages of the occluding garnet to be calculated. These are in excellent agreement with Sm–Nd garnet ages from surrounding units. This approach not only provides a ready means of obtaining porphyroblast growth ages but also allows the combination of precise U–Th–Pb data from metamorphic monazite with thermobarometric information obtained from rock-forming minerals.

Item Type: Journal Article
ISSN: 0012-821X
Keywords: monazite; absolute age; isotope ratios; U/Th/Pb; Sm/Nd; secondary ion mass spectroscopy
Academic Unit/Department: Science > Environment, Earth and Ecosystems
Interdisciplinary Research Centre: Centre for Earth, Planetary, Space and Astronomical Research (CEPSAR)
Item ID: 11838
Depositing User: Nigel Harris
Date Deposited: 30 Sep 2008 12:05
Last Modified: 02 Dec 2010 20:12
URI: http://oro.open.ac.uk/id/eprint/11838
Share this page:

Actions (login may be required)

View Item
Report issue / request change

Policies | Disclaimer

© The Open University   + 44 (0)870 333 4340   general-enquiries@open.ac.uk