Xenotime dating website
Empirical correction factors calculated in this way broadly agree with correction factors calculated using the program Virtual WDS (Reed & Buckley, 1996; see also Scherrer , 1993).Prioritization of F analysis, 10 μm spot size, low current (∼20 n A on the Faraday cup) and short counting times (15 s on peak) were used to minimize F excitation.This age matches well with CHIME age of 1929 ± 130 Ma of xenotime.All the textural and geochemical characteristics of the grains suggest that the xenotime is of retrograde metamorphic origin which occurs after D1 phase of deformation, hence constraining the upper age limit of the Udayagiri Domain to be 1929 ± 130 Ma.The Nellore Schist Belt (NSB) is a curvilinear Archaean schist belt, approximately 350 km long and 8-50 km wide.The Nellore Schist Belt is considered to be equivalent of the Sargur Group with a protolith age of 3.3-2.5 Ga.We attempt to demonstrate that metamorphic monazite approaches compositional equilibrium with both coexisting major and accessory phases.
Monazite grains that grew in equilibrium with xenotime are enriched in Y and Dy compared with monazite that grew in xenotime-absent assemblages.
During recent mapping, in the central western part of NSB, west of Pamuru town, in a metapellite of Udayagiri Domain (consisting mainly of quartz, muscovite, paragonite, Spessartine garnet, chlorite, chloritoid and magnetite as accessory mineral) four small grains of Xenotime has been found, among which three grains have been dated.
Xenotime is a rare earth phosphate mineral whose major is Yttrium orthophosphate (YPO4).
Textural relationships between monazite and other accessory phases (allanite, apatite, epidote, titanite) indicate that monazite is involved in reaction relationships with other REE-accessory minerals (Broska & Siman; 1998; Finger , 1996; Pan, 1997; Ferry, 2000).
This paper focuses on monazite, xenotime, garnet, and, to a lesser extent, apatite because (1) they are significant geochronometers, (2) a large portion of a typical pelite REE and Y budget is contained in these phases, and (3) zoning in garnet and monazite record significant details of the reaction history.