Garnet zoning profiles

Fig. 4. Garnet zoning profiles from Domain II. (a) Inclusion-free garnet rim (Gamet-2) and the inclusion-rich core (Garnet-1) of a large composite grain, (b) Backscattered-electron image of newly nucleated Garnet-2 in the biotite-rich rock fabric, showing compositional differences in Garnet-2.

Fig. 7. Garnet zoning profiles from Domain V. (a) A subhedral garnet in 462536 with an inclusion-rich, Mn-rich core and a rim with fewer inclusions, (b) Deformed and altered garnet in 466466 showing Garnet-1 and Garnet-2 growth (garnet shown in crossed polars).

Fig. 8. A summary of garnet zoning profiles for the five structural domains of the Isua Greenstone Belt. The data are presented for fe-number, as an indicator of the thermal history of the grains, and show the generations of garnet in each domain, identified on the basis of their morphological, compositional and chemical-zonation differences.

Figure 5 (a) Compositional zoning profile collected across a single garnet from sample FH-IM, Tauern Window,... 

Figure 10 Zoning profiles collected at the outer edges of garnets from rocks with much less pronounced coronas show diffusional patterns over the outer —50 p.m. However, the coronal texture and increase in Mn towards rim unequivocally indicate operation of an ReNTR, which must have consumed part of the diffusion profile as it was growing. Thus, the apparent extent of diffusion is much lower than if the rim had been static. These profiles can be fitted to infer relative rates of cation diffusion (source Carlson, 2002).

Figure 19 (a) X-ray map and (b) compositional profile of yttrium across a garnet-zone garnet, showing slight... 

Figure 16 Oxygen isotope profiles across a garnet from Tierra del Fuego, Chile, showing general 0.5%c increase in from core to rim. This zoning is...

Compositional zoning. Garnet in pelite 466455 has an asymmetrical compositional profile. shows a flat-topped, bell-shaped profile, coinciding with the inclusion-rich core, but has lower concentrations in the inclusion-free rim. -Sca shows a similar, but more rounded profile and Mg and Ype show the converse, increasing in concentration from core to rim. 

Compositional zoning. Compositional profiles in both 462536 and 466466 are asymmetric. The altered domain in the core of the garnet in sample 466466 (Fig. 7b) has an Mn-rich bellshaped profile surrounded by an asymmetric rim... 

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