Figure 3
From: Garnet, the archetypal cubic mineral, grows tetragonal
Compositional patterns and inhomogeneities in the studied garnets. (a) Series of images showing, from left to right, optical and BSEM view of a sector-zoned garnet from Cazadero, followed by the X-ray maps with the distribution of Mn, Ca and Fe. White arrows point to Ca-high, Fe-low layers, black arrows to Ca-low, Fe high layers in the oscillatory-zoned part of the crystal. The A-A’ line corresponds to the EMP transect reported in (c). (b) Details of a zone with marked mottled birefringence in a garnet from Jenner. From left to right optical and BSEM views, Ca and Fe X-ray maps of the same area. Arrows like in (a). The C-C’ line corresponds to the EMP transect reported in (c). (c) Major element compositional features in crystals of blueschists along transects in Figs 1f and 3a,b. A-A’: Cazadero: transect from rim (A) to core (A’) of crystal. The features related to oscillatory zoning are apparent on the left part of profile. B-B’: Farinole and C-C’: Jenner. Details of the bands and patches of Ca-Fe variations. Peaks and troughs have maximum widths of 10–20 μm. For all transects the vertical arrows locate the counterbalancing variations of Ca and Fe mirroring each other.
