Variations in trace elements determined by LA-ICP-MS in thin sections between zircon crystals associated with mafic polyphase and granophyre mineral assemblages in UZa’ (SK08-154, panels a–d) and LZa’ (SK08-190, panels e-i). (a) SEM-CL image of a skeletal zircon in UZa’ (SK08-154) with LA-ICP-MS spot locations (ablation spots = 19 μm) shown by coloured circles. (b) Concentrations of U, Hf, and Ti (all in ppm) for spot analyses shown in panel (a); coloured circles correspond to spot locations. (c) Diagram of Th vs U for spot analyses shown in panel (a). Dashed lines represent constant values of Th/U; coloured circles correspond spot locations in panel (a). (d) Diagram of Ti vs Hf for spot analyses shown in panel (a); coloured circles correspond spot locations in (a). (e and f) Photomicrographs and CL images for zircon from LZa’ (SK08-190) showing examples of (e) mafic polyphase and (f) granophyre interstitial pockets containing zircon in LZa’. The circles indicate the locations of LA-ICP-MS spot analyses (diameter = 19 μm). (g) Chondrite-normalized REE patterns in zircon grains in polyphase and granophyre interstitial pockets from LZa’ (SK08-190). Average values for individual samples are represented by lines and symbols and the range of all values within a sample is indicated by shaded areas. Chondrite-normalizing values from McDonough & Sun (1995). (h) Th vs U from LZa’ (SK08-190); dashed lines represent constant values of Th/U. (i) Ti vs Hf in zircon from LZa’ (SK08-190) determined to have crystallized in either mafic polyphase, granophyre, or mixed mafic polyphase-granophyre assemblage interstitial pockets.