ELECTRONIC APPENDIX 3
Zircon morphology and texture descriptions, studied zircons
Weld River
WRT 01. Equant to prismatic and tabular grains include some with fine fractures. In CL imagery, one large
older age grain contains fine dendritic inclusion-bearing decompression fractures (Fig. 4f). The younger age
zircons exhibit close-spaced, regular oscillatory growth zonation, with more complex sector growth zones in
core regions.
Yarrowitch
YAR05a. Grains are slightly to strongly embayed, some contain abundant minute mineral inclusions and one
grain is highly fragmented. In CL imagery most grains exhibit closely-spaced oscillatory growth zonation,
some with growth dislocations. Other grains lack CL features or have a prominent bright central CL band
(twin plane?).
YAR05b, YAR05c. Largely uniform equant grains, all exhibit close-spaced oscillatory growth zones and in
some very complex sector growth zones, some centred on minute inclusions.
YAR05d. A large, partly embayed and fractured prismatic grain in CL imagery reveals close-spaced
oscillatory growth zonation, in which some zones are offset by inclusions and fractures.
Mount McLean
MMl01. A wide range of anhedral to subhedral, equant to prismatic grains include some with fine fractures
that have propagated along inclusion trails. In CL imagery, most grains have fine-spaced oscillatory
zonation, some with complex sector growth zones in their core region.
Ban Huai Sai
BHSL Z2. Relatively uniform, moderately to strongly embayed crystals, commonly contain abundant minute
mineral inclusions and show some fracturing around these inclusions. CL imagery invariably shows closespaced oscillatory growth zones. Bright CL zones along fractures suggest remobilization and associated loss
of U content.
Gia Nghia
GNZ4. Uniform shaped large prismatic grains, some of which show fine, close-spaced oscillatory growth
zones in CL imagery. One oscillatory-zoned, rimmed grain has very fine dendritic fracturing and unusual
wavy undulose CL banding. This grain also has a curvilinear structural plane (also prominent in BSE
imaging) that separates more U-rich zoned zircon from a highly brecciated U-depleted zone.
Podgelbanochny
PBV01A, PBV01B. Slightly and moderately embayed equant to prismatic and sometimes tabular grains, some
moderately fractured. Some grains contain abundant minute opaque, subhedral to euhedral, platy mineral
inclusions. Others have small radiating aggregates of euhedral platy prismatic negative crystal inclusions with
a sphenoidal habit. In CL imagery most exhibit well-developed, close-spaced oscillatory zonations although
in some grains this is less pronounced and confined to rims. Darker cores in some grains indicate a U-rich
zone (Corfu et al. 2003).
Reference
Corfu F, Hanchar JM, Hoskin PWO, Kinny P (2003). Atlas of zircon textures. In: Hanchar JM, Hoskin, PWO
(eds) Zircon. Rev Mineral Geochem 53: 469–500.
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