Table 2

Description of zircon morphology within igneous basement samples from Oman

SampleZircon colourZircon, shape, size and aspect ratioCL characteristics
MR15-01Pale brownShape pyramidal {101}; Aspect ratio 4:1 and 2:1; Size 100–350 µmGrains preserve a homogeneous core, with varying development of oscillatory-zoned bands. Complex growth zoning with local intermediate resorption in some places. Most grains are not luminescent and are CL dark
MR15-02Pale brown or colourlessShape prismatic {100}, {211}; Aspect ratio 3:1, 4:1 and 2:1; Size 100–400 µmOscillatory zoning and sector zonation preserved in some grains. There are strong variations in the relative development of zoned domains, where one large uniform central zone is succeeded by much finer oscillatory-zoned bands. Zircons have segments of homogeneously textured zircon appearing as transgressive (across all pre-existing textures) zircon patches and lobes
MR15-04Pale orange or colourlessShape prismatic or pyramidal {101}, {211}, although grains exhibit rounded edges; Aspect ratio 3:1, 4:1 and 2:1; Size 100–400 µmMost grains have oscillatory zoning, although relative development of oscillatory bands varies. Zircons have segments of homogeneously textured zircon appearing as transgressive (across all pre-existing textures) zircon patches and lobes. Areas of recrystallization occur dominantly at crystal terminations
MR15-05Pale orange or colourlessShape pyramidal {101}, grains have mostly rounded edges; Aspect ratio 2:1 and 1:1; Size 100–400 µmSector zonation dominates. Oscillatory zoning is present, although faint in most grains. Recrystallization or new growth is seen cutting well-defined oscillatory-zoned euhedral core
MR15-07Pale yellow or orangeShape prismatic {100}, {110}, mostly with some rounded or more rounded zircons; Aspect ratio 2:1, 1:1 and 5:2; Size 100–400 µmRelative development of oscillatory zonation varies. Some grains exhibit homogeneous cores, with finer oscillatory zoning towards the edge of the grain. Some recrystallization or newly grown homogeneous zircon seen cutting the euhedral grain, although rare
AJ14-19Pale yellow or orangeShape pyramidal {101}; Aspect ratio 2:1, 7:2 and 5:2; Size 50–150 µmSome grains are homogeneous with a thin dark rim mantling the grain. Others preserve large homogeneous cores, with fine oscillatory bands defining the rims. Some cases have complex feathery textures. Areas of recrystallization present, mainly at crystal terminations
AJ14-23Pale brown or pale orangeShape pyramidal {101}; Aspect ratio 2:1, 7:2 and 5:2; Size 70–250 µmGrains are largly homogeneous with a few oscillatory growth bands defining the rims. Grains are largely featureless
AJ14-25Colourless or pale yellowShape pyramidal {101}; Aspect ratio 3:1, 4:1, 7:1 and 7:2; Size 100–200 µmMajority of the grains are homogeneous no defining features. Other grains have a large uniform central zone that is succeeded by much finer oscillatory-zoned bands
O14-04Pale yellow or orangeShape pyramidal {101}; Aspect ratio 4:1 and 2:1; Size 50–250 µmGrains have well-defined oscillatory zonation, although relative development of zones varies across the sample. Zircons have segments of homogeneously textured zircon appearing as transgressive (across all pre-existing textures) zircon patches and lobes
O14-08Pale orange or colourlessShape pyramidal {101} and sub-rounded grains; Aspect ratio 4:1 and 2:1; Size 100–200 µmOscillatory zoning present, although in some grains zonation is faint. Grains contain areas of recrystallization, evident by lobes and patches seen in the zircon
MR15-14Colourless, pale brown or pale orangeShape {101} and {211}; Dominant aspect ratio is 2:1, with some rounded 1:1 grains; Size 100–300 µmTwo main groups of zircon. Group 1 is dominated by grains with prismatic forms. They are characterized by oscillatory zoning of varying thickness. A few grains show signs of recrystallization (in the form of lobes and patches). Group 2: small rounded grains have a CL dark core with thin bright rims. Some of the rounded grains have well-defined oscillatory zoning
JA15-43Pale yellow or orangeShape pyramidal {101} and {211}; rounded grains present Aspect ratio 4:1, 5:1, 2:1 and 1:1; Size 50–200 µmWell-defined oscillatory zonation. Cores are present, although textures suggest they are metamict. Some grains display areas of recrystallization, with overprinting of the pre-existing texture. CL bright rims are seen mantling a few grains

MR, Mirbat; AJ, Al Jobah; O, Jebel Akhdar; JA, Jebel Ja'alan.