Figure 3. Representative thin section microphotographs and
scanning electron microscopic images of samples from the East Pilbara
Terrane. Pilbara samples show complete serpentinization, yet their
primary rock textures are preserved by serpentine pseudomorphs.a: Sample AW52614-4A shows compacted olivine-shaped serpentine
clusters (ii) which locally form polygonal textures (featured
by abundant 120° triple junctions). b: Alteration minerals such
as chlorite, serpentine and magnetite occur in interstitial spaces(i) and veins in sample AW52614-4A (ii). Inc.ii, c.iii and c.iv, two sets of serpentine
clusters are recognized with the cross-polarized light photomicrographs.
One set shows black/dark grey color, with outlines similar to olivine
grains. Another set is in white/light grey, which appears to enclose the
serpentine clusters of the first set. This texture resembles cumulate
textures, where smaller chadacrysts could be included in larger
oikocrysts. Mineral abbreviations: chl: chlorite; Cr-sp: Cr-spinel; mag:
magnesite; mgt: magnetite; ol: olivine; opx: orthopyroxene; serp:
serpentine;
Table 1: Mineralogy and location information of investigated samples.