(a)
(b)
(c)
(d)
Figure 2: Approximate scale comparisons (near ~1 : 1) of previously reported “granular” bioalteration microtextures in submarine basaltic glass (a, c) with abiotic corrosion microtextures (granular palagonite ART alteration) in DSDP 418A basaltic glass (b, d) (this study; sample DSDP-418A-68-3[40–43]). All images are BSE images (acquired by SEM) of polished petrographic sections of submarine basaltic glasses. (a) is either from sample DSDP-417D-30-6-[20–24] (as reported in Figure  1(e) of [11]) or sample DSDP-418A-62-4-[64–70] (as reported in Figure  5(e) of [31] and Figure  2(c) of [28]), and (c) is from sample DSDP-504b-4-2-[0–20] (as reported in Figure  3(b) of [59], Figure  5(f) of [31], and Figure  2(d) of [28]). Note the similarities when comparing (a) and (c) with (b) and (d), respectively, despite the differences in their inferred origin (biotic versus abiotic). The 120 nm diameter pink circles in (d) correspond to “hypothetical” previously existing alpha-recoil tracks that have undergone selective palagonitization resulting in the formation of palagonite “granules” (or “granular” palagonite texture). ART: alpha-recoil track; f: fracture; f1: early fracture; P: palagonite.