Discovery of Naturally Etched Fission Tracks and Alpha-Recoil Tracks in Submarine Glasses: Reevaluation of a Putative Biosignature for Earth and Mars

Figure 16

Diagram summarizing the “abiotic driving mechanism” for the formation of complex corrosion microtextures (i.e., microscopic etch-tunnels and granular palagonite) in DSDP 418A basaltic glass: the concomitant increase in hydrostatic pressure and accumulation of radiation damage in basaltic glass with aging of the oceanic crust. The following is depicted in this diagram: (i) the depth-age relationships for volcanic basement in the oceanic crust—depicted as the average depth to basement below sea level (b.s.l.) (corrected for sediment load) for the southwestern North Atlantic Ocean (jagged blue line; from Sclater and Wixon [209]); (ii) the location of DSDP Hole 418A (note that the actual top of volcanic basement in this drill hole is slightly lower than the southwestern North Atlantic average (jagged blue line)); (iii) the inferred hydrostatic pressure in the water column (which can be read at right, along with ocean depth); and (iv) curves (although they are nearly straight lines in this plot) depicting the accumulation (dose) of radiation damage in basaltic glass group “J” (g.g. “J” in Figure 5(b)) through time—that is, the systematic increase (with age) in model fission track and alpha-recoil track areal densities intersecting a hypothetical flat fracture plane through DSDP 418A basaltic glass (calculated using (1) and (2)).