![]() The microscopic healing time was strongly dependent on temperature and roughness of the interface and was, for the nonpolished interfaces, 67–74, 4.0–4.9, and 0.36–0.38 h at 850°, 900°, and 950☌, respectively, whereas for the polished examples it was 1–3 and 0.5–0.6 h at 850° and 900☌, respectively. We defined this closure interval as microscopic healing time and determined this by fitting the measured profiles with a diffusion model. This change was interpreted to reflect atomic-scale closure of the interface, probably by chemical bonding. The water content across the contact initially decreased toward the interface via diffusive dehydration, but later homogenized. The contact interface became coherent and finally disappeared. ![]() These were annealed in an open-system cell. Two cylindrical obsidian cores were juxtaposed on surfaces prepared by cutting the cores both with and without polishing. To estimate the healing time of magmatic fractures, we performed healing experiments on rhyolitic melts at 850°–1000☌ and 1.6–3.2 MPa for 0.5–94 h. ![]() The healing of magmatic fractures is considered essential to repetitive seismicity and the closure of degassing paths during emplacement of lavas.
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