Publikationsdatum:
2022-03-25
Beschreibung:
On-fault processes during earthquakes contribute to seismic rupture propagation and slip. Here we investigate clast fragmentation in an experimental pseudotachylyte (solidified seismic melt) produced with a rotary shear machine. We slid for 0.44 m (corresponding to Mw ≥ 6 earthquakes), at slip rates 〉 1 m/s, pre-cut samples of quartz + phyllosilicates + plagioclase + sillimanite + garnet -bearing ultramylonite, that hosts pseudotachylytes in nature. The ultramylonite minerals extensively preserved as clasts in the experimental pseudotachylyte are quartz, plagioclase, and sillimanite. Garnet is scarcely preserved, despite having a melting temperature similar to plagioclase, probably due to having low thermal shock resistance. This selective clast survival is identical to the one found in the natural pseudotachylytes. Based on these experimental observations and assuming non-equilibrium melting, the preservation of a mineral, as a clast, in the melt appears to be controlled by its thermal shock properties as well as by its melting temperature. Since the mechanical effects of rupture propagation in these experiments were negligible, we conclude that, for Mw ≥ 6 earthquakes, (i) frictional slip and heating of the slipping zone plus (ii) thermomechanical properties of minerals, rather than fault rupture processes, control mineral comminution and clast survival in frictional melts.
Beschreibung:
This work was supported by: University of Padova BIRD175145/17 (G.P.), European Research Council CoG project 614750 NOFEAR (G.D.T. and E.S.), and NSERC Discovery Grant 2018–06023 (A.Cam.). The authors thank Leonardo Tauro (University of Padova) for thin section preparation. The authors acknowledge two anonymous reviewers and the Editor Fabrizio Agosta for their constructive comments.
Beschreibung:
Published
Beschreibung:
104328
Beschreibung:
3T. Fisica dei terremoti e Sorgente Sismica
Beschreibung:
JCR Journal
Repository-Name:
Istituto Nazionale di Geofisica e Vulcanologia (INGV)
Materialart:
article
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