• journal_title：American Mineralogist
• Contributor：Fabrizio Nestola ; Silvia Mittempergher ; Giulio Di Toro ; Federico Zorzi ; Danilo Pedron
• Publisher：Mineralogical Society of America
• Date：2010-
• Format：text/html
• Language：en
• Identifier：10.2138/am.2010.3393
• journal_abbrev：American Mineralogist
• issn：0003-004X
• volume：95
• issue：2-3
• firstpage：405
• section：Articles

The determination of the maximum temperature achieved by friction melt (T_melt) in pseudotachylyte-bearing faults is crucial to estimate earthquake source parameters (e.g., earthquake energy budgets, coseismic fault strength) on a geological basis. Here we investigated the mineralogy of a pseudotachylyte from the Gole Larghe Fault (Italian Alps) by using X-ray powder diffraction, micro-Raman spectroscopy, and EDS-equipped field emission scanning electron microscopy. In particular, we report the presence of the hexagonal polymorph of CaAl₂Si₂O₈ (dmisteinbergite) in a pseudotachylyte. Published experimental work shows dmisteinbergite can crystallize at 1200–1400 °C by rapid quenching. Therefore, the presence of dmisteinbergite in pseudotachylyte could be a reliable geothermometer for friction melts for which T_melt has only as yet been estimated.