Institution: | 1 Laboratoire de Pétrologie, Département des Sciences de la Terre, U.A. 726, Université Claude Bernard — Lyon I, 27–43 Boulevard du 11 Novembre, 69622, Villeurbanne Cédex, France 2 Laboratoire de Minéralogie-Cristallographie, U.A. 805, Université Claude Bernard — Lyon I, 27–43 Boulevard du 11 Novembre. 69622, Villeurbanne Cédex, France |
Abstract: | Two Alpine eclogite bodies, sampled in metaophiolitic complexes of the Piemonte Zone, have been studied for geothermometry. It is demonstrated that temperature estimates, by both exchange thermometry and sizes of antiphase domains in omphacites, give rise to erratic results when the defect structures of the minerals are not taken into account. Microstructural criteria, by means of both optical and TEM microscopy, for reliable thermometry in low-temperature eclogites are disscussed. The dynamically recrystallized grains are the more suitable sites for the application of exchange thermometry, while only low-strained omphacites can be used for thermometry based on APD's. |