A suite of eight unshocked equilibrated H-chondrites ranging from petrographic type 4 to 6 (La Villa, Raguli, FRO 90076, Miami, FRO 90049, Estacado, FRO 90156 and Acfer 314) was selected for a systematic study of orthopyroxene cation ordering temperatures. The closure temperatures of the Fe-Mg exchange lie within the 384 +/- 48 degrees C to 480 +/- 28 degrees C range, regardless of the petrographic type. Data suggests that metamorphosed H-chondrites share a similar thermal evolution close to 380-480 degrees C. Indeed, this indicates that H4, H5 and H6 chondrites were located in petrogenetic environments characterized by similar temperature-time conditions when cooling through the above temperature interval.
|Autori:||Folco L; Mellini M; Pillinger C T|
|Titolo:||Unshocked equilibrated H-chondrites: a common low-temperature record from orthopyroxene iron-magnesium ordering|
|Anno del prodotto:||1996|
|Appare nelle tipologie:||1.1 Articolo in rivista|