Problems in Determining Mantle Geotherms from Pyroxene Compositions of Ultramafic Rocks

摘要: The interpretation of lithologically complex rock sections from xenolith suites sampled by volcanic vents has been recognized as a major problem for some time. recent use inherent pyroxene thermometers and barometers to determine the apparent stratigraphic succession mixed ultramafic xenoliths led conclusions far-reaching importance concerning history lithosphere, technique extended massifs well. While thermometer-barometer approach promises become powerful tool in study many mantle-derived rocks, we have encountered several problems its application that require consideration. These are: (1) systematic compositional variations across contain both dikes their wall rocks yield enormous pressure differences same hand sample, (2) alpine peridotites show ranges far excess those appropriate thickness, (3) fr...