Original paper

A pressure-temperature-time path for the NE Mont-Blanc massif: Fluid-inclusion, isotopic and thermobarometric evidence

Marshall, Daniel; Pfeifer, Hans-Rudolf; Hunziker, Johannes C.; Kirschner, David

European Journal of Mineralogy Volume 10 Number 6 (1998), p. 1227 - 1240

44 references

published: Dec 1, 1998
manuscript accepted: May 27, 1998
manuscript received: Feb 27, 1998

DOI: 10.1127/ejm/10/6/1227

BibTeX file

ArtNo. ESP147051006022, Price: 29.00 €

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Abstract The Mont-Chemin region at the NE extreme of the Mont-Blanc massif, Canton Valais, Switzerland is predominantly comprised of the granitic rocks of the Mont-Blanc intrusive rock suite and the Mont-Blanc basement gneisses. Fluid inclusions, fluid-mineral equilibria, stable-isotope and radiogenic-isotope studies have been used to derive pressure, temperature, age (PTt) and fluid-composition constraints for a number of Alpine events. The earliest of these events is recorded in a paragonite-katophorite schist hosted within the basement gneisses. The paragonites yield a 40Ar/39Ar age of 47 Ma. Mineral thermobarometry is consistent with formation temperatures in excess of 300°C, with minimum pressures of 1500 bars. A well-defined pressure-temperature uplift path is recorded in minerals hosted by veins of different generations. The overall PTt path defines a geothermal gradient of 25°C/km, but the younger portions of this PTt path are consistent with geothermal gradients slightly in excess of 50°C/km, similar to those observed to the East along the Rhône-Simplon line


Alpine pressure-temperature-time pathsfluid inclusionsthermobarometry40Ar/39Ar dating