By using recently determined experimental phase equilibria we show that the viscosity of granitic magmas emplaced atupper crustal levels is approximately constant a -• 104.5 Pa s, irrespective of their temperature and level of emplacement. Magmas crystallizing as granitic plutons are not water-poor and thus not more viscous than their extrusive equivalents. Instead, comparison between pre-erupt...

There is overwhelming and incontrovertible petrological and geophysical evidence for the significant role played by mantle-derived mafic magma in the generation and growth of continental crust. Likewise, intrusion of mafic magmas beneath or into continental crust is very likely the major source of enthalpy that drives intracrustal differentiation. A simple dynamical model has been constructed t...

S U M M A R Y The migration and accumulation of magma beneath volcanoes often causes surface displacements that can be measured by geodetic techniques. Usually, deformation signals are explained using models with uniform mechanical properties. In this paper, we study surface displacements due to magma chamber inflation, using heterogeneous finite element models. We first present a systematic an...

The Hapaimamo flow contains xenoliths of gabbronorites, troctolites, dunites, websterites and periodotites. Composition of cumulate olivines ranges from Fo78-86, clinopyroxenes ranges from En47-53Wo37-40Fs8-12, and orthopyroxenes ranges from En71-83Wo2-5Fs13-25. Most xenoliths display an intergranular, subpoikilitic or poikilitic texture. Petrologic and compositional information point towards a...

One of the greatest remaining problems in modern volcanology is the process by which volcanic eruptions are triggered. It is generally accepted that eruptions are preceded by magma intrusion [Sigurdsson and Sparks, 1978]. The degree of interaction between previously ponded magma in a chamber and newly intruded magma determines the nature and rate of eruption and also the chemistry of erupted la...

Intrusions of magma induce thermal aureoles in the country rock. Analytical solutions predict that the thickness of an aureole is proportional to the thickness of the intrusion. However, in the field, thermal aureoles are often significantly thinner or wider than predicted by simple thermal models. Numerical models show that thermal aureoles are wider if the heat transfer in the magma is faster...

[1] Volcanic eruptions are often accompanied by spatiotemporal migration of ground deformation, a consequence of pressure changes within magma reservoirs and pathways. We modeled the propagation of pressure variations through the east rift zone (ERZ) of K ılauea Volcano, Hawai‘i, caused by magma withdrawal during the early eruptive episodes (1983–1985) of the ongoing Pu‘u ‘ O‘ o-Kupaianaha erup...

The emplacement of the Mesoproterozoic Götemar Pluton into Paleoproterozoic granitoid host rocks of the Transscandinavian Igneous Belt is re-examined by microfabric analysis, including cathodoluminescence microscopy. Field data on the pluton-host rock system are used to strengthen the model. The Götemar Pluton, situated on the Baltic Shield of SE Sweden, is a horizontally zoned tabular structur...

The Moon was thought to be anhydrous since the Apollo era1, but this view has been challenged by detections of water on the lunar surface2–4 and in volcanic rocks5–9 and regolith10. Part of this water is thought to have been brought through solarwind implantation2–4,7,10 and meteorite impacts2,3,7,11, long after the primary lunar crust formed from the cooling magma ocean12,13. Here we show that...

The Campanian Ignimbrite is a 4200 km trachyte^phonolite pyroclastic deposit that erupted at 39 3 0 1ka within the Campi Flegrei west of Naples, Italy. Here we test the hypothesis that Campanian Ignimbrite magma was derived by isobaric crystal fractionation of a parental basaltic trachyandesitic melt that reacted and came into local equilibrium with small amounts (5^10 wt%) of crustal rock (ska...