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 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...

The mechanical conditions for a volcanic eruption to occur are conceptually simple: a magma-driven fracture (normally a dyke) must be able to propagate from the source to the surface. The mechanics of small to moderate (eruptive volumes less than 10 km 3 ) is reasonably well understood, whereas that of large eruptions (eruptive volumes of 10-1000 km 3 ) is poorly understood. Here I propose that...

For those who remember the classic disaster-docudrama Supervolcano (BBC-Discovery Channel 2005), the adjective “eruptible” is likely to ring a bell. Set in the near future and generally quite scientifically literate, the movie envisions volcanologists trying desperately to evaluate the near-term threat posed by the giant Yellowstone magmatic system. At the heart of their mission, and of the dra...

the miocene pyroxene andesite lava flows are exposed in southeastern edge of urumieh dokhtar magmatic assemblage in iran. the hypocrystalline andesite in parts contain conspicuous co-magmatic igneous enclaves which are dark grey and occur mostly as spherical and occasionally as ribbon shapes with some showing chilled margins. petrographic study shows that the ribbon type enclaves have been form...

Crustal stress field can have a significant influence on the way magma is channeled through the crust and erupted explosively at the surface. Large Caldera Forming Eruptions (LCFEs) can erupt hundreds to thousands of cubic kilometers of magma in a relatively short time along fissures under the control of a far-field extensional stress. The associated eruption intensities are estimated in the ra...

Deep long-period events (DLP events) or deep low-frequency earthquakes (deep LFEs) are deep earthquakes that radiate low-frequency seismic waves. While tectonic deep LFEs on plate boundaries are thought to be slip events, there have only been a limited number of studies on the physical mechanism of volcanic DLP events around the Moho (crust-mantle boundary) beneath volcanoes. One reasonable mec...

We present results from a numerical conduit model of nonequilibrium magma degassing. We show that CO2 /H2O concentration ratios in pyroclastic obsidian from the ca. 1340 A.D. Mono Craters eruption may record nonequilibrium degassing during magma ascent. Our results also indicate that permeability-controlled, open-system gas loss is consistent with obsidian formation and promotes nonequilibrium ...

Large-volume caldera-forming eruptions of silicic magmas are an important feature of continental volcanism. The timescales and mechanisms of assembly of the magma reservoirs that feed such eruptions as well as the durations and physical conditions of upper-crustal storage remain highly debated topics in volcanology. Here we explore a comprehensive data set of isotopic (O, Hf) and chemical proxi...

How much magma needs to be added to a shallow magma chamber to cause rupture, dyke injection, and a potential eruption? Models that yield reliable answers to this question are needed in order to facilitate eruption forecasting. Development of a long-lived shallow magma chamber requires periodic influx of magmas from a parental body at depth. This redistribution process does not necessarily caus...