نتایج جستجو برای: multiple magma source

تعداد نتایج: 1150256  

2004
LORELLA FRANCALANCI GARETH R. DAVIES WIM LUSTENHOUWER SIMONE TOMMASINI PAUL R. D. MASON SANDRO CONTICELLI

Over the last several hundred years, Stromboli has been characterized by steady-state Strombolian activity. The volcanic products are dominated by degassed and highly porphyritic (HP-magma) black scoria bombs, lapilli and lava flows of basaltic shoshonitic composition. Periodically (about one to three events per year), more energetic explosive eruptions also eject light coloured volatile-rich p...

2002
A. Barmin O. Melnik R.S.J. Sparks

Lava dome eruptions commonly display fairly regular alternations between periods of high activity and periods of low or no activity. The time scale for these alternations is typically months to several years. Here we develop a generic model of magma discharge through a conduit from an open-system magma chamber with continuous replenishment. The model takes account of the principal controls on f...

2012
Guilherme A. R. Gualda Ayla S. Pamukcu Mark S. Ghiorso Alfred T. Anderson Stephen R. Sutton Mark L. Rivers

Supereruptions violently transfer huge amounts (100 s-1000 s km(3)) of magma to the surface in a matter of days and testify to the existence of giant pools of magma at depth. The longevity of these giant magma bodies is of significant scientific and societal interest. Radiometric data on whole rocks, glasses, feldspar and zircon crystals have been used to suggest that the Bishop Tuff giant magm...

2018
Tobias Mattsson Steffi Burchardt Bjarne S. G. Almqvist Erika Ronchin

Felsic magma commonly pools within shallow mushroom-shaped magmatic intrusions, so-called laccoliths or cryptodomes, which can cause both explosive eruptions and collapse of the volcanic edifice. Deformation during laccolith emplacement is primarily considered to occur in the host rock. However, shallowly emplaced laccoliths (cryptodomes) show extensive internal deformation. While deformation o...

2018
Lionel Wilson James W. Head

Lunar floor-fractured craters (FFCs) represent the surface manifestation of a class of shallow crustal intrusions in which magma-filled cracks (dikes) rising to the surface from great depth encounter contrasts in host rock lithology (breccia lens, rigid solidified melt sheet) and intrude laterally to form a sill, laccolith or bysmalith, thereby uplifting and deforming the crater floor. Recent d...

2007
R. W. Wichman

Endogenic modification in lunar floor-fractured craters can constrain spatial variations in early lunar conditions. The nature of these constraints, however, depends on the assumed mechanism of crater modification. For viscous relaxation, the extent of crater modification depends on the surrounding crustal viscosity and thus provides loose constraints on the history of crustal heating within a ...

تاکی, سعید,

The Upper Cretaceous volcanic and subvolcanic rocks from the Nageleh Sar, south of Mahmood Abad town in north Iran are dolerite, olivine basalt, trachyandesite and alkali trachyte. These units in an ordered stratification are set in a way that creates a syncline with WNW-ESE axial trend. The chemical data and discrimination diagrams represent medium alkaline bimodal series for the studied sampl...

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