نتایج جستجو برای: source of magma
تعداد نتایج: 21186166 فیلتر نتایج به سال:
The first direct evidence that patterns of basaltic eruptive activity may be very similar on Io and Earth was seen on 26 November 1999, when the Solid State Imaging System on board the Galileo spacecraft obtained high-resolution images of a fissure eruption taking place in one of the calderas of the Tvashtar Catena complex. We analyzed the dynamics of the fissure eruption from the morphology of...
This chapter presents the various mechanisms and processes that come into play within the volcanic conduit for a broad range of effusive and dry explosive volcanic eruptions. Decompression during magma ascent causes volatiles to exsolve and form bubbles containing a supercritical fluid phase. Viscous magmas, such as rhyolite or crystal-rich magmas, do not allow bubbles to ascend buoyantly and m...
pleistocene basaltic lava flows, consisting of trachybasalt and basaltic trachyandesite, cover an area north-northwest of shahre-babak in southeastern iran. the whole rock chemistry indicates that the lavas are dominantly alkaline and mildly calc-alkaline. variation diagrams of sio2 with major and trace elements are consistent with fractional crystallization processes involving olivine, pyroxen...
The Bayazeh ophiolite, with Paleozoic age, is located in the eastern margin of the Yazd Block (Central Iran). This ophiolite consists of serpentinized peridotites, metagabbro, ultrabasic metamorphosed dikes, metapicrite, serpentinite and metalistvenite. Rock forming minerals of the metapicrites in the Bayazeh ophiolite are olivine (completely altered to serpentine), clinopyroxene (diopside, aug...
Eruptive sequences can be used as windows into the thermal and chemical evolution of magma chambers. We examined a continuous vertical section of the Baichahe basalt flow associated with the late Cenozoic Chifeng flood basalt in Inner Mongolia, North China. From oldest to youngest, MgO increases, K2O, light rare earths and other incompatible elements decrease, and Nb/La and radiogenic Pb isotop...
The Plio–Quaternary volcanic eruptions have made basaltic lavas in NW Iran and Azerbaijan. Basaltic lavas with prismatic structure cover the Plio-Pliostocene volcano-sedimentary or Quaternary alluviums. The studied regions are situated in Azerbaijan provinces in areas of Monnavar, Herris, Ahar, Kaleibar, Mahabad, Salmas, Maku, Marand, Sarab and Zunuz. The studied sample rocks are olivine basalt...
Orientation of the eruption fissures and composition of the lavas of the Miyakejima volcano is indicative of the competitive processes of the regional tectonic stress and the local stress generated by the activity of a magma plumbing system beneath the volcano. We examined the distributions and magmatic compositions of 23 fissures that formed within the last 2800 years, based on a field survey ...
A method is proposed to invert displacement and tilt measurements from a single monitoring location to constrain the nature of a volcanic pressure source. Evolutionary strategy is applied to a sequence of Mogi solutions and the program is shown capable of distinguishing between depth and volume increment of the magma source, in addition to its 3-dimensional spatial coordinates. The mechanism is...
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