نتایج جستجو برای: acidic magma

تعداد نتایج: 41771  

Abedini, Ali, Alipour, Samad, Khalilzadeh, Hadi,

Niaz area is located at the Alborz-Azarbaijan magmatic zone in the northwest of Iran. All of the rock units in this area are composed of intermediate to acidic igneous rocks of Oligocene to Miocene age. Based on geochemical data, the mineralized monzonitic rocks in this area belong to high-K calc-alkaline and shoshonitic magma series, has a metalauminous to slightly peraluminous nature and belo...

A. Moradian H. Ahmadipour J. F. Santos M. Noorizadeh M. R. Ghassemi

The Hezar Igneous Complex (HIC) in the south-eastern part of Urumieh-Dokhtar magmatic arc, is the most prominent magmatic feature in the Kerman Porphyry Copper Belt, that understanding magmatic evolution of which may shed light on the tectonomagmatic development of this less-studied part of an important magmatic arc in the Neotethys realm. The HIC has been developed in the the intersection of t...

پایان نامه :وزارت علوم، تحقیقات و فناوری - دانشگاه شهید باهنر کرمان 1386

چکیده ندارد.

Journal: :زمین شناسی اقتصادی 0
محمد سیاری مرتضی شریفی جمشید احمدیان

volcanic rocks of interest are situated in the middle part of the urumieh-dokhtar magmatic arc (udma). they are parts of a vast magmatic province located in the north of bitlis-zagros suture zone. having a prevailing porphyritic texture, these rocks include phenocrysts of plagioclase, amphibole and biotite in a matrix composed of feldspar, quartz, opaque, glass and microlite and mineralogically...

2014
Hiroyuki K. M. Tanaka Taro Kusagaya Hiroshi Shinohara

Radiographic imaging of magma dynamics in a volcanic conduit provides detailed information about ascent and descent of magma, the magma flow rate, the conduit diameter and inflation and deflation of magma due to volatile expansion and release. Here we report the first radiographic observation of the ascent and descent of magma along a conduit utilizing atmospheric (cosmic ray) muons (muography)...

2016
Sofia De Gregorio Marco Camarda

In open conduit volcanoes, volatile-rich magma continuously enters into the feeding system nevertheless the eruptive activity occurs intermittently. From a practical perspective, the continuous steady input of magma in the feeding system is not able to produce eruptive events alone, but rather surplus of magma inputs are required to trigger the eruptive activity. The greater the amount of surpl...

2013
Mark Jellinek Donald J. DePaolo

The relatively low rates of magma production in island arcs and continental extensional settings require that the volume of silicic magma involved in large catastrophic caldera-forming (CCF) eruptions must accumulate over periods of 105 to 106 years. We address the question of why buoyant and otherwise eruptible highsilica magma should accumulate for long times in shallow chambers rather than e...

2004
Frank J. Spera

Kinetic and fluid dynamic constraints on deepseated magma migration rates suggest ascent velocities in the range 10 to 30 m/s, 10 -1 to 10m/s and 10 -2 to 5m/s for kimberlitic, garnet peridotite-bearing and spinel peridotite-bearing alkalic magmas. These rates virtually demand translithospheric magma transport by a fracture as opposed to diapiric mechanism. The hypothesis that volatile exsoluti...

Journal: :Science 1999
Wylie Voight Whitehead

Volatiles dissolved in silicic magma at depth exsolve as the magma nears the surface and cause an increase in viscosity of the magma. A model of a volcanic conduit within an elastic medium and a viscosity dependent on the volatile content of the magma produces oscillatory magma flow for a critical range of steady input flow rates. Oscillatory flow is recognized as a fundamental mode of behavior...

2016
Harri Geiger Abigail K. Barker Valentin R. Troll

Mt. Cameroon is one of the most active volcanoes in Africa and poses a possible threat to about half a million people in the area, yet knowledge of the volcano's underlying magma supply system is sparse. To characterize Mt. Cameroon's magma plumbing system, we employed mineral-melt equilibrium thermobarometry on the products of the volcano's two most recent eruptions of 1999 and 2000. Our resul...

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