Effusive eruptions from a large silicic magma chamber: the Bearhead Rhyolite, Jemez volcanic field, NM

The Kos–Nisyros–Yali volcanic field has produced a range of volcanic products over the last 3 million years. Volumetrically, silicic magma dominates, and activity includes one of the largest known explosive eruptions of the Aegean arc, the >60 km3 (dense-rock equivalent), 161 ka rhyolitic Kos Plateau Tuff. The Kos–Nisyros–Yali volcanic field is situated within an area of active crustal extension, which has greatly influenced magmatic processes and landscape development in the region. Recent seismic unrest, surface deformation and intense geothermal activity indicate that the system remains active, particularly around the Nisyros and Yali edifices. These signs of magmatic activity, together with the fact that the most recent eruptions have become increasingly silicic, would justify detailed monitoring of the area.

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Rapid pre-eruptive thermal rejuvenation in a large silicic magma body: the case of the Masonic Park Tuff, Southern Rocky Mountain volcanic field, CO, USA

Contributions to Mineralogy and Petrology ◽

10.1007/s00410-017-1351-3 ◽

2017 ◽

Vol 172 (5) ◽

Cited By ~ 13

Author(s):

J. T. Sliwinski ◽

O. Bachmann ◽

M. A. Dungan ◽

C. Huber ◽

C. D. Deering ◽

...

Keyword(s):

Rocky Mountain ◽

Volcanic Field ◽

Silicic Magma ◽

Magma Body ◽

Southern Rocky Mountain

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40Ar/39Ar laser probe ages of Bishop Tuff quartz phenocrysts substantiate long-lived silicic magma chamber at Long Valley, United States

Geology ◽

10.1130/0091-7613(1995)023<0759:aalpao>2.3.co;2 ◽

1995 ◽

Vol 23 (8) ◽

pp. 759 ◽

Cited By ~ 57

Author(s):

Paul van den Bogaard ◽

Carsten Schirnick

Keyword(s):

United States ◽

Magma Chamber ◽

Silicic Magma ◽

Bishop Tuff ◽

Laser Probe ◽

Long Valley

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Thermal evolution of silicic magma chambers after basalt replenishments

Earth and Environmental Science Transactions of the Royal Society of Edinburgh ◽

10.1017/s0263593300007288 ◽

2000 ◽

Vol 91 (1-2) ◽

pp. 47-60 ◽

Cited By ~ 22

Author(s):

Takehiro Koyaguchi ◽

Katsuya Kaneko

Keyword(s):

Magma Chamber ◽

Thermal Evolution ◽

Bulk Composition ◽

Thermal Fluctuations ◽

Silicic Magma ◽

Magma Chambers ◽

Solid States ◽

Liquid Part ◽

Two Stages

In order to understand the governing factors of petrological features of erupted magmas of island-arc or continental volcanoes, thermal fluctuations of subvolcanic silicic magma chambers caused by intermittent basalt replenishments are investigated from the theoretical viewpoint. When basaltic magmas are repeatedly emplaced into continental crust, a long-lived silicic magma chamber may form. A silicic magma chamber within surrounding crust is composed of crystal-melt mixtures with variable melt fractions. We define the region which behaves as a liquid in a mechanical sense (‘liquid part’) and the region which is in the critical state between liquid and solid states (‘mush’) collectively as a magma chamber in this study. Such a magma chamber is surrounded by partially molten solid with lower melt fractions. Erupted magmas are considered to be derived from the liquid part. The size of a silicic magma chamber is determined by the long-term balance between heat supply from basalt and heat loss by conduction, while the temperature and the volume of the liquid part fluctuate in response to individual basalt inputs. Thermal evolution of a silicic magma chamber after each basalt input is divided into two stages. In the first stage, the liquid part rapidly propagates within the magma chamber by melting the silicic mush, and its temperature rises above and decays back to the effective fusion temperature of the crystal-melt mixture on a short timescale. In some cases the liquid part no longer exists. In the second stage, the liquid part ceases to propagate and cools slowly by heat conduction on a much longer timescale. The petrological features of the liquid part, such as the amount of unmelted preexisting crystals, depend on the intensity of individual pulses of the basalt heat source and the degree of fractionation during the first stage, as well as the bulk composition of the silicic magma.

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