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Epithermal Gold 2012
Epithermal Gold Deposits of the Western Pacific
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[Aso Volcano]
Kyushu Field Workshop - Aso Volcano:   The second day of the field workshop was focussed on the Aso volcano, caldera and giant volcanic edifice that forms the core of the island of Kyushu and is located to the south of Kuju.   This volcanic complex comprises a large 15 x 20 km caldera (the lower left image is a view north from the southern rim, across the bed of the drained southern half of the caldera lake, now intensively farmed), and the central chain of andesitic, dacitic and lesser rhyolitic cones that form the ridge in the distance, stretching east-west across the caldera.   The lower right image is within the cone complex and looks towards the current main geothermally active crater which is subject to sporadic volcanic eruption.   The upper image is of the main crater, currently occupied by a lake.   Two plumes of vapour can be seen emanating from the crater, one to the left which is steam from the heated lake, the other to the right, tinged blue by magmatic SO2, released from a fault zone on the margin of the crater.   The hydrothermal fluids circulated through the volcanic complex are both meteoric, collected in the crater lake and caldera, and magmatic from the deep igneous heat source.   Photographs by Mike Porter.

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