Role of large flank-collapse events on magma evolution of volcanoes. Insights from the Lesser Antilles Arc

详细信息    查看全文

• 作者：Georges Boudon ; Beno?t Villemant ; Anne Le Friant ; Martine Paterne ; Elsa Cortijo
• 关键词：Flank-collapse ; Magma evolution ; Lesser Antilles Arc ; Threshold effect ; Magma plumbing system
• 刊名：Journal of Volcanology and Geothermal Research
• 出版年：2013
• 出版时间：1 August, 2013
• 年：2013
• 卷：263
• 期：Complete
• 页码：224-237
• 全文大小：2023 K

文摘

Flank-collapse events are now recognized as common processes of destruction of volcanoes. They may occur several times on a volcanic edifice pulling out varying volumes of material from km³ to thousands of km³. In the Lesser Antilles Arc, a large number of flank-collapse events were identified. Here, we show that some of the largest events are correlated to significant variations in erupted magma compositions and eruptive styles.

On Montagne Pel¨¦e (Martinique), magma production rate has been sustained during several thousand years following a 32 ka old flank-collapse event. Basic and dense magmas were emitted through open-vent eruptions that generated abundant scoria flows while significantly more acidic magmas were produced before the flank collapse. The rapid building of a new cone increased the load on magma bodies at depth and the density threshold. Magma production rate decreased and composition of the erupted products changed to more acidic compared to the preceding period of activity. These low density magma generated plinian and dome-forming eruptions up to the Present. In contrast at Soufri¨¨re Volcanic Centre of St. Lucia and at Pitons du Carbet in Martinique, the flank-collapses have an opposite effect: in both cases, the acidic magmas erupted immediately after the flank-collapses. These magmas are highly porphyritic (up to 60 % phenocrysts) and much more viscous than the magmas erupted before the flank-collapses. They have been generally emplaced as voluminous and uptight lava domes (called ¡°the Pitons¡±). Such magmas could not ascent without a significant decrease of the threshold effect produced by the volcanic edifice loading before the flank-collapse.