Monte Amiata is a volcano characterized by acidic effusive products, emitted between 304 - 230 ka. The peculiar textural and petrographic features together with the uncommon length of the lava flows erupted at Monte Amiata have stimulated our interest and raised the following questions: "What were the temperatures and viscosities which brought to the eruption of those extraordinarily crystal-rich magmas and to the emplacement of those up to 8 km long and on average 30 m thick lava flows and exogenous lava domes at Monte Amiata?" In order to answer these questions, we, firstly, estimated, by the use of the most recent geo-thermometric tools, the temperatures representative of the storage, ascent, and emplacement of the magmatic and volcanic mixtures. Later, we used the obtained temperature values to estimate the crystalbearing viscosity of the volcanic mixtures governing the emplacement of lava flows at Monte Amiata. Our results revealed that responsible of the emplacement of the above-mentioned lavas was, likely, a combination of the anomalously high eruptive temperature and the large volume of the erupted products. These conditions favoured the maintaining of the emplacement temperature well above the limit temperature for viscous flow, i.e. the glass transition, for a time long enough (e.g. years) to allow, also at their relatively high viscosities, to flow the observed lengths.Monte Amiata is a volcano characterized by acidic effusive products, emitted between 304 - 230 ka. The peculiar textural and petrographic features together with the uncommon length of the lava flows erupted at Monte Amiata have stimulated our interest and raised the following questions: "What were the temperatures and viscosities which brought to the eruption of those extraordinarily crystal-rich magmas and to the emplacement of those up to 8 km long and on average 30 m thick lava flows and exogenous lava domes at Monte Amiata?" In order to answer these questions, we, firstly, estimated, by the use of the most recent geo-thermometric tools, the temperatures representative of the storage, ascent, and emplacement of the magmatic and volcanic mixtures. Later, we used the obtained temperature values to estimate the crystalbearing viscosity of the volcanic mixtures governing the emplacement of lava flows at Monte Amiata. Our results revealed that responsible of the emplacement of the above-mentioned lavas was, likely, a combination of the anomalously high eruptive temperature and the large volume of the erupted products. These conditions favoured the maintaining of the emplacement temperature well above the limit temperature for viscous flow, i.e. the glass transition, for a time long enough (e.g. years) to allow, also at their relatively high viscosities, to flow the observed lengths.
Il vulcanismo effusivo acido del Monte Amiata: stima delle condizioni pre- e sin-eruttive ed implicazioni vulcanologiche
Giordano D;La Felice S;
2017
Abstract
Monte Amiata is a volcano characterized by acidic effusive products, emitted between 304 - 230 ka. The peculiar textural and petrographic features together with the uncommon length of the lava flows erupted at Monte Amiata have stimulated our interest and raised the following questions: "What were the temperatures and viscosities which brought to the eruption of those extraordinarily crystal-rich magmas and to the emplacement of those up to 8 km long and on average 30 m thick lava flows and exogenous lava domes at Monte Amiata?" In order to answer these questions, we, firstly, estimated, by the use of the most recent geo-thermometric tools, the temperatures representative of the storage, ascent, and emplacement of the magmatic and volcanic mixtures. Later, we used the obtained temperature values to estimate the crystalbearing viscosity of the volcanic mixtures governing the emplacement of lava flows at Monte Amiata. Our results revealed that responsible of the emplacement of the above-mentioned lavas was, likely, a combination of the anomalously high eruptive temperature and the large volume of the erupted products. These conditions favoured the maintaining of the emplacement temperature well above the limit temperature for viscous flow, i.e. the glass transition, for a time long enough (e.g. years) to allow, also at their relatively high viscosities, to flow the observed lengths.Monte Amiata is a volcano characterized by acidic effusive products, emitted between 304 - 230 ka. The peculiar textural and petrographic features together with the uncommon length of the lava flows erupted at Monte Amiata have stimulated our interest and raised the following questions: "What were the temperatures and viscosities which brought to the eruption of those extraordinarily crystal-rich magmas and to the emplacement of those up to 8 km long and on average 30 m thick lava flows and exogenous lava domes at Monte Amiata?" In order to answer these questions, we, firstly, estimated, by the use of the most recent geo-thermometric tools, the temperatures representative of the storage, ascent, and emplacement of the magmatic and volcanic mixtures. Later, we used the obtained temperature values to estimate the crystalbearing viscosity of the volcanic mixtures governing the emplacement of lava flows at Monte Amiata. Our results revealed that responsible of the emplacement of the above-mentioned lavas was, likely, a combination of the anomalously high eruptive temperature and the large volume of the erupted products. These conditions favoured the maintaining of the emplacement temperature well above the limit temperature for viscous flow, i.e. the glass transition, for a time long enough (e.g. years) to allow, also at their relatively high viscosities, to flow the observed lengths.I documenti in IRIS sono protetti da copyright e tutti i diritti sono riservati, salvo diversa indicazione.
