Petrology of the 1998-2000 products of Volcan de Colima, Mexico.
Mora, J C; Macias, J L; Saucedo, R; Orlando, A; Manetti, P; Vaselli, O (2002) Petrology of the 1998-2000 products of Volcan de Colima, Mexico. Journal of Volcanology and Geothermal Research. 117; 1-2, Pages 195-212. 2002.
| Authors | Mora, J C; Macias, J L; Saucedo, R; Orlando, A; Manetti, P; Vaselli, O |
|---|---|
| Year | 2002 |
| Title | Petrology of the 1998-2000 products of Volcan de Colima, Mexico. |
| Source | Journal of Volcanology and Geothermal Research. 117; 1-2, Pages 195-212. 2002. |
| Publisher | Elsevier. Amsterdam, Netherlands. 2002. |
| Document type | Serial |
| ISSN | 0377-0273 |
| GeoRef | 2002-081838 |
| Keywords | andesites-; chain-silicates; chemical-composition; Colima-; feldspar-group; framework-silicates; fugacity-; glasses-; igneous-rocks; iron-oxides; Jalisco-Mexico; lava-flows; magmas-; metals-; Mexico-; oxides-; oxygen-; petrography-; plagioclase-; pyroxene-group; rare-earths; silicates-; titanium-oxides; volcanic-rocks; volcanism-; volcanoes-; water-content; whole-rock |
| DOI | 10.1016/S0377-0273(02)00244-5 |
Abstract
The 1998-2000 activity of Volcan de Colima generated a series of lava flows and block-and-ash flows of andesitic composition 59-61% SiO sub 2 . Juvenile clasts from both lava flows and pyroclastic deposits contain phenocrysts of plagioclase>two pyroxenes>Fe-Ti oxides and rare amphibole set in a groundmass of the same minerals and rhyolitic glass 74-77% SiO sub 2 . Prior to the eruption, the andesitic magma was stored at a temperature of approximately 900 degrees C based on titanomagnetite-ilmenite equilibrium. The magma had an oxygen fugacity of 10 super -11.1 , corresponding to 0.8 log units above the NNO oxygen buffer, and water contents in the rhyolitic melt of approximately 2 wt%, suggesting that the magma was water-undersaturated at depth. The presence of amphibole with clear signs of disequilibrium, quartz xenocrysts, and plagioclase An sub <50 as inclusions in pyroxenes and phenocryst cores suggests that the magma chamber was first occupied by an andesitic magma at temperatures <900 degrees C and probably as low as 840 degrees C. The presence of plagioclase phenocrysts with reverse zoning rims, An sub >50 and microphenocrysts An sub >50 indicate the injection of a new hotter and more mafic andesite into the magma chamber. This process was the main trigger of the 1998-2000 activity.