The origin and emplacement of Domo Tinto, Guallatiri volcano, Northern Chile
Guallatiri Volcano (18°25'S, 69°05'W) is a large edifice located on the Chilean Altiplano near the Bolivia/Chile border. This Pleistocene-Holocene construct, situated at the southern end of the Nevados de Quimsachata chain, is an andesitic/dacitic complex formed of early stage lava flows a...
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| Autores principales: | , , |
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| Lenguaje: | English |
| Publicado: |
Servicio Nacional de Geología y Minería (SERNAGEOMIN)
2014
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| Materias: | |
| Acceso en línea: | http://www.scielo.cl/scielo.php?script=sci_arttext&pid=S0718-71062014000300004 |
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| Sumario: | Guallatiri Volcano (18°25'S, 69°05'W) is a large edifice located on the Chilean Altiplano near the Bolivia/Chile border. This Pleistocene-Holocene construct, situated at the southern end of the Nevados de Quimsachata chain, is an andesitic/dacitic complex formed of early stage lava flows and later stage coulées and lava domes. Domo Tinto (5±3 ka, recent 40Ar/39Ar date) is a small dome located on the southern flanks of Guallatiri Volcano. It is composed of monotonous, crystal-rich andesite (~62% SiO2) with predominant plagioclase, amphibole, biotite and rare clinopyroxene within a glassy groundmass containing plagioclase and subordinate amphibole microlites. Geochemical data indicate the Tinto lava is compositionally homogeneous. The occurrence of ovoid magmatic inclusions of basaltic andesite (<0.5% volume) and ubiquitous disequilibrium features in the mineral assemblage indicate that the magma chamber was perturbed by repeated intrusions of mafic magma. These events promoted magma-mingling, inclusion disaggregation and convective self-mixing before a critical recharge event triggered eruption and formation of the dome. Glacially eroded sections through Domo Tinto indicate that it was formed by the sequential extrusion of several hummocky lobes with a sub-horizontal base and a convex-upward upper surface. Each lobe exhibits a thin, basal zone of foliated lava and a thick interior of massive lava (up to ~20 m thick) and these lobes have piled atop each other to form an overall pancake morphology. The lack of any associated explosive material and collapse-scar features indicate the formation of Domo Tinto was relatively benign. |
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