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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 ( |
