A.L. Grunder Robert E. Drake W. Hildreth 1984 <div id="15238784" class="article-section-wrapper js-article-section js-content-section " data-section-parent-id="0"><p>A 26 × 14-km composite ring-structure caldera of late Pleistocene age has been discovered and mapped near the Andean crest in central Chile (35°30′S). Rhyodacitic to dacitic zoned ash-flow sheets, each representing 150 to 300 km³<span>&nbsp;</span>of magma, were emplaced 0.8, 0.3, and 0.15 m.y. ago; the youngest of the associated collapses was closely followed by resurgent doming of the caldera floor and development of a longitudinal graben. Postcaldera eruptions of dacite and andesite have persisted into Holocene time, and active hot springs are abundant along caldera-marginal and resurgent fault systems, suggesting a significant geothermal-energy resource. The Pleistocene eruption rate of this district and the abundance of older Quaternary to Miocene ash-flow remnants in the 33°S to 36°S segment of the glaciated southern Andes indicate that ash-flow magmatism has been no less important here than in the arid central Andes (16°S–28°S), where ash-flow sheets are far better preserved.</p></div> application/pdf 10.1130/0016-7606(1984)95<45:TLSTAT>2.0.CO;2 en Geological Society of America The Loma Seca tuff and the Calabozos caldera: a major ash-flow and caldera complex in the southern Andes of central Chile article