Miguel A. Parada (coordinator), Leopoldo López-Escobar, Verónica Oliveros, Francisco Fuentes, Diego Morata, Mauricio Calderón, Luis Aguirre, Gilbert Féraud, Felipe Espinoza, Hugo Moreno, Oscar Figueroa, Jorge Muñoz Bravo, Rosa Troncoso Vásquez, Charles R. Stern, 2007. "Andean magmatism", The Geology of Chile, Teresa Moreno, Wes Gibbons
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Magmatism in the Chilean Andes has taken place since about 300 Ma as a consequence of protracted subduction, although with significant spatial and temporal variations due to changes in ocean-floor geodynamics controlling distinct large-scale magmatic events. Early subduction along the Chilean segment of the Gondwana active margin took place during Late Palaeozoic times and generated typical arc magmatism and a subduction complex in the forearc environment. This tectonomagmatic regime was interrupted by mid-Permian contractional tectonics (collisional?) giving rise to a thickening of the crust that allowed deep crustal melt generation. Following this the entire Mesozoic history of the area became dominated by subduction-related extensional tectonics with mostly bimodal magmatism reflecting the involvement, to different degrees, of both crust and mantle as magma sources. Mesozoic volcanism and plutonism appear to have been independent of each other. Subsequent Cenozoic magmatism records changing geodynamic conditions from Palaeogene–early Neogene extension to late Neogene compression. The Neogene magmatic episodes are interpreted as an indirect consequence of oceanic ridge subduction: the Juan Fernández Ridge along the north-central Chilean margin, and the Chile Ridge along the southernmost Chilean border. Modern volcanism is also influenced by these ridge subductions, either by generating gaps in the Quaternary volcanic chain, or adakitic volcanism derived from slab melting.
Despite the essentially tectonic control outlined above, this chapter is subdivided geographically into four Andean segments, each of which exhibits distinct magmatic features. These segments are: 18–28°S, 28–38°S, 40–47°S and 47–55°S. The exception to this approach is the section on Quaternary volcanism, which
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This book is the first comprehensive account in English of the geology of Chile, providing a key reference work that brings together many years of research, and written mostly by Chilean authors from various universities and other centres of research excellence. The 13 chapters begin with a general overview, followed by detailed accounts of Andean tectonostratigraphy and magmatism, the amazingly active volcanism, the world class ore deposits that have proven to be so critical to the welfare of the country, and Chilean water resources. The subject then turns to geophysics with an examination of neotectonics and earthquakes, the hazardous frequency of which is a daily fact of life for the Chilean population. There are chapters on the offshore geology and oceanography of the SE Pacific Ocean, subjects that continue to attract much research not least from those seeking to understand world climatic variations, and on late Quaternary land environments, concluding with an account examining human colonization of southernmost America.
During his voyage on H.M.S. Beagle, an extended visit to Chile (1834-35) had a profound impact on Charles Darwin, especially on his understanding of volcanoes, earthquakes and tsunamis. Over more recent decades scientists have come to recognize the Chilean Andes as providing the classic example of a mountain belt produced by oceanic subduction beneath a continent, as well as some of the most dramatic scenic and climatic variations on Earth. In the final chapter, the editors offer a description of a drive from the Mediterranean landscapes of central Chile to the hyperarid Atacama Desert, a contribution designed to give visitors a chance to experience for themselves the geology and scenery of this extraordinary country.