Contact: Christa Stratton
Geological Society of America
Caption: This is El Misti Volcano in Peru. An article by Mirian Mamani et al. in the December 2009 issue of Geology examines the Central Andes of Northern Chile and Southern Peru which have been characterized over the past 20 million years by a series of zones where magmas have formed and ascended through the crust. Many so called "intrusions" and volcanic centers are associated with ore deposits (gold, silver, copper). Mamani et al. combine a large number of new major and trace element analyses and (Pb-Sr-Nd) isotopes and geochemical analyses (n = 420) with a compilation of published data (total 1635) to trace the systematic changes in magma composition through time and space. Based on this, the authors relate the compositional changes in the magmas to the tectonic evolution of the active Andean continental margin and the increasing thickness of the crust during the formation of the present Andes during the last 35 million years.
Credit: Mirian Mamani et al., Geology, Vol. 37, No. 11, p. 162-182.
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Related news release: January-February 2010 GSA Bulletin highlights