Article ID | Journal | Published Year | Pages | File Type |
---|---|---|---|---|
6440532 | Lithos | 2016 | 49 Pages |
Abstract
Significant compositional differences were found between (1) the older (>Â 13Â Ma) large-volume plateau-forming ignimbrites in northernmost Chile and southern Peru and (2) the younger (<Â 10Â Ma) Altiplano-Puna-Volcanic-Complex (APVC) ignimbrites that are of similar volumes. Older ignimbrites are less depleted in HREE and less radiogenic in Sr isotopes, indicating smaller crustal contributions during evolution in a thinner and thermally less evolved crust. These compositional variations indicate a relation to crustal thickening with a “transition” from plagioclase to amphibole and garnet residual mineralogy between 13 and 9Â Ma. Compositional and volumetric variations correlate to the N-S passage of the Juan-Fernandéz-Ridge, crustal shortening and thickening, and increased average crustal temperatures during the past 26Â Ma.
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Authors
M. Brandmeier, G. Wörner,