|
|||||
|
|
Andean subduction-related mantle xenoliths: Isotopic evidence of Sr–Nd decoupling during metasomatism |
|
| Authors: | RV Concei o G Mallmann E Koester M Schilling GW Bertotto and A Rodriguez-Vargas |
| Institution: | aDepartamento de Geologia, Universidade Federal do Rio Grande do Sul, Av. Bento Gonçalves 9500, C.P. 15001, 91501-970, Porto Alegre, RS, Brazil bLaboratório de Geologia Isotópica, CPGq, Universidade Federal do Rio Grande do Sul, CEP 91501970, Porto Alegre, Brazil cPrograma de Pós-graduação em Geociências, CNPq, Universidade Federal do Rio Grande do Sul, CEP 91501970, Porto Alegre, Brazil dFacultad de Ciencias Fisicas y Matematicas, Universidad de Chile, Santiago 4058, Chile eCONICET, Facultad de Ciencias Exactas y Naturales, Universidade Nacional de La Pampa, Santa Rosa 644, Argentina fUniversidad Nacional de Colômbia, 4452 Bogotá, Colombia |
| Abstract: | Sr–Nd isotopic analyses on some mantle xenolith samples from the Northern, Southern and Austral Andean volcanic zones exhibit radiogenic Sr enrichment without dramatic changing of the Nd isotopic composition. This anomalous effect (Sr–Nd decoupling) makes these samples plot displaced to the right side of the “mantle array” trend (here called the “MORB–OIB–BSE trend”) in the 87Sr/86Sr vs. 143Nd/144Nd isotopic diagram. Such behavior reflects processes that took place in the mantle and can be related to: i) the mixture of a depleted mantle and an enriched source (enriched mantle II—EMII); ii) the mixture of a depleted mantle and a mixture of mantle-derived and slab-derived melts; and iii) a chromatographic process that occurs during the percolation of a metasomatic agent through the mantle. |
| Keywords: | Mantle Xenoliths Metasomatism Andes Sr–Nd isotopes Chromatography |
| 本文献已被 ScienceDirect 等数据库收录！ | |