Mantle diversity beneath the Colombian Andes, Northern Volcanic Zone: Constraints from Sr and Nd isotopes

Rodriguez-Vargas A., Koester E., Mallmann G., Conceicao R.V., Kawashita K. and Weber M.B.I. (2005) Mantle diversity beneath the Colombian Andes, Northern Volcanic Zone: Constraints from Sr and Nd isotopes. Lithos, 82 3-4 SPEC. ISS.: 471-484. doi:10.1016/j.lithos.2004.09.027


Author Rodriguez-Vargas A.
Koester E.
Mallmann G.
Conceicao R.V.
Kawashita K.
Weber M.B.I.
Title Mantle diversity beneath the Colombian Andes, Northern Volcanic Zone: Constraints from Sr and Nd isotopes
Journal name Lithos   Check publisher's open access policy
ISSN 0024-4937
Publication date 2005
Sub-type Article (original research)
DOI 10.1016/j.lithos.2004.09.027
Volume 82
Issue 3-4 SPEC. ISS.
Start page 471
End page 484
Total pages 14
Language eng
Subject 1906 Geochemistry and Petrology
Abstract In order to provide mantle and crustal constraints during the evolution of the Colombian Andes, Sr and Nd isotopic studies were performed in xenoliths from the Mercaderes region, Northern Volcanic Zone, Colombia. Xenoliths are found in the Granatifera Tuff, a deposit of Cenozoic age, in which mantle- and crustal-derived xenoliths are present in bombs and fragments of andesites and lamprophyres compositions. Garnet-bearing xenoliths are the most abundant mantle-derived rocks, but websterites (garnet-free xenoliths) and spinel-bearing peridotites are also present in minor amounts. Amphibolites, pyroxenites, granulites, and gneisses represent the lower crustal xenolith assemblage. Isotopic signatures for the mantle xenoliths, together with field, petrographic, mineral, and whole-rock chemistry and pressure-temperature estimates, suggest three main sources for these mantle xenoliths: garnet-free websterite xenoliths derived from a source region with low P and T (16 kbar, 1065 °C) and MORB isotopic signature, 87Sr/ 86Sr ratio of 0.7030, and 143Nd/ 144Nd ratio of 0.5129. Garnet-bearing peridotite and websterite xenoliths derived from two different sources in the mantle: i) a source with intermediate P and T (29-35 kbar, 1250-1295 °C) conditions, similar to that of sub-oceanic geotherm, with an OIB isotopic signature ( 87Sr/ 86Sr ratio of 0.7043 and 143Nd/ 144Nd ratio of 0.5129); and ii) another source with P and T conditions similar to those of a sub-continental geotherm (>38 kbar, 1140-1175 °C) and OIB isotopic characteristics ( 87Sr/ 86Sr ratio=0.7041 and 143Nd/ 144Nd ratio=0.5135).
Keyword Colombian Andes
Continental accretion
Crustal xenoliths
Mantle diversity
Mantle xenoliths
Sr and Nd isotopes
Subduction zone
Q-Index Code C1
Q-Index Status Provisional Code
Institutional Status Unknown

Document type: Journal Article
Sub-type: Article (original research)
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