Computer Science
Scientific paper
Jan 1982
adsabs.harvard.edu/cgi-bin/nph-data_query?bibcode=1982e%26psl..57...47j&link_type=abstract
Earth and Planetary Science Letters, Volume 57, Issue 1, p. 47-62.
Computer Science
54
Scientific paper
Systematic variations in O, Sr, Nd, and Pb isotopic ratios and in Sr, Nd, Pb, and Rb trace element abundances in central Andean andesitic lavas are analyzed in terms of combined crustal assimilation and fractional crystallization. The results of integrated isotopic model calculations show that observed local isotopic and trace element variations within the Arequipa and Barroso volcanic groups of southern Peru are best fit by a simple model involving shallow or intermediate depth crustal assimilation of Charcani gneiss (or an equivalent rock) accompanied by dominantly plagioclase fractional crystallization. A consequence of this result is that the Rb-Sr pseudoisochrons reported for the Arequipa and Barroso volcanics are wholly artifacts of the combined processes of assimilation and plagioclase fractionation, as are all of the Pb isotopic variations measured in the same lavas, already interpreted by Tilton and Barreiro [14] to be the result of crustal contamination. Isotopic and trace element compositions of the primary magmas for the Arequipa and Barroso volcanic series are obtained by correcting for assimilation and fractional crystallization. The starting magmas are characterized over the entire range of permissible primary compositions by high 87Sr/86Sr ratios, low 143Nd/144Nd ratios, and high Sr concentrations relative to ``normal'' island arc andesites. These results appear to require prior contamination of the magmas, but not involving plagioclase fractionation. The uncertainty in Pb and O isotope ratios computed for possible primary magmatic compositions is sufficiently large, however, that it is not possible to preclude a subcrustal origin for at least some regional variation in Sr and Nd isotopic ratios.
No associations
LandOfFree
A combined O, Sr, Nd, and Pb isotopic and trace element study of crustal contamination in central Andean lavas, I. Local geochemical variations does not yet have a rating. At this time, there are no reviews or comments for this scientific paper.
If you have personal experience with A combined O, Sr, Nd, and Pb isotopic and trace element study of crustal contamination in central Andean lavas, I. Local geochemical variations, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and A combined O, Sr, Nd, and Pb isotopic and trace element study of crustal contamination in central Andean lavas, I. Local geochemical variations will most certainly appreciate the feedback.
Profile ID: LFWR-SCP-O-1456366