Chemical and isotopic constraints on the origin of low-silica latite and andesite from the Andes of central Peru
Document Type
Article
Publication Date
1-1-1975
Abstract
Low-silica latite highly enriched in large-ion-lithophile elements and moderately potassic low-Si andesite were erupted in central Peru during late Cenozoic time. FeO*/MgO ratios of 0.93 to 1.25 at 53 wt percent SiO2 indicate a definitely calc-alkalic character. The combination of low FeO*/MgO ratios, low SiO2, and high Cr, Co, and Ni with large-ion-lithophile and light rare-earth elements makes it very unlikely that the parent magmas were produced by high-pressure partial melting of subducted ocean-floor basalt (eclogite). The data are more compatible with small degrees of partial melting of ultramafic material or mixtures of basalt and ultra-mafic mantle. The initial melts probably contained 52 to 53 percent SiO2 and had a content of large-ion-lithophile elements nearly as high as that of the rocks. Sr87/Sr86 ratios of from 0.7042 to 0.7051 and low to very low Rb/Sr ratios indicate an isotopically variable source region that, at least in part, had earlier been depleted in Rb relative to Sr. © 1975 Geological Society of America.
Publication Title
Geology
Recommended Citation
Noble, D.,
Bowman, H.,
Hebert, A.,
Silberman, M.,
Heropoulos, C.,
Fabbi, B.,
&
Hedge, C.
(1975).
Chemical and isotopic constraints on the origin of low-silica latite and andesite from the Andes of central Peru.
Geology,
3(9), 501-504.
http://doi.org/10.1130/0091-7613(1975)3<501:CAICOT>2.0.CO;2
Retrieved from: https://digitalcommons.mtu.edu/michigantech-p/12287
