Andean Magmatism, 1984
Chemical and Isotopic Constraints

Destructive plate margin magmagenesis is one of the most intensely studied and widely debated topics in the earth sciences at present. Calc-alkaline volcanic and plutonic rocks in orogenic settings exhibit such a diversity of composition and character that the subducted oceanic lithosphere, the overlying 'enriched' lithospheric mantle and the lower continental crust all have been advocated recently as the primary source region for island-arc and continental-margin basaltic to andesitic magmas. The role of the upper continental crust is also a matter of continuing controversy. It is clear that crustal contamination is a common, but not universal, feature of destructive plate margin magmatism. Whether this contamination is introduced at source by subduction-related processes or occurs during magma transit by bulk anatexis and magma mixing, selective contamination or coupled fractional crystallization-assimilation mechanisms is central to most current discussions of andesite petrogenesis. This book presents a series of papers which directly address these and other important geological and geochemical problems within the context of the Mesozoic-Cenozoic calc-alkaline magmatism characteristic of the Andean Cordillera of western South America. Although it is aimed primarily at postgraduate students and researchers familiar with the Andes, it is also a useful general reference for workers in other fields who wish to gain an insight into current thoughts, ideas and speculations on 'andesitic' magmatism at destructive plate margins.

Section 1: Volcanic Andes.- The tectonic setting of active Andean volcanism.- Oxygen isotope ratios in Late Cenozoic Andean volcanic.- Lead isotopes and Andean magmagenesis.- Isotope and trace element data for orogenic andesites from the Austral Andes.- Petrology and chemistry of volcanic rocks of the Southern Andes.- Geochemical variations in volcanic rocks from central-south Chile (33–42°S).- Sr, Nd, Pb and O isotope composition of Late Cenozoic volcanics, northernmost SVZ (33–34°S).- The Cerro Purico shield complex, north Chile.- Quantitative models for crustal contamination in the central and northern Andes.- Correlated Sr isotope and geochemical variations in basalts and basaltic andesites from Guatemala.- Section 2: Plutonic Andes.- Phanerozoic plutonism in the Peruvian Andes.- The Coastal Batholith of Peru.- Lead isotope systematics in batholithic rocks of the Western and Coastal Cordilleras, Peru.- Geochemical characteristics of the Late Mesozoic Andean volcanic.- The magmatic evolution of the Cordillera Oriental, southeastern Peru.- Geochemical characteristics of magmatism in the Southern Andes (45–46°S).- References.