Sr, Nd, Pb and O isotope composition of late Cenozoic volcanics, northernmost SVZ (33-34°S)

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Authors:Stern, C. R.; Futa, K.; Muehlenbachs, K.; Dobbs, F. M.; Muñoz, J.; Godoy, E.; Charrier, Reynaldo
Author Affiliations:Primary:
Univ. Colo., Dep. Geol. Sci., Boulder, CO, United States
Dartmouth Coll., United States
U. S. Geol. Surv., United States
Univ. Alberta, Dep. Geol., Canada
Univ. Santiago, Dep. Minas, Chile
Serv. Nac. Geol. y Min., Chile
Univ. Chile, Dep. Geol. y Geofis., Chile
Volume Title:Andean magmatism; chemical and isotopic constraints
Volume Authors:Harmon, R. S., editor; Barreiro, Barbara A.
Source:p.96-105; American Geophysical Union, special symposium ; Andean magmatism; chemical and isotopic constraints, Baltimore, MD, June 1983, edited by R. S. Harmon and Barbara A. Barreiro. Publisher: Shiva Publ., Nantwich, United Kingdom. ISBN: 0-906812-60-7
Publication Date:1984
Note:In English. Shiva Geol. Series; illus. incl. 1 table
Summary:The volcanic centres of the northernmost segment of the SVZ are more similar to those of the CVZ between 16-28°S than to those further south in the SVZ, with respect to both the common presence of hydrous minerals, and the volumetric dominance of intermediate and silicic rocks. In the northern section of the SVZ, although the basalts and andesites have 87Sr/86Sr and 143Nd/144Nd ratios which are similar to those in the southern segment, they are more radiogenic with respect to Sr isotope composition and the rhyolites are significantly more radiogenic. In addition, the rhyolites have significantly higher delta 18O values than the associated mafic and intermediate rocks. The basalts and andesites from this zone are similar with respect to O isotope composition both to each other and to the intermediate and mafic rocks from the southern part of the SVZ. The Pb isotope compositions of basalts, andesites, dacites and rhyolites are similar throughout both the SVZ and Austral volcanic zone as far south as 52°S. The available geochemical data cannot distinguish unambiguously between two possible models of petrogenesis - incorporation of crustal components either during passage of mantle-derived mafic magmas through the lower continental crust or by their introduction by subduction processes into the mantle source region where these magmas were generated. [J.M.H.]
Subjects:Alkaline earth metals; Andesites; Assimilation; Basalts; Cenozoic; Continental crust; Crust; Fractional crystallization; Geochemistry; Igneous rocks; Isotopes; Lead; Magmas; Mantle; Metals; Neodymium; O-18/O-16; Oxygen; Quaternary; Rare earths; Rhyolites; Sr-87/Sr-86; Stable isotopes; Stratovolcanoes; Strontium; Subduction; Trace elements; Volcanic belts; Volcanic rocks; Volcanoes; Volcanology; Andes; Chile; Santiago Chile; South America; Valparaiso Chile; Aconagua Province; Evolution; Ratios
Coordinates:N330000 N340000 W0700000 W0720000
Abstract Numbers:85M/1690
Record ID:1985005783
Copyright Information:GeoRef, Copyright 2019 American Geosciences Institute. Reference includes data from Mineralogical Abstracts, United Kingdom, Twickenham, United Kingdom
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