Volcanic rocks from the Bolivian Altiplano: Insights into crustal structure, contamination, and magma genesis in the central Andes

Research Article| December 01, 1992 Volcanic rocks from the Bolivian Altiplano: Insights into crustal structure, contamination, and magma genesis in the central Andes Jon P. Davidson; Jon P. Davidson 1Department of Earth and Space Sciences, University of California, Los Angeles, California 90024 Search for other works by this author on: GSW Google Scholar Shanaka L. de Silva Shanaka L. de Silva 2Department of Geography and Geology, Indiana State University, Terre Haute, Indiana 47809 Search for other works by this author on: GSW Google Scholar Author and Article Information Jon P. Davidson 1Department of Earth and Space Sciences, University of California, Los Angeles, California 90024 Shanaka L. de Silva 2Department of Geography and Geology, Indiana State University, Terre Haute, Indiana 47809 Publisher: Geological Society of America First Online: 02 Jun 2017 Online ISSN: 1943-2682 Print ISSN: 0091-7613 Geological Society of America Geology (1992) 20 (12): 1127–1130. https://doi.org/10.1130/0091-7613(1992)020<1127:VRFTBA>2.3.CO;2 Article history First Online: 02 Jun 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn Email Permissions Search Site Citation Jon P. Davidson, Shanaka L. de Silva; Volcanic rocks from the Bolivian Altiplano: Insights into crustal structure, contamination, and magma genesis in the central Andes. Geology 1992;; 20 (12): 1127–1130. doi: https://doi.org/10.1130/0091-7613(1992)020<1127:VRFTBA>2.3.CO;2 Download citation file: Ris (Zotero) Refmanager EasyBib Bookends Mendeley Papers EndNote RefWorks BibTex toolbar search Search Dropdown Menu toolbar search search input Search input auto suggest filter your search All ContentBy SocietyGeology Search Advanced Search Abstract Lavas from Quaternary minor volcanic centers behind the Central Andean volcanic arc in Bolivia form a compositional continuum with rocks from the arc front, extending to more primitive compositions. The lavas show petrographic and geochemical evidence for deep crustal contamination during differentiation. Sr, Nd, and Pb isotopic data from centers within 30 km of each other encompass the entire range found in the Central Volcanic zone of the Andes. The most mafic rocks are largely typical of arc magmas elsewhere, and may represent parental magmas to the porphyritic andesites and dacites erupted from stratovolcanoes along the arc to the west. Andean arc magmas therefore undergo considerable contamination during ascent through the thick crust. The only basalts lacking petrographic evidence for contamination are picrobasalts from Chiar Kkollu that form the most primitive end member of the compositional spectrum. These rocks resemble ocean-island basalts in some respects, indicating that variations in crustal contamination across the strike of the arc may be superimposed on variations in the mantle source composition. This content is PDF only. Please click on the PDF icon to access. First Page Preview Close Modal You do not have access to this content, please speak to your institutional administrator if you feel you should have access.