Research Article| July 01, 2005 Potassic-ultrapotassic mafic rocks delineate two lithospheric mantle blocks beneath the southern Peruvian Altiplano G. Carlier; G. Carlier 1IRD, UR X199, 213, rue la Fayette, 75480 Paris, France, and Centre National de la Recherche Scientifique, UMR 7160 (Minéralogie-Pétrologie) and MNHN, USM 201, 61, rue Buffon, 75005 Paris, France Search for other works by this author on: GSW Google Scholar J.P. Lorand; J.P. Lorand 2Centre National de la Recherche Scientifique, UMR 7160 (Minéralogie-Pétrologie) and Muséum National d'Histoire Naturelle, USM 201, 61, rue Buffon, 75005 Paris, France Search for other works by this author on: GSW Google Scholar J.P. Liégeois; J.P. Liégeois 3Isotope Geology, Musée Royal de l'Afrique Centrale, B-3080 Tervuren, Belgium Search for other works by this author on: GSW Google Scholar M. Fornari; M. Fornari 4l'Institut de Recherche pour le Développement, UMR 6526 Géosciences Azur, Université de Nice-Sophia Antipolis, Parc Valrose, 06108 Nice cedex 02, France Search for other works by this author on: GSW Google Scholar P. Soler; P. Soler 5Laboratoire d'Océanographie Dynamique et de Climatologie, UMR 7617 CNRS/IRD/UPMC/MNHN, Mision en el Peru, La Mariscala 115, San Isidro, Lima 18, Peru Search for other works by this author on: GSW Google Scholar V. Carlotto; V. Carlotto 6INGEMMET, Avenida Canada 1470, San Borja, Lima 41, Peru Search for other works by this author on: GSW Google Scholar J. Cárdenas J. Cárdenas 7Universidad Nacional San Antonio Abad del Cusco, Avenida de la Cultura, Cusco, Peru Search for other works by this author on: GSW Google Scholar Geology (2005) 33 (7): 601–604. https://doi.org/10.1130/G21643.1 Article history received: 22 Feb 2005 rev-recd: 16 Mar 2005 accepted: 17 Mar 2005 first online: 02 Mar 2017 Cite View This Citation Add to Citation Manager Share Icon Share Facebook Twitter LinkedIn MailTo Tools Icon Tools Get Permissions Search Site Citation G. Carlier, J.P. Lorand, J.P. Liégeois, M. Fornari, P. Soler, V. Carlotto, J. Cárdenas; Potassic-ultrapotassic mafic rocks delineate two lithospheric mantle blocks beneath the southern Peruvian Altiplano. Geology 2005;; 33 (7): 601–604. doi: https://doi.org/10.1130/G21643.1 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 The Altiplano of southern Peru displays a large spectrum of Cenozoic potassic (K) and ultrapotassic (UK) mafic rocks that delineate two deep lithospheric mantle blocks that have undergone different depletion and enrichment events. Phlogopite lamproites indicate that the eastern Altiplano block is underlain by a metasomatized harzburgitic mantle of Paleoproterozoic to Archean age (depleted mantle age, TDM = 1130–2485 Ma; εNd = −5.0 to −11.4; 87Sr/86Sri = 0.7100–0.7159). Beneath the western Altiplano block, the presence of a younger (TDM = 837–1259 Ma; εNd = +0.6 to −6.3; 87Sr/86Sri = 0.7048–0.7069) metasomatized lherzolitic mantle is deduced from multiple occurrences of diopside-rich K-UK lavas (leucitites, leucite-bearing tephrites, olivine, and diopside trachybasalts). A third suite of young (<2 Ma) K-UK rocks outlines the active Cusco Vilcanota fault system separating the western and eastern Altiplano blocks; this third suite, composed of diopside-phlogopite lamproites and augite kersantites, minettes, and trachybasalts, sampled a composite mantle source that probably included an asthenospheric component (TDM = 612–864 Ma; εNd = −1.1 to −3.5; 87Sr/86Sri = 0.7051–0.7062), in addition to lithospheric components inherited from the eastern and western Altiplano blocks. The spatial distribution of the south Peruvian K-UK magmatism suggests that K-UK melts reached the surface through reuse of older translithospheric weakness zones extending at least to the depth of magma generation. These latter were reactivated by a dextral transpressional regime imposed on the two rigid lithospheric blocks by the Andean orogen. You do not have access to this content, please speak to your institutional administrator if you feel you should have access.