Mesoproterozoic depleted spinel peridotites metasomatized by high-K hydrous melt in the Patagonian back-arc

• Autores: dos Santos, Aline Alves; Jalowitzki, Tiago; Gervasoni, Fernanda; Mazzucchelli, Maurizio; Giovanardi, Tommaso; Schilling, Manuel Enrique; Varas Reus, Maria Isabel; Orihashi, Yuji; Rodrigues, Rodrigo Freitas; Carlson, Richard Walter; Rubiano Lorenzoni, Georgina Marianela; Hirata, Daiji; Bertotto, Gustavo Walter
• Año de publicación: 2024
• Idioma: inglés
• Tipo de recurso: artículo
• Materia: SPINEL PERIDOTITES; PARTIAL MELTING; MESOPROTEROZOIC; METASOMATISM
• Institución: Consejo Nacional de Investigaciones Científicas y Técnicas

Here we report the first investigation of spinel-bearing mantle xenoliths from Los Gemelos volcano, Canquel Plateau, Patagonia. They are highly-depleted Mesoproterozoic (Re–Os model ages of 1.3–0.9 Ga) harzburgites and clinopyroxene-poor lherzolites characterized by typical indicators of partial melt extraction, such as low whole-rock Al2O3 and CaO contents (<1.5 wt%), high Mg# of silicate phases (90–95), and Cr-rich spinel (Cr# 0.20–0.42). Depletion of incompatible highly siderophile elements (Re, Ru, Pd) relative to the primitive upper mantle supports high degrees of melt extraction. The occurrence of phlogopite and K-rich alkaline glass veins with high- and low-SiO2 compositions is clear evidence of modal metasomatism. The light rare earth element (LREE) enrichment in clinopyroxene, as well as the whole-rock U-shaped REE pattern, confirms cryptic metasomatism. This melt-rock interaction is corroborated by major (i.e., Mg# vs. basaltic elements) and trace (i.e., La/YbN vs. Sr/Y and Ti/Eu; and Sr vs. Ti/Eu) element contents of pyroxenes. The calculated compositions of melts in equilibrium with clinopyroxene coexisting with phlogopite suggest interaction with slab-derived materials. This metasomatism has been generated by a chromatographic fractionation-reaction process, from deep to shallow mantle domains. The percolation of a high-K hydrous magma probably is associated with the upwelling of asthenospheric material through a slab-window, which caused partial melting of oceanic crust and overlying sediments during the Paleocene. The varying intensities of metasomatic imprints recorded by mantle xenoliths from Los Gemelos provide valuable insights into the interaction of slab-derived materials near the lithosphere-asthenosphere boundary, at a distance of ~600 km from the Andean volcanic arc.
Fil: dos Santos, Aline Alves. Universidade do Brasília; Brasil
Fil: Jalowitzki, Tiago. Universidade do Brasília; Brasil
Fil: Gervasoni, Fernanda. Universidade Federal de Pelotas; Brasil
Fil: Mazzucchelli, Maurizio. Università di Modena e Reggio Emilia; Italia
Fil: Giovanardi, Tommaso. Università di Modena e Reggio Emilia; Italia
Fil: Schilling, Manuel Enrique. Universidad Austral de Chile; Chile
Fil: Varas Reus, Maria Isabel. Eberhard Karls Universität Tübingen.; Alemania
Fil: Orihashi, Yuji. Hirosaki University; Japón
Fil: Rodrigues, Rodrigo Freitas. Australian National University; Australia
Fil: Carlson, Richard Walter. Carnegie Institution Of Washington; Estados Unidos
Fil: Rubiano Lorenzoni, Georgina Marianela. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; Argentina
Fil: Hirata, Daiji. Kanagawa Prefectural Museum Of Natural History; Japón
Fil: Bertotto, Gustavo Walter. Consejo Nacional de Investigaciones Científicas y Técnicas. Instituto de Ciencias de la Tierra y Ambientales de La Pampa. Universidad Nacional de La Pampa. Facultad de Ciencias Exactas y Naturales. Instituto de Ciencias de la Tierra y Ambientales de La Pampa; Argentina