Special Issue dedicated to Francisco Hervé: Global tectonic processes of the ancient southwestern Gondwana margin in South America and the Antarctic Peninsula
Edited by:
- Mauricio Calderón, PhD, Universidad del Desarrollo, Chile
- Paula Castillo, PhD, Universität Münster, Deutschland
- Robert Pankhurst, PhD ScD, United Kingdom
Submission status: Extended until September 30, 2025
Special Issue: Geoethics in Chile and Latin America - Contextual reflections for responsible geoscience
Edited by:
- Luisa Pinto, Universidad de Chile
- Hernán Bobadilla, Politecnico di Milano
- Tania Villaseñor, Pontificia Universidad Católica de Chile
- Pablo Ramírez, Universidad de Chile
- Millarca Valenzuela, Universidad Católica del Norte
Submission status: Open between August 15, 2025, and March 31, 2026
Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Ciencias Geológicas, Pabellón II, Ciudad
Universitaria, Intendente Guiraldes 2160, C1428 EGA, Núñez, Buenos Aires, Argentina.
CONICET-Universidad de Buenos Aires, Instituto de Geociencias Básicas y Aplicadas de Buenos Aires (IGEBA), Pabellón II, Ciudad Universitaria, Intendente Guiraldes 2160, C1428 EGA, Núñez, Buenos Aires, Argentina. Argentina
Adriana Ramos
CONICET-Universidad de Buenos Aires, Instituto de Geociencias Básicas y Aplicadas de Buenos Aires (IGEBA), Pabellón II, Ciudad
Universitaria, Intendente Guiraldes 2160, C1428 EGA, Núñez, Buenos Aires, Argentina. Argentina
Vanesa D. Litvak
Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Ciencias Geológicas, Pabellón II, Ciudad
Universitaria, Intendente Guiraldes 2160, C1428 EGA, Núñez, Buenos Aires, Argentina.
CONICET-Universidad de Buenos Aires, Instituto de Estudios Andinos Don Pablo Groeber (IDEAN), Pabellón II, Ciudad Universitaria, Intendente Guiraldes 2160, C1428 EGA, Núñez, Buenos Aires, Argentina. Argentina
Sonia Quenardelle
Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Ciencias Geológicas, Pabellón II, Ciudad
Universitaria, Intendente Guiraldes 2160, C1428 EGA, Núñez, Buenos Aires, Argentina.
CONICET-Universidad de Buenos Aires, Instituto de Geociencias Básicas y Aplicadas de Buenos Aires (IGEBA), Pabellón II, Ciudad Universitaria, Intendente Guiraldes 2160, C1428 EGA, Núñez, Buenos Aires, Argentina. Argentina
Emma B. Maisonnave
Universidad de Buenos Aires, Facultad de Ciencias Exactas y Naturales, Departamento de Ciencias Geológicas, Pabellón II, Ciudad
Universitaria, Intendente Guiraldes 2160, C1428 EGA, Núñez, Buenos Aires, Argentina.
CONICET-Universidad de Buenos Aires, Instituto de Geociencias Básicas y Aplicadas de Buenos Aires (IGEBA), Pabellón II, Ciudad Universitaria, Intendente Guiraldes 2160, C1428 EGA, Núñez, Buenos Aires, Argentina. Argentina
Iris Díaz
Servicio Geológico Minero Argentino (SEGEMAR), Delegación San Juan, Sargento Cabral 685 (Oeste), (5400) San Juan, Argentina. Argentina
Southern Central Andes Neogene magmatism over the Pampean Flat Slab: implications on crustal and slab melts contribution to magma generation in Precordillera, Western Argentina
Stella Poma, Adriana Ramos, Vanesa D. Litvak, Sonia Quenardelle, Emma B. Maisonnave, Iris Díaz
Abstract
A Miocene to Pliocene (13 to 4.6 Ma) mostly pyroclastic sequence is exposed along the Iglesia Valley, to the east of the former main volcanic arc. This area is a transitional region between Cordillera Frontal and Precordillera, over the f lat slab segment of the Southern Central Andes, at 29º30’ S to 30º00’ S. New radiometric ages, geochemical data, petrography and field relationships are evaluated to establish differences and similarities between Miocene arcrelated sequences across the main arc and its expansion towards a back arc position, in western Precordillera. Analyzed rocks have a magmatic arc signature partially like the former main volcanic arc to the west. The Iglesia Valley rocks are LREE-enriched (La/Sm: 3.7-6.5) with respect to HREE (Sm/Yb: 2.2-6.0) and define patterns with a pronounced slope. Sm/Yb ratios generally increase with time, as pressures increase, with retention of HREE in residual mineralogy, particularly garnet at Sm/Yb>4. Volcanic activity in Cordillera Frontal and the volcanic-volcaniclastic expression in Precordillera show a continuous increase in the La/Yb ratio with decreasing age. Variations in the residual mineralphase equilibrating with magmas would be related to the progressive increase in crustal thickness due to the tectonic compressive regime resulting from shallow subduction since Middle Miocene. The data presented suggest that the arc magmatic activity during the Miocene was expanded notably to the East in relation to the location of the main arc at Valle del Cura, in Cordillera Frontal. The extensive amplitude of the volcanic arc activity is indicative of the slab gradual f lattening. Particularly, the mantle-derived magmas from Lomas del Campanario Formation (Western Precordillera) are enriched by subduction related f luids but also by crustal components. It is interpreted that the cause of the geochemical differences between the back arc position rocks and the main arc lay in the heterogeneous composition of the underlying continental crust involved in both locations. Presence of volcanic rocks with adakitic geochemical affinity probably ref lect astenospheric-derived melts that interacted through a heterogeneous and thickened crust toward the surface.