Anomalías gravimétricas y magnéticas corticales del sur de la provincia volcánica de la Payenia, asociadas al tearing de la placa de Nazca y anomalías mantélicas

RUIZ, FRANCISCO; SAGRIPANTI, LUCÍA; SOLER, SANTIAGO; COLAVITTO, BRUNO; FOLGUERA, ANDRÉS; GARCÍA, HÉCTOR PEDRO ANTONIO; ASTORT, ANA

San Miguel de Tucumán

Congreso; XX Congreso Geológico Argentino; 2017

Asociación Geológica Argentina

Cortical gravimetric and magnetic anomalies in the south of the volcanic province of la Payenia, associated to the tearing of the Nazca plate and manteclic anomalies. The Auca Mahuida volcanic shield is located on the south- ernmost part of the Payenia Volcanic Province on the retroarc of the Southern Central Andes. After a -15 My pe- riod of shallow subduction in the area (Kay 2006, Ramos y Folguera 2009), a sudden steepening of the Nazca plate during the last 4 Ma triggered a strong tearing located below the Auca Mahuida Plateau, evidenced by seismic to- mographies (Pesicek et al. 2012). Evenmore, resistivity studies from Burd et al. (2015) described a complex plume head impacting at the southern Payenia plateau, feeding individual volcanic centers. The present work provides new-high resolution gravity and aerial-magnetic data that constitute undocumented information for the interpreta - tion of the structure of the continental crust, subducted slab and upper mantle below the Auca Mahuida Plateau. A correlation between shallower resistivity isosurfaces (33-52 km depth) associated with the plume and the measured magnetic data, depicts a -150 km in diameter circular anomaly. Using the EIGEN-6c4 model, Geoid data have been filtered in order to isolate deeper mass influences. This allows identifying a good correlation between the anoma- lous masses in the upper crust, a positive undulation due to anomalous masses in the upper mantle and possibly the tearing of the ocean slab. This work provides new data on the spatial relation between an asthenospheric anomaly, the tearing produced on the Nazca plate and a laccolith intruding the upper crust.