Anomalías Gravimétricas y Magnéticas Corticales del Sur de la Provincia Volcánica de La Payenia, asociadas al tearing de la Placa de Nazca y Anomalías Magnéticas

SAGRIPANTI, LUCÍA; RUIZ, FRANCISCO; CCOLAVITTO, BRUNO; SOLER, SANTIAGO; ASTORT, ANA; GARCÍA, HECTOR

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 mantelic anomalies. The Auca Mahuida volcanic shield is located on the southernmost part of the Payenia Volcanic Province on the retroarc of the Southern Central Andes. After a ~15 My period 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 string tearing located below the Auca Mahuida Plateau, evidenced by seismic tomographies (Pesicek et al. 2012). Evenmore, resistivity studies Burd et al. (2015) described a complex plume head impacting at the southern Payenia playeau, feeding individual volcanic centers. Yhe present work provides new high resulution gravity and aerial-magnetic data that constitute undocumented information for the interpretation 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 masured magnetic data, depicts a ~150 km in diameter circular anomaly. Using EIGEN-6c4 model, Geod data has been filtered in order to isolate deeper mass influences. THis allows identifying a good correlation between the anomalous masses in the upper crust, a positive undulation due to anomalous masses in the upper mantle and possibly the tearing if the ocean slab. This work provides new data on the spatial resolution between an asthenospheric anomaly, the tearing produced on the Nazca plate and a laccolith intruding the upper crust.