Crustal attenuation in the Southern Andean retroarc (38°–39°30′ S) determined from tectonic and gravimetric studies: The Lonco-Luán asthenospheric anomaly

The Loncopué Trough: A Cenozoic basin produced by extension in the southern Central Andes

“…This scenario has been interpreted as derived from asthenosphere injection in a broadened asthenospheric wedge more than 400 km away from the trench in the retroarc area, triggering extensional deformation at the upper crust ( Fig. 2B) (Folguera et al, 2007. A 2D preliminary electrical resistivity model at 36.5 • S (Burd et al, 2008) shows an "uprising highly conductive plume" with geometry compatible with the asthenospheric anomaly modeled from gravity data (Folguera et al, 2007).…”

“…2B) (Folguera et al, 2007. A 2D preliminary electrical resistivity model at 36.5 • S (Burd et al, 2008) shows an "uprising highly conductive plume" with geometry compatible with the asthenospheric anomaly modeled from gravity data (Folguera et al, 2007). The inferred extensional deformation in this segment would have expanded to the east, defining a Quaternary deformational front (Figs.…”

Copahue Volcano and Its Regional Magmatic Setting

“…There is minor evidence for post-Miocene compression south of 34°S, although north of 34°S high-angle reverse and Quaternary thrust faults in the Argentine Precordillera testify to a compressional regime existing since the Mid-Miocene (Jordan et al 1983;Garcia Morabito et al 2011;Folguera et al 2007Folguera et al , 2012Orts et al 2012). Since this time, the SSVZ region has only undergone regional extension, as the Quechua compressional phase of the Andean Orogeny ended in the late Miocene (Charrier and Vicente 1972).…”

International Lateinamerika-Kolloquium 2009

“…A southward younging of the deformation can be recognized as well. Hence, this NW-trending structural high has been reshaped during the Late Miocene after a first phase of compressional deformation between the Late Cretaceous and the Eocene constrained by fission track ages along the CPHB (Thomson et al, 2008) and the Lonquimay Massif (Gräfe et al, 2002), and related to an eastward expansion of Late Cretaceous to Eocene arc related products, which leaded Ramos and Folguera (2007) to propose a shallowing of the subducted plate for the segment located inmediatly north of the study area for that period. The main goal of our work was to obtain the stacking of the P-SV reflected converted waves.…”

“…During the last years considerable amount of information related to the youngest extensional stage (Pliocene to Quaternary) at the Loncopué trough has been obtained (García Morabito and Folguera, 2005;Folguera et al 2009), mainly related to morphological indicators such as triangular facets spatially coincident with the identified Tertiary halfgrabens. The last episode of extension in the area seems to be active based on receiver function analyses at 39ºS and gravimetric studies that show an attenuated Moho up to 30 km beneath the Loncopué trough and the Agrio fold and thrust belt (Yuan et al, 2006;Folguera et al, 2007). Bouguer anomalies show, at a broad scale, that a west dipping high angle fault juxtaposes the Agrio fold and thrust belt with the eastern Loncopué trough.…”