Cambios Periódicos De Gravedad Vinculados Con Tectónica Activa En La Precordillera Oriental, San Juan, Argentina

New data on neotectonic contractional structures in Precordillera, south of Río de La Flecha: Structural setting from gravity and magnetic data. San Juan, Argentina

“…These anomalies consist of long wavelength and come from deeper sources (basement sources). The San Juan City basement block has high vertical crustal mobility, the boundaries of which agree with three 4D gravimetric gradients of about À0.005 mGal/yr (Ruiz et al, 2011b). The contour lines of gravity time variations in are show in Fig.…”

“…Terrain corrected Bouguer anomalies were calculated from 5000 gravity stations collected by IGSV (Ruiz and Introcaso, 2004;Ruiz et al, 2011b). The total field magnetic anomaly mosaic was prepared by merging data from two aeromagnetic surveys (SEGEMAR, 1999(SEGEMAR, , 2001.…”

“…In addition, Ruiz et al (2011b) have shown gravity time variations (4D gravity) produced by ongoing tectonic activity from a geodetic network extended over an area of 3500 km 2 centered on San Juan City. These gravity changes obtained during the years 2000e2009 from periodic gravity measurements support the current uplift of the Eastern Precordillera.…”

“…2b. (4) The analytic signal map reveals regional lineaments running transversal to the orogenic front: (a) Salinas Grandes Megafracture, (b) Barboza-Médanos Grandes lineament (Ruiz et al, 2011b), (c) La Flecha fault, (d) Guanacache fault, (e) Acequión Fault and (f) Barreal-Las Peñas Belt. These transversal lineaments show displacements in its trend through the PrecordilleraePie de Palo contact, inferred from the anomaly patterns.…”

“…These magnetic highs delineate: (a) the Cerro Blanco pluton, (b) the Sierra Pie de Palo ophiolitic complex (Vujovich, 2003), (c) Cerro Valdivia and Cerro Salinas, (d) Carboniferous and Neogene deposits and (e) possible minor intrusive subsurficial bodies. Ruiz et al (2011b) using 4D gravity data combined with gravity and magnetic anomalies analysis have shown the existence of a conspicuous lineament of maxima that connects the western margin of Sierra Pie de Palo with Barboza and Valdivia hills and converging to the Eastern Precordillera at the latitude of La Flecha River. This lineament is the geophysical evidence of the Tulum fault system, with Quaternary tectonic activity which represents a basement structural high, buried bellow the Tulum basin.…”