Modelo gravimétrico en el borde noreste del macizo norpatagónico

Abstract

ABSTRACT. We present a gravimetric study on the northeast edge of the North Patagonian massif in the province of Rio Negro, to ascertain the depth distribution of the different outcrop units in the study area, as well as the geometry of the Navarrete Plutonic Complex. The negative anomalies in the Bouguer residual map reproduce the lateral density contrast between what would be the bedrock of Cambrian age and the lithologic units of the Mesozoic age. The solutions of the analytical signal along with variations in the curve of the horizontal gradient of gravity, obtained along a profile across the outcrops of the Navarrete Plutonic Complex, show contacts between the intrusive body and the bedrock with different densities. Over this profile we obtained a 2D (dimensional) gravimetric forward model adjusted with the density data of the surface rocks. Above the outcrop of the Yaminué Complex there exists a gravimetric high which does not correspond to the density in this area. This is a new evidence that proves that it is a series of intrusions and thin subhorizontal tectonic slices and that its thickness is probably thin. On the other hand the Navarrete Pluton shows the greatest development in size and depth to the east of Treneta stream.Keywords: gravimetry, Navarrete Pluton, through, Yaminué Complex. RESUMEN.Se presenta un estudio gravimétrico en el borde noreste del macizo Norpatagónico provincia de Río Negro, con el objeto de conocer la distribución en profundidad de las distintas unidades aflorantes en elárea de estudio, como así también, la geometría del Complejo Plutónico Navarrete. Las anomalías negativas en el mapa residual de Bouguer reproducen el cambio lateral de densidad entre lo que sería el basamento de edad Cámbrica y las unidades litológicas de edad Mesozoica. Las soluciones de la señal analítica junto a las variaciones en la curva del gradiente horizontal de la gravedad, obtenidas a lo largo de un perfil transversal a los afloramientos del Complejo Plutónico Navarrete, evidencian contactos entre el cuerpo intrusivo y la roca de caja de diferente densidad. Sobre este perfil se obtiene un modelo de inversión gravimétrico 2D ajustado con datos de densidad de rocas en superficie. Sobre el afloramiento del Complejo Yaminué existe un máximo gravimétrico que no se corresponde con su densidad en superficie. Esto es una nueva evidencia de que el mismo es una serie de intrusiones y escamas tectónicas delgadas subhorizontales y que su espesor es probablemente de poca magnitud. Por otro lado el Plutón Navarrete muestra mayor desarrollo en su tamaño y profundidad hacia el este del arroyo Treneta.Palabras-clave: gravimetría, plutón Navarrete, profundidades, Complejo Yaminué.

Jurassic cooling ages in Paleozoic to early Mesozoic granitoids of northeastern Patagonia: 40Ar/39Ar, 40K–40Ar mica and U–Pb zircon evidence

“…Gonzalito/Tembrao blocks. The blocks themselves are separated by steep NE-SW and NW-SE shear zones and/ or faults (Von Gosen, 2003) or lineaments that bound gravimetric and aeromagnetic anomalies (Croce et al, 2009;Lince Klinger et al, 2010Chernicoff et al, 2013;figure 1b). These anomalies coincide with the exposures of the Triassic to Jurassic (?)…”

“…Other evidence of Jurassic intraplate deformation are referred in the wake of uplift of the Huincul High, NW of Patagonia(Naipauer et al, 2012) and the discrete events of tectonic inversion of the West-Gondwana break up related depocenters in the Deseado Massif(Navarrete et al, 2016). 2013;Rapalini et al, 2013). The black double line represents the contact lineament between the Yaminué block and the Nahuel Niyeu block according to the gravimetrical model ofLince et al (2010Lince et al ( , 2014,Rapalini et al (2010) and magnetometrical data ofChernicoff et al (2013).…”

Emplacement and temporal constraints of the Gondwanan intrusive complexes of northern Patagonia: La Esperanza plutono-volcanic case

“…Another lines of evidence in the plethora of hypotheses, would support no collision (Gregori et al, 2013(Gregori et al, , 2008 or intraplate deformation and magmatism (Gregori et al, 2016) and regional continuity of the intraplate Choiyoi magmatic province into Patagonia (Rapela and Llambías, 1985). These proposals have been revisited in the recent years with evidence in favor of one or other model (Chernicoff et al, 2013;González et al, 2012;Lince Klinger et al, 2014;Pankhurst et al, 2014Pankhurst et al, , 2006Rapalini, 1998;Rapalini et al, 2010).…”

Gravimetric determination of the continental–oceanic boundary of the Argentine continental margin (from 36°S to 50°S)

“…Filtering consisted of calculating the upward continuation that has operated as a low pass filter (Pacino & Introcaso 1987;Pacino 1989;Pawlowski 1995;Guo et al 2013) of Bouguer anomalies with geological correction in the Fourier domain using Dirichlet's equation according to Dean (1958). Thus, Bouguer anomalies with geological correction represent the gravitational effect of the lower crust (Ruiz & Introcaso 1999;Lince Klinger et al 2010).…”