A crustal model based mainly on gravity data in the area between the Bermejo Basin and the Sierras de Valle Fértil, Argentina

Giménez, Mario; Martinez, María Alejandra; Introcaso, Antonio

doi:10.1016/s0895-9811(00)00012-2

Cited by 41 publications

(37 citation statements)

References 17 publications

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“…Tilting and uplifting of the studied crustal section during emplacement in the upper crust might be primarily related to the collision between a Laurentia-derived terrane and the proto-Pacific margin of Gondwana (Thomas and Astini, 1996;Ramos et al, 1996). The strongest evidence for the existence of two distinct continental landmasses is the existence of a paleo-suture called the Valle Fértil lineament along the western border of the Sierras Valle Fértil and La Huerta (Giménez et al, 2000;and Fig. 1).…”

Section: Local Geological Features From the Sierras Valle Fértil-la Hmentioning

confidence: 99%

Geology and petrology of a deep crustal zone from the Famatinian paleo-arc, Sierras de Valle Fértil and La Huerta, San Juan, Argentina

Otamendi

Vujovich

Rosa

et al. 2009

Journal of South American Earth Sciences

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Section: Local Geological Features From the Sierras Valle Fértil-la Hmentioning

confidence: 99%

Geology and petrology of a deep crustal zone from the Famatinian paleo-arc, Sierras de Valle Fértil and La Huerta, San Juan, Argentina

Otamendi

Vujovich

Rosa

et al. 2009

Journal of South American Earth Sciences

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“…(2) The relative positive gravity response of the Precordillera within the general negative trend marked by the Andean root is clearly depicted (Introcaso et al 1992a;Gimenez et al 2000Gimenez et al , 2009Alvarez et al 2012). …”

Section: Resultsmentioning

confidence: 99%

“…7). This anomaly has been linked to potential mafic bodies buried at the contact zone between the Cuyania and Pampia terrains (Introcaso & Pacino 1987;Ramos 1994;Miranda & Introcaso 1999;Gimenez et al 2000;Martinez et al 2007). This was resolved by modelling the crust assigned to the Pampia terrain with a higher density (r ¼ 2720 kg m 23 ).…”

Section: Profilementioning

confidence: 99%

Geophysical characterization of the upper crust in the transitional zone between the Pampean flat slab and the normal subduction segment to the south (32–34°S): Andes of the Frontal Cordillera to the Sierras Pampeanas

Sánchez

Klinger

Martinez

et al. 2014

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The Nazca Plate subducting beneath the South American Plate has strongly influenced Cenozoic mountain growth in western Argentina and Chile sectors (32–34°S; 70–66°W). At these latitudes, the Pampean flat slab has induced the development of prominent mountain systems such as the Frontal Cordillera, the Precordillera, and the associated Sierras Pampeanas in the eastwards foreland region. Through a gravity study from the Frontal Cordillera to the Sierras Pampeanas region between 32 and 34°S, we delimit a series of geological structures that are accommodating shortening in the upper crust and others of regional and subsurface development, without any clearly defined mechanics of deformation. Additionally, through an isostatic residual anomaly map based on the Airy-Heiskanen local compensation model, we obtain a decompensative gravity anomaly map that highlights anomalous gravity sources emplaced in the upper crust, related to known geological structures. In particular, by applying the Tilt method which enhances the gravity anomalies, the NW-trending Tunuyan Lineament is depicted south of 33.4°S following previous proposals. Using the decompensative gravity anomaly, two profiles were modelled through the northern sector of the study area using deep seismic refraction lines, borehole data and geological information as constraints. These density models of the upper crust of this structurally complex area accurately represent basin geometries and basement topography and constitute a framework for future geological analysis.

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“…La falla principal que eleva el bloque serrano coincide, a escala regional, con la megafractura de Valle Fértil (Baldis et al, 1990), la cual se extiende a lo largo del borde occidental de las sierras (Snyder et al, 1990;Zapata y Allmendinger, 1996;Zapata, 1998;Ortiz et al, 2015). Datos de gravimetría indican la existencia de una discontinuidad en la cuenca del río Bermejo que flanquea las sierras por el oeste (Giménez et al, 2000;Lince et al, 2008), la cual correspondería con la megafractura de Valle Fértil sugerida como el límite entre el terreno aloctóno derivado de Laurentia y el margen autóctono de Gondwana (Thomas y Astini, 1996;Ramos et al, 1996). Los estudios regionales de corteza que incluyen la zona bajo estudio, proponen distintas propiedades geofísicas para el sector occidental (terreno Cuyania), de aquellas observadas hacia el este, en el terreno Pampia de naturaleza más granítica, con ambos sectores en contacto a través de la citada megafractura .…”

Section: Arco Geológicounclassified

Modelo petrofísico del borde oriental de las sierras de Valle Fértil- La Huerta, Argentina a partir de datos sísmicos y petrológicos

et al. 2017

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This paper is a contribution to the knowledge of the crustal structure of the eastern flank of the Valle Fértil - La Huerta ranges (Western Sierras Pampeanas, San Juan, Argentina) at 31°S, in the Andean foreland region, where the Nazca plate is subducting horizontally at about 100 km depth. A 1D velocity model was constrained, combining petrographic and seismological observations from analysis of 19 igneous and metaigneous plutonic rocks belonging to the Famatinian (Ordovician) magmatic arc, which make up most of the crystalline basement of these ranges. Granitoid lithologies predominate in the northern region whereas mafic lithologies are more common to the south. The seismological analysis consisted of modeling teleseismic receiver functions near three seismological stations: LUNA, MAJA and CHUC, in places where those rocks are dominant. Thus, P and S seismic-wave velocities (Vp and Vs) and Poisson´s coefficient (ν), among other elastic parameters, were obtained. The seismic velocity model indicates an overthickened crust with an average thickness between 55 and 60 km, which matches with global average values (~41km); this agrees well with the hypothesis of partial eclogitization in the lower crust. The presence of two seismic velocity discontinuities at mid-crustal levels (12 and 28 km depths), likely associated to décollements, might be related to the accretion of the Cuyania terrane to the Pampia terrane. We obtained low P seismic-wave velocities (Vp ~5.8 km/s), Vp/Vs ratio (~1.70) in upper crust levels consistent with granitoid lithologies, as well as high P seismic-wave velocities (Vp ~6.76 km/s), Vp/Vs ratio (~1.78) in lower crust levels; these figures match with mafic lithologies of a more dense (~3.00 g/cm3), lower crust with respect to other back-arc Andean regions. Also, these values are consistent with the existence of mafic rocks composed of olivine, ortho- and clinopyroxene, which constitute the root of the Famatinian magmatic arc. These results indicate high-grade metamorphic conditions and depths corresponding to geophysical properties of middle to lower crust and correlate with the hypothesis of a dehydrated, cool and magnesium-enriched mantle located in the region between the subducted Nazca slab and the bottom of the Cuyania terrain crust.

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A crustal model based mainly on gravity data in the area between the Bermejo Basin and the Sierras de Valle Fértil, Argentina

Cited by 41 publications

References 17 publications

Geology and petrology of a deep crustal zone from the Famatinian paleo-arc, Sierras de Valle Fértil and La Huerta, San Juan, Argentina

Geology and petrology of a deep crustal zone from the Famatinian paleo-arc, Sierras de Valle Fértil and La Huerta, San Juan, Argentina

Geophysical characterization of the upper crust in the transitional zone between the Pampean flat slab and the normal subduction segment to the south (32–34°S): Andes of the Frontal Cordillera to the Sierras Pampeanas

Modelo petrofísico del borde oriental de las sierras de Valle Fértil- La Huerta, Argentina a partir de datos sísmicos y petrológicos

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