Gravity characterization of the La Rioja Valley Basin, Argentina

Abstract

The La Rioja Valley is a sedimentary basin in the Pampean Ranges, a region of basement uplifts and broad valleys in the Andean foreland. The present study advances understanding of the genesis of the basin by providing subsurface data on its geometry and characteristics. Gravity and topographic data, including a newly completed gravity survey, were integrated to create a complete Bouguer anomaly map. Euler and Werner deconvolution techniques sum with traditional potential-fields methods and sparse independent data from seismic and magnetotelluric methods to test and constrain the subsurface geophysical characterization of the La Rioja Valley Basin. The residual anomaly, obtained through upward continuation, was inverted to obtain the best 3D gravity model of the La Rioja Valley Basin, which shows the first-order geometry of the basin. This reveals that the basin is asymmetric, with up to [Formula: see text] of low-density basin fill in a depocenter located in the west-central sector of the valley. Second-order features of the basin include a southeast-trending basement high, likely a fault zone that subdivides the basin, which has been revealed by a suite of analytical methods (3D model of depth to basement, a 2D inverse model, and Werner deconvolution solutions).

The evolution of the high‐elevated depocenters of the northern Sierras Pampeanas (ca. 28˚ SL), Argentine broken foreland, South‐Central Andes: the Pipanaco Basin

“…The errors involved in the depth calculations are shown as a function of the gravity effect and density variations (Appendix). Note that the largest error in the basement depth within the central part of the basin is ±800 m. Gravity studies in the Rioja basin (Gimenez et al ., ), south of the Pipanaco basin, assisted us in evaluating input parameters for the gravity model of the Pipanaco basin and in correcting the preferred densities and interpretations. Seismic data from La Rioja Basin serve to correct and correlate gravity information (Gimenez et al ., ).…”

“…In addition, we have access to geophysical subsurface data from nearby areas (e.g. Febrer et al ., ; Fisher et al ., ; Cristallini et al ., ; Mortimer et al ., ; Mcglashan et al ., ; Gimenez et al ., ) that support and complement our field and gravity observations.…”

Fast gravity inversion of basement relief

“…Among the geophysical methods directed at oil prospecting, the gravity method proved to be efficient and economic (Bott, 1960;Corbató, 1965;Tanner, 1967;El-Batroukh and Zentani, 1980;Kieniewicz and Luyendyk, 1986;Barbosa et al, 1997;Silva et al, 2006;Barbosa et al, 2007;Gimenez et al, 2009). In the past six decades, the gravity interpretation of sedimentary basins has evolved in a winding trajectory in response to the ability of the current computer speed and memory to handle an ever increasing quality and quantity of data and meet the ever increasing geologists' demand of information.…”

Quaternary deformation and stress field in the Río de la Plata Craton (Southeastern South America)

“…It is a transformation of the potential field measured on a surface, to a field that would be measured on another surface situated at a greater distance from the source (Pacino and Introcaso, 1988;Blakely, 1995). This transformation softens the effect of bodies near the surface or with a short wavelength (Gimenez et al, 2009). A Butterworth filter was also tested by applying a 250 km window and 8 order (Gimenez et al, 2011).…”

“…Specific methods were applied for the separation of gravitational effects on the complete Bouguer anomaly map. This is the result of the superposition of shallow, intermediate, and deep bodies, which are expressed as short, medium, and long wavelengths, respectively (Gimenez et al, 2009). Filtering techniques for gravimetric data were applied to remove long wavelength features attributable to Moho depth variation (Martinez and Gimenez, 2003) and to highlight the shorter wavelength features attributable to sedimentary basin geometry and structures (Gimenez et al, 2009).…”