Fragmentation of a foreland basin in response to out-of-sequence basement uplifts and structural reactivation: El Cajon-Campo del Arenal basin, NW Argentina

Abstract

The style and mechanisms by which a foreland region is incorporated into an orogen depends on the tectonic style, effectiveness of uplift, and dynamic subsidence. Classical foreland-basin models refl ect a self-similar propagation of deformation into the foreland in a thin-skinned thrust-belt setting governed by wedge mechanics. Thick-skinned foreland regions, which are characterized by high-angle reverse-fault-bounded basement uplifts and intervening basins, however, do not fi t this idealized model. Unlike thinskinned tectonic provinces, deformation and uplift in these regions may be highly variable in time and space. Furthermore, deformation patterns may be complicated by the presence of preexisting structures, particularly those which lie at orientations that enable them to be reactivated and utilized to accommodated deformation under compression.The Neogene El Cajón-Campo del Arenal basin is one of a series of basins located along the eastern margin of the Puna Plateau within the Sierras Pampeanas, a region that is composed of a thick-skinned foreland fragmented by reverse-fault-bounded basement uplifts that regionally characterize an eastward-younging trend. This region is superimposed onto the Cretaceous Salta Rift province, which provides a series of preexisting structures that may potentially be reactivated. The basin is located along the eastern margin of the Puna Plateau, an integral component of the Andean orogen, which includes several fi lled, uplifted, and internally drained Cenozoic intraplateau basins. Structural and sedimentological similarities exist between basins along the margin of the Puna and those within it. Understanding the evolution of foreland basins, such as the El Cajón-Campo del Arenal basin, provides possible mechanisms for the development and incorporation of marginal basins into orogenic belts, and in the case of the Andean orogen, the potential for these basins to be incorporated into the plateau.Our analysis, which integrates seismic, sedimentary, and thermochronological data, characterizes the evolution of this basin and surrounding ranges. The appearance in the sedimentary section of a distinct grain-age population derived from the basement erosion surface constrains the uplift and erosion of an out-of-sequence intrabasin high to ca. 6 Ma. The basin fi ll, therefore, records an evolution from an undeformed foreland to one that is compartmentalized by basement uplifts and that is incorporated into the greater orogenic structure. The data reveal the importance of the reactivation of preexisting structures along the basin margin in creating east-dipping structures in a generally west-dipping domain. These opposing faults on the basin margin consequently caused the out-of-sequence uplift of the intrabasin range, the Sierra de Quilmes. The Sierra de Quilmes fragments the foreland and, because its position is locked by loads to the west and east, creates increased deformation within the basin, basin fi ll, uplift, and incorporation into the orogen. Unlike basins within the plateau...

Basin fragmentation controlled by tectonic inversion and basement uplift in Sierras Pampeanas and Santa Bárbara System, northwest Argentina

“…The Sierra de Quilmes uplift was also dated by apatite fission track data and indicates a similar age of exhumation, approximately of 6 Ma. (Mortimer et al 2007). Neotectonic activity was documented in both margins of the Sierra de Aconquija (Drozdzewski & Mon 1999;Cristallini et al 2004).…”

“…6b). In this sector, no Cretaceous syn-rift or post-rift deposits are present (Strecker et al 1989;Mortimer et al 2007;Bossi & Muruaga 2009). Few and small outcrops of the Salta Group deposits are found in the foothills of the eastern slope of the Sierra de Aconquija (Fig.…”

“…6c). The Sierra de Quilmes is characterized by the absence of outcropping faults controlling both slopes of the range (Mortimer et al 2007). In the eastern part of the Sierra de Quilmes, the Santa María Basin presents foreland layers directly on top of the basement with no Salta Group deposits in the stratigraphic record (Strecker et al 1989;Bossi et al 2001;Sobel & Strecker 2003).…”

Orogenic wedge advance in the northern Andes: Evidence from the Oligocene-Miocene sedimentary record of the Medina Basin, Eastern Cordillera, Colombia

“…However, a nonsystematic pattern of lateral orogenic growth or the absence of typical wedge geometries may occur in those settings, where favorably oriented basement anisotropies in front of an orogenic wedge may absorb shortening. This is apparently the case in the Santa Barbara system and the northern Sierras Pampeanas of NW Argentina, where deformation tends to be accommodated along basement inhomogeneities inherited from previous tectonic events (e.g., Allmendinger et al, 1983;Ramos et al, 2002;Hilley et al, 2005;Mortimer et al, 2007).…”

Endorheic Basins

“…In the Andean foreland of NW Argentina, alluvial fan, alluvial plain, and lacustrine deposits of Neogene age are described as having formed in a basin of internal drainage (Mortimer et al, 2007). From the late Eocene to the late Miocene, the Ebro Foreland basin flanking the southern Pyrenees was an area of alluvial fan, fluvial and lacustrine deposition in a basin isolated from the Bay of Biscay to the west and the Mediterranean to the east (Garc ıa- Castellanos et al, 2003;Nichols, 2004Nichols, , 2007.…”