Neogene tectonostratigraphic history of the southern Neuquén basin (39°–40°30′S, Argentina): implications for foreland basin evolution

Abstract

Although the Neuquén basin in Argentina forms a key transitional domain between the south‐central Andes and the Patagonian Andes, its Cenozoic history is poorly documented. We focus on the sedimentologic and tectonic evolution of the southern part of this basin, at 39–40°30′S, based on study of 14 sedimentary sections. We provide evidence that this basin underwent alternating erosion and deposition of reworked volcaniclastic material in continental and fluvial settings during the Neogene. In particular, basement uplift of the Sañico Massif, due to Late Miocene–Pliocene intensification of tectonic activity, led to sediment partitioning in the basin. During this interval, sedimentation was restricted to the internal domain and the Collon Cura basin evolved towards an endorheic intermontane basin. From stratigraphic interpretation, this basin remained isolated 7–11 Myr. Nevertheless, ephemeral gateways seem to have existed, because we observe a thin succession downstream of the Sañico Massif contemporaneous with the Collon Cura basin‐fill sequence. Comparisons of stratigraphic, paleoenvironmental and tectonic features of the southern Neuquén basin with other foreland basins of South America allow us to classify it as a broken foreland with the development of an intermontane basin from Late Miocene to Late Pliocene. This implies a thick‐skinned structural style for this basin, with reactivation of basement faults responsible for exhumation of the Sañico Massif. Comparison of several broken forelands of South America allows us to propose two categories of intermontane basins according to their structural setting: subsiding or uplifted basins, which has strong implications on their excavation histories.

The fracture network, a proxy for mesoscale deformation: Constraints on layer parallel shortening history from the Malargüe fold and thrust belt, Argentina

“…In our case, the distance to the front is not a controlling factor for fracture development as the MFTB does not evolve as a critical coulomb wedge controlled by dynamics of a basal décollement level leading to regular frontal accretion and strain propagation toward the foreland. Rather its evolution is controlled by strain localization along preexisting extensional anisotropies triggering basement thrusting and intramontane basin formation [Huyghe et al, 2014;Ramos et al, 2014]. As evidenced by cross sections, deformation is compartmentalized in a Laramide style leading to large distribution of deformation in the lithosphere and propagation far from the orogenic front (San Rafael block; Figure 1).…”

Tectonic Regimes of the Central and Southern Andes: Responses to Variations in Plate Coupling During Subduction

“…In most forearc regions, geomorphic and seismic observations indicate a heterogenous pattern of low‐magnitude neotectonic deformation involving shortening along the western Andean slope (inner forearc) but focused extension along the Pacific coast (outer forearc) (Adam & Reuther, ; Allmendinger & González, ; Hall et al, ; Veloza et al, ). In the southern Andes, conflicting evidence of Quaternary retroarc contractional versus extensional deformation at 35–40°S (Cobbold & Rossello, ; Folguera et al, , ; Guzmán et al, ; Huyghe et al, ; Messager et al, ; Tapia et al, ) along with sparse stress data farther south in Patagonia are possible manifestations of relatively neutral to low‐stress conditions with negligible net strain (e.g., Cobbold et al, ; Folguera, Gianni, et al, ; Marotta et al, ).…”

“…During the Neogene, retroarc shortening in a narrow fold‐thrust system was governed by reactivation of earlier Cenozoic extensional structures, with only 10–20 km of shortening and minor deformation in distal regions of the broken foreland (Giacosa et al, ; Giacosa & Heredia, ; Orts et al, , ; Savignano et al, ). Associated wedge‐top and foreland basin development is marked by the Ñirihuau and Collón‐Curá Basins, including documented growth strata along associated thrust faults (Bechis et al, ; Bilmes et al, ; Echaurren et al, ; García Morabito & Ramos, ; Giacosa et al, ; Huyghe et al, ; Orts et al, ; Paredes et al, ; M. Ramos et al, ). In the arc to forearc region, dextral offset along the north striking Liquiñe‐Ofqui fault zone initiated by late Miocene time, as a product of strain partitioning during oblique subduction and further modification by ridge collision during Pliocene‐Quaternary time (Cembrano et al, , ; Thomson, ).…”

The North Patagonian orogenic front and related foreland evolution during the Miocene, analyzed from synorogenic sedimentation and U/Pb dating (∼42°S)

“…1) (Giacosa y Heredia, 2000, 2004Ramos et al, 2011;Orts et al, 2012;Bilmes et al, 2013;Bechis et al, 2014a;Huyghe et al, 2014). These works have described and analyzed synorogenic sequences of the Miocene Ñirihuau Basin, located next to the orogenic front area in an eastern broken foreland system.…”