Cenozoic sedimentation and exhumation of the foreland basin system preserved in the Precordillera thrust belt (31-32°S), southern central Andes, Argentina

Abstract

Andean retroarc compression associated with subduction and shallowing of the oceanic Nazca plate resulted in thin-skinned thrusting that partitioned and uplifted Cenozoic foreland basin fill in the Precordillera of west-central Argentina. Evolution of the central segment of the Precordillera fold-thrust belt is informed by new analyses of clastic nonmarine deposits now preserved in three intermontane regions between major east directed thrust faults. We focus on uppermost Oligocene-Miocene basin fill in the axial to frontal Precordillera at 31-32°S along the Río San Juan (Albarracín and Pachaco sections) and the flank of one of the leading thrust structures (Talacasto section). The three successions record hinterland construction of the Frontal Cordillera, regional arc volcanism, and initial exhumation of Precordillera thrust sheets. Provenance changes recorded by detrital zircon U-Pb age populations suggest that initial shortening in the Frontal Cordillera coincided with an early Miocene shift from eolian to fluvial accumulation in the adjacent foreland basin. Upward coarsening of fluvial deposits and increased proportions of Paleozoic clasts reflect cratonward (eastward) advance of deformation into the Precordillera and resultant structural fragmentation of the foreland basin into isolated intermontane segments. Apatite (U-Th)/He thermochronometry of basin fill constrains to 12-9 Ma the most probable age of uplift-induced exhumation and cooling of Precordillera thrust sheets. This apparent pulse of exhumation is evident in each succession, suggestive of rapid, large-scale exhumation by synchronous thrusting above a single décollement linking major structures of the Precordillera.

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

“…Neogene evolution of retroarc regions involved continued eastward advance of deformation and foreland basin evolution, with large‐scale shortening accommodated in the frontal thrust belt (Subandean/Santa Bárbara zone) and minor shortening across most of the orogenic interior (Barnes et al, , ; Echavarria et al, ; Ege et al, ; Gubbels et al, ; Kley & Monaldi, ; Lamb, ; Lamb & Hoke, ; Lease et al, ; McQuarrie et al, ; Uba et al, ). Basin evolution was concentrated in foreland regions east of the thrust front, with topographically isolated basins in intermontane settings and the hinterland plateau (Capaldi et al, ; Carrapa et al, ; Coutand et al, ; Horton, , , , ; Horton et al, ; Jordan & Alonso, ; Levina et al, ; Mosolf et al, ; Murray et al, ; Sempere et al, ; Siks & Horton, ; Sobel et al, ; Strecker et al, ; Streit et al, ). Stable isotope data and geomorphic surfaces suggest that major surface uplift of the hinterland plateau at 18–22°S was accomplished from middle Miocene to present (Garzione et al, , ; Hoke et al, ; Jordan et al, ), with a possibility of much earlier surface uplift in the Puna plateau at 24–26°S (Canavan et al, ; Quade et al, ).…”

Cenozoic Shift From Compression to Strike‐Slip Stress Regime in the High Andes at 30°S, During the Shallowing of the Slab: Implications for the El Indio/Tambo Mineral District

“…Tectonics 10.1002/2017TC004608 Fosdick et al, 2015;Japas et al, 2016;Levina et al, 2014;Mardonez et al, 2015;Suriano et al, 2017), and few studies describe structures other than those accommodating Miocene-Holocene contraction along the arc and backarc regions. In yet another interpretation, Charchaflié et al (2007) describe normal faults in the northern sector of the belt, in the Veladero area (29.3°S), generated during the 15 to 10 Ma period, apparently controlling the emplacement of ore deposits.…”

“…On the other hand, Bissig et al () argue that gold deposition occurred several million years after this shortening phase. Indeed, by the time of ore deposition in the metallogenic belt, crustal shortening was focused eastward, in the Argentine Precordillera fold‐and‐thrust belt (Allmendinger & Judge, ; Fosdick et al, ; Japas et al, ; Levina et al, ; Mardonez et al, ; Suriano et al, ), and few studies describe structures other than those accommodating Miocene‐Holocene contraction along the arc and backarc regions. In yet another interpretation, Charchaflié et al () describe normal faults in the northern sector of the belt, in the Veladero area (29.3°S), generated during the 15 to 10 Ma period, apparently controlling the emplacement of ore deposits.…”

Andean Mountain Building and Foreland Basin Evolution During Thin‐ and Thick‐Skinned Neogene Deformation (32–33°S)

“…In this study, we integrate new 40 Ar/ 39 Ar, detrital zircon U‐Pb, and apatite (U‐Th)/He results with published structural, geo/thermochronological, and geophysical data sets to (1) advance the chronostratigraphic and provenance framework of Neogene synorogenic deposits (preserved in the Manantiales Basin at ~32°S; Figures 1b and 2), (2) refine the timing of shortening‐induced exhumation along major thin‐skinned and basement‐involved structures in the retroarc hinterland, and (3) investigate nonemergent structural geometries at ~32°S. Updated correlations with Neogene foreland basin deposits in the Precordillera fold‐thrust belt allow us to reconstruct regional facies, sediment accumulation, and provenance trends (Buelow et al, 2018; Jordan et al, 1996; Levina et al, 2014; Pérez, 2001; Pinto et al, 2018). Thermokinematic modeling is applied to test middle to upper crustal structural interpretations (Almendral et al, 2015; Mora et al, 2015).…”