Tectono-stratigraphic evolution of the Andean Orogen between 31 and 37°S (Chile and Western Argentina)

Abstract

In this classic segment, many tectonic processes, like flat-subduction, terrane accretion and steepening of the subduction, among others, provide a robust framework for their understanding. Five orogenic cycles, with variations in location and type of magmatism, tectonic regimes and development of different accretionary prisms, show a complex evolution. Accretion of a continental terrane in the Pampean cycle exhumed lower to middle crust in Early Cambrian. The Ordovician magmatic arc, associated metamorphism and foreland basin formation characterized the Famatinian cycle. In Late Devonian, the collision of Chilenia and associated high-pressure/low-temperature metamorphism contrasts with the late Palaeozoic accretionary prisms. Contractional deformation in Early to Middle Permian was followed by extension and rhyolitic (Choiyoi) magmatism. Triassic to earliest Jurassic rifting was followed by subduction and extension, dominated by Pacific marine ingressions, during Jurassic and Early Cretaceous. The Late Cretaceous was characterized by uplift and exhumation of the Andean Cordillera. An Atlantic ingression occurred in latest Cretaceous. Cenozoic contraction and uplift pulses alternate with Oligocene extension. Late Cenozoic subduction was characterized by the Pampean flat-subduction, the clockwise block tectonic rotations in the normal subduction segments and the magmatism in Payenia. These processes provide evidence that the Andean tectonic model is far from a straightforward geological evolution.

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

“…Although provenance data show continued derivation from both the arc and craton (Balgord & Carrapa, ; Mescua et al, ; Tunik et al, ), a sharp increase in sediment accommodation accompanied by thrust‐related growth strata and focused exhumation demonstrate the contractional nature of the episode (Fennell et al, ; Folguera, Bottesi, et al, ; Horton & Fuentes, ; Horton et al, ). This initial foreland basin is defined by proximal clastic deposits in the Central Valley (Las Chilcas Formation; Boyce, ; Charrier et al, ) and the Principal Cordillera (Brownish‐Red Clastic Unit; Charrier et al, , ). Late Cretaceous shortening coincided with eastward advance of arc magmatism attributable to subduction shallowing (Charrier et al, ; Folguera & Ramos, ; Spagnuolo, Folguera, et al, ).…”

“…This paper examines along‐strike (north‐south) and across‐strike (east‐west) variations in the Cretaceous‐Cenozoic geologic history of the central to southern Andes in an effort to emphasize potential temporal and spatial discrepancies in tectonic regimes for high‐shortening versus low‐shortening segments of the orogenic belt. Previous syntheses have focused on the magnitude and timing of deformation, episodic or cyclical changes in deformation and magmatism (including geochemical evolutionary trends), fluctuations in the geometry of the subducting slab, and the timing and mechanisms of surface uplift (e.g., Allmendinger et al, ; Barnes & Ehlers, ; Charrier et al, , ; DeCelles et al, ; Giambiagi, Mescua, et al, ; Garzione et al, ; Gianni et al, ; Haschke et al, , ; Kay et al, ; Kay & Coira, ; Oncken et al, ; Ramos et al, ; Ramos, , ; Ramos et al, ; Ramos & Kay, ; Rojas Vera et al, ; Trumbull et al, ). The goal here is not to replicate these valuable studies but to provide an integrated view of the Cretaceous‐Cenozoic records of (1) deformation (in terms of horizontal shortening, extension, or stasis), (2) magmatism (in terms of arc activity, arc cessation, or extension‐related within‐plate magmatism), and (3) sedimentary basin evolution (in terms of basin‐forming processes in foreland, hinterland, and forearc settings).…”

Structure and tectonics of the central Chilean margin (31°–33°S): implications for subduction erosion and shallow crustal seismicity

“…Ota et al 1995), dune formation and sand barred estuaries of major rivers (Heinze 2003), river incision, and uplifted and tilted strandlines (e.g. Charrier et al 2007). …”

Geodynamic processes in the Andes of Central Chile and Argentina: an introduction

“…The tectonic style of the different morphostructural units comprising the orogen is strongly influenced by pre-Andean structures, especially those developed during the Late Devonian -early Carboniferous Chanic Orogeny and the late Carboniferous-early Permian San Rafael Orogeny of the Gondwanan orogenic cycle (Ramos 1988;Mpodozis & Ramos 1989;Giambiagi et al 2011Giambiagi et al , 2014aHeredia et al 2012). The first chapter by Charrier et al (2014) presents a review of the major geological features and tectonic events that occurred in the Andean region between 318S and 378S since early Phanerozoic time and prior to the Neogene Andean deformation. The authors synthesize current knowledge of pre-Andean orogenic cycles, as well as the influence of these cycles over Andean Orogeny since Neogene time, while emphasizing the importance of the relationship between magmatism, metamorphism, sedimentation and deformation.…”