Neogene landscape evolution in the Andes of north-central Chile between 28 and 32°S: interplay between tectonic and erosional processes

Rodríguez, M. H.; Aguilar, Germán; Urresty, Constanza; Charrier, Reynaldo

doi:10.1144/sp399.15

Cited by 11 publications

(16 citation statements)

References 67 publications

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“…Although the uplift of the northern sector may have occurred earlier than in the central and southern sectors, the topography seems less evolved. The northern catchments present large remnants of perched Miocene palaeosurfaces (Bissig et al 2002;Aguilar et al 2011;Rodríguez et al 2014). The averaged erosion rate calculated from the incision of these surfaces is similar to the millennial and decadal erosion rates, which is consistent with a slow increase in the erosion rate and a long response time of erosion to surface uplift (Aguilar et al 2011.…”

Section: Discussionsupporting

confidence: 58%

Erosion in the Chilean Andes between 27°S and 39°S: tectonic, climatic and geomorphic control

Carretier

Tolorza

Rodríguez

et al. 2014

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The effect of mean precipitation rate on erosion is debated. Three hypotheses may explain why the current erosion rate and runoff may be spatially uncorrelated: (1) the topography has reached a steady state for which the erosion rate pattern is determined by the uplift rate pattern;(2) the erosion rate only depends weakly on runoff; or (3) the studied catchments are experiencing different transient adjustments to uplift or to climate variations. In the Chilean Andes, between 278S and 398S, the mean annual runoff rates increase southwards from 0.01 to 2.6 m a 21 but the catchment averaged rates of decadal erosion (suspended sediment) and millennial erosion ( 10 Be in river sand) peak at c. 0.25 mm a 21 for runoff c. 0.5 m a 21 and then decrease while runoff keeps increasing. Erosion rates increase non-linearly with the slope and weakly with the square root of the runoff. However, sediments trapped in the subduction trench suggest a correlation between the current runoff pattern and erosion over millions of years. The third hypothesis above may explain these different erosion rate patterns; the patterns seem consistent with, although not limited to, a model where the relief and erosion rate have first increased and then decreased in response to a period of uplift, at rates controlled by the mean precipitation rate.

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Section: Discussionsupporting

confidence: 58%

Erosion in the Chilean Andes between 27°S and 39°S: tectonic, climatic and geomorphic control

Carretier

Tolorza

Rodríguez

et al. 2014

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“…Neogene tectonic activity during this phase resulted in the generation of major and secondary contractional structures that accommodated major horizontal shortening, at various stratigraphic levels, favoring the progress of a more spatially distributed deformation and a large volume of synorogenic materials. Even the western flank of the Andes was active, as revealed by the valley bottom thermochronology results presented as well as the Miocene surface uplift of pediplains between 29° and 30°S (Rodríguez et al, ).…”

Section: Discussion and Tectonic Implicationsmentioning

confidence: 93%

Thermochronologic Evidence for Late Eocene Andean Mountain Building at 30°S

et al. 2017

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The Andes between 28° and 30°S represent a transition between the Puna‐Altiplano Plateau and the Frontal/Principal Cordillera fold‐and‐thrust belts to the south. While significant early Cenozoic deformation documented in the Andean Plateau, deciphering the early episodes of deformation during Andean mountain building in the transition area is largely unstudied. Apatite fission track (AFT) and (U‐Th‐Sm)/He (AHe) thermochronology from a vertical and a horizontal transect reveal the exhumation history of the High Andes at 30°S, an area at the heart of this major transition. Interpretation of the age‐elevation profile, combined with inverse thermal modeling, indicates that the onset of rapid cooling was underway by ~35 Ma, followed by a significant decrease in cooling rate at ~30–25 Ma. AFT thermal models also reveal a second episode of rapid cooling in the early Miocene (~18 Ma) related to rock exhumation to its present position. Low exhumation between the rapid cooling events allowed for the development of a partial annealing zone. We interpret the observed Eocene rapid exhumation as the product of a previously unrecognized compressive event in this part of the Andes that reflects a southern extension of Eocene orogenesis recognized in the Puna/Altiplano. Renewed early‐Miocene exhumation indicates that the late Cenozoic compressional stresses responsible for the main phase of uplift of the South Central Andes also impacted the core of the range in this transitional sector. The major episode of Eocene exhumation suggests the creation of significant topographic relief in the High Andes earlier than previously thought.

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“…Interplay between tectonic and erosional processes is also brought to the forefront by Rodríguez et al (2014). They combine geomorphological analysis of palaeo-surfaces and U -Pb zircon geochronology of overlying tuffs to reconstruct the Neogene landscape evolution of north-central Chile (28-328S).…”

Section: External Geodynamics and Landscape Evolutionmentioning

confidence: 99%

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

Sepúlveda

Giambiagi

Moreiras

et al. 2014

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The Andes, the world's largest non-collisional orogen, is considered the paradigm for geodynamic processes associated with the subduction of an oceanic plate below a continental plate margin. In the framework of UNESCO-sponsored IGCP 586-Y project, this Special Publication includes state-of-the-art reviews and original articles from a range of Earth Science disciplines that investigate the complex interactions of tectonics and surface processes in the subductionrelated orogen of the Andes of central . This introduction provides the geological context of the transition from flat slab to normal subduction angles, where this volume is focused, along with a brief description of the individual contributions ranging from internal geodynamics and tectonics, Quaternary tectonics and related geohazards, to landscape evolution of this particular segment of the Andes.Convergent continental margins are one of the firstorder expressions of the movement of Earth's tectonic plates atop a convecting mantle. The topography of convergent margins is due to the interactions of rock uplift, climate and surface processes that are dominantly driven by upper crustal and internal lithospheric deformation as well as erosional processes (e.g. Molnar & Lyon-Caen 1988;Beaumont et al. 2004;Whipple & Meade 2006). The Andes of central Chile and Argentina (c. 32 -368S, Figs 1 & 2) straddle a potentially important transition in geodynamic boundary conditions imposed on the upper plate: a drastic change in the geometry of the subducting Nazca plate from 'flat' to normal subduction angles, from c. 5-108 to 308 (Cahill & Isacks 1992; Fig. 1). This segment of the Andes is therefore a particularly suitable setting to evaluate the interplay between constructive deep mechanisms, resulting in rock uplift and lateral expansion of the Andes, and the mechanisms of exhumation and erosion that shape the landscape in an active, convergent margin.The Central Andes are composed of different morphostructural units (from west to east; Figs 1 & 2): the Chilean Coastal Cordillera, the Principal Cordillera (spanning Chile and Argentina), the Frontal Cordillera, the Argentine Precordillera and the Pampean Ranges (Jordan et al. 1983). Although previous studies attempt to constrain the magnitudes of orogenic shortening for each morphostructural unit, limited amounts of geochronology complicate attempts to constrain more tightly the rates of shortening and topographic uplift. There are several outstanding questions regarding the interplay between deep and surface processes in the development of the Andean Orogen over different timescales, as follows. † What is the nature of the interaction between tectonic and surface processes in this sector of the Andes? In particular, are surface and tectonic processes part of a strongly coupled system? † What control does the geometry of the subducting slab exert over the timing and style of deformation in the South American plate? † How do deformation and denudation evolve in space and time? Are there differences between ...

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Neogene landscape evolution in the Andes of north-central Chile between 28 and 32°S: interplay between tectonic and erosional processes

Cited by 11 publications

References 67 publications

Erosion in the Chilean Andes between 27°S and 39°S: tectonic, climatic and geomorphic control

Erosion in the Chilean Andes between 27°S and 39°S: tectonic, climatic and geomorphic control

Thermochronologic Evidence for Late Eocene Andean Mountain Building at 30°S

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

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