Massive middle Miocene gypsic paleosols in the Atacama Desert and the formation of the Central Andean rain-shadow

Rech, Jason A.; Currie, Brian S.; Jordan, Teresa E.; Riquelme, Rodrigo; Lehmann, Sophie B.; Kirk-Lawlor, Naomi E.; Li, Shanying; Gooley, Jared T.

doi:10.1016/j.epsl.2018.10.040

Cited by 51 publications

(53 citation statements)

References 64 publications

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“…1,500 m surface uplift documented by Barke and Lamb (2006). Although there is clear evidence for a rain shadow by 15 Ma from the Central Andes (Rech et al, 2019), we acknowledge that the rainfall-elevation relationship may have changed during the posterior rise of the Andes (Ehlers & Poulsen, 2009;Poulsen et al, 2010), with an intensification of the monsoon, so that the estimated elevation of 7.9 Ma may be a minimum. Nevertheless, the general consistency between the model predictions and the sediment accumulation rates supports the interpretation of Uba et al (2007).…”

Section: Comparison With Examples Of Climate Tectonics and Erosionmentioning

confidence: 81%

Influence of orographic precipitation on the topographic and erosional evolution of mountain ranges

2020

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The influence of climate on mountain denudation has been the topic of an intense debate for two decades. This debate partly arises from the covariation of rainfall and topography during the growth of mountain ranges, both of which influence denudation. However, the denudational response of this co-evolution is poorly understood. Here, we use a landscape evolution model where the rainfall evolves according to a prescribed rainfall-elevation relationship. This relationship is a bell curve defined by a rainfall base level, a rainfall maximum and a width around the rainfall peak elevation. This is a firstorder model that fits a large range of orographic rainfall data at the ca. 1-km spatial scale. We carried out simulations of an uplifting block with an alluvial apron, starting from an initially horizontal surface, and testing different rainfall-elevation relationships. We find Highlights 1576 | EAGE ZAVALA et AL.

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Section: Comparison With Examples Of Climate Tectonics and Erosionmentioning

confidence: 81%

Influence of orographic precipitation on the topographic and erosional evolution of mountain ranges

2020

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“…The onset of Antarctic Bottom Water formation, the growth of the East Antarctic Ice Sheet and the resulting intensification of cold water upwelling along the Pacific Coast during the middle Miocene possibly contributed to the increasing aridity on the western side of the Andes (Houston and Hartley, 2003, and references therein). Sedimentologic, geomorphologic, pedogenic and isotopic data suggest that this change to hyperaridity occurred in the middle Miocene at about 12 Ma (Riquelme et al, 2007;Nalpas et al, 2008;Evenstar et al, 2009;Rech et al, 2010;Jordan et al, 2014;Rech et al, 2019) and was interrupted by several arid and semi-arid stages in the higher elevated regions of the western Andean margin (Sáez et al 2012;Jordan et al, 2014). The middle Miocene also marks the onset of deep canyon incision on the western Andean slope in northern Chile that are either linked to these climatic changes (García et al, 2011;Cooper et al, 2016) or to surface uplift related to westward tilting of the forearc (e.g., Farías et al, 2005;García and Hérail, 2005;Hoke et al, 2007).…”

Section: Paleoclimate Of the Central Andesmentioning

confidence: 99%

The relationships between tectonics, climate and exhumation in the Central Andes (18–36°S): Evidence from low-temperature thermochronology

Stalder

Herman

Fellin

et al. 2020

Earth-Science Reviews

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The Central Andes between 18°S and 36°S latitude strike north-south for 2000 km along the Chilean subduction margin, cross several climate zones from hyperarid to humid and exhibit mean elevations in excess of 4000 m.a.s.l. Here, we investigate the relationships between tectonics, climate and exhumation by inverting low-temperature thermochronological data compiled from the literature (824 ages from 549 samples) and new data (238 ages from 146 samples) to quantify the exhumation rate history of the Central Andes since 80 Ma. Our inferred exhumation rates west of the drainage divide and between 18 and 32°S did not exceed 0.25 km/Ma. Such low exhumation rates are consistent with low shortening rates and arid conditions in this region. Local pulses of exhumation occurred only during the Eocene as 2 response to active deformation and during the Miocene, probably as response to uplift of the western Andean slope. East of the drainage divide between 18 and 28°S, the observed exhumation pattern reflects the onset and eastward propagation of deformation. Here, exhumation occurred locally since the middle-to-late Eocene in the Eastern Cordillera and the Altiplano-Puna and subsequently affected larger parts of these regions and the northwestern Sierra Pampeanas during the Oligocene. In the early Miocene (~20 Ma), the Interandean zone started exhuming and at 12-10 Ma exhumation propagated into the Subandean zone. Enhanced shortening rates and intensified precipitation along the eastern deformation front associated with the onset of the South American Monsoon led to increased exhumation rates in the eastern Interandean and the Subandean zones in the Plio-Pleistocene (0.6 km/Ma). Higher Pleistocene exhumation rates are also observed in the northern Sierra Pampeanas (1.5 km/Ma) that can be related to rock uplift along steep reverse faults coupled with high precipitation. South of 32°S on the western side, exhumation rates in the Principal Cordillera increased from ca. 0.25 km/Ma in the Miocene to rates locally exceeding 2 km/Ma in the Pleistocene. Whereas the tectonic regime in the southern Principal Cordillera remained unchanged since the late Miocene, these higher rates are likely associated with enhanced erosion resulting from intensified Pleistocene precipitation and glacial growth in this region, reinforced by isostatic rock uplift and active tectonics. Our study shows that the onset of exhumation correlates mainly with the initiation of horizontal shortening and crustal thickening, whereas the magnitude of exhumation is largely set by the amount of precipitation and glacial erosion and by the style of deformation, which is controlled by inherited structures and the amount of sediments in the foreland. In the following, we present new low-temperature thermochronological data (238 ages) that we complement with literature data (824 ages) to constrain the exhumation rate history of the Andean mountain belt at large temporal (Ma) and spatial scales (18 to 36°S). We focus on apatite and zircon fission track (AFT and ZFT, respe...

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“…2). The climate has been arid to semi-arid since at least the late Jurassic (Hartley et al, 2005), arid since the late Oligocene and predominantly hyperarid since the mid Miocene (Evenstar et al, 2009, Jordan et al, 2014, Evenstar et al, 2017, Rech et al, 2019.…”

Section: Study Area Climatementioning

confidence: 99%

Using spatial patterns of fluvial incision to constrain continental-scale uplift in the Andes

Evenstar

Mather

Hartley

2020

Global and Planetary Change

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Geomorphic archives, particularly longitudinal river profiles, are increasingly used as a proxy to reconstruct uplift rates in mountainous regions. Within the Atacama Desert, Northern Chile, slow, long-term erosion creates exceptional preservation of fluvial and alluvial surfaces. This enables river incision patterns to be used on a continental-scale (>250 km) along the western margin of the Andes (18°00'S to 20°15'S) and over a time frame from Miocene to Present day. The data show marked compartmentalisation of fluvial system behaviour with changes in incision rates from south to north creating 3 distinctly different regions. Within these different sectors, incision rates are broadly consistent between rivers suggesting a regional rather than a river specific control on rates. In Sector 1 (18°05'S to 19°20'S) the fluvial systems are exorheic with a terminal base level (the lowest base level to which the river system can erode) in the Pacific Ocean and span the Coastal Cordillera, Longitudinal Valley, Precordillera and western edge of the Western Cordillera. This constrains the total uplift over these regions to a minimum of 1200 m in 11 Myr with incision rates of ~200-120 m/Myr consistent with rapid but sustained uplift of the Andes in the Late Miocene. In Sector 2 (19°20'S to 19°50'S), to the immediate south, the rivers are shorter and terminate in the Longitudinal Valley, spanning only the Longitudinal Valley, Precordillera and the western edge of the Western Cordillera with lower incision rates of 100-50 m/Myr. Comparison of incision rates between Sector 1 and 2 can constrain the uplift of the Coastal Cordillera to 60m/Myr which is in keeping with previous studies from the region. In southernmost Sector 3 (19°50'S to 20°10'S), the fluvial systems terminate in the Longitudinal Valley and span only the Longitudinal Valley and eastern part of the Precordillera with low incision rates of 50 to 25 m/Myr. Differences between Sectors 2 and 3 are attributable to drainage loss by tectonic beheading of catchments through uplift of the Cordillera de Domeyko fault system, placing a minimum constrain on uplift in this region of 50 to 25 m/Myr. This study demonstrates the applicability of large-scale fluvial archives to access not just the timing of uplift on a continental scale, but also the relative uplift of individual tectonic provinces.

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Massive middle Miocene gypsic paleosols in the Atacama Desert and the formation of the Central Andean rain-shadow

Cited by 51 publications

References 64 publications

Influence of orographic precipitation on the topographic and erosional evolution of mountain ranges

Influence of orographic precipitation on the topographic and erosional evolution of mountain ranges

The relationships between tectonics, climate and exhumation in the Central Andes (18–36°S): Evidence from low-temperature thermochronology

Using spatial patterns of fluvial incision to constrain continental-scale uplift in the Andes

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