Middle Miocene climatic change in the Atacama Desert, northern Chile: Evidence from supergene mineralization at La Escondida

Alpers, Charles N.; Brimhall, George H.

doi:10.1130/0016-7606(1988)100<1640:mmccit>2.3.co;2

Cited by 327 publications

(237 citation statements)

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“…For these reasons, geomorphic surfaces in the Atacama Desert have variable ages that depend on their last exposure to runoff from the east (e.g., Alpers and Brimhall, 1988;Hartley and Chong, 2002;Dunai et al, 2005;Evenstar et al, 2009). The Cordillera de la Costa (Fig.…”

Section: Regional Settingmentioning

confidence: 99%

Origin and development of theater-headed valleys in the Atacama Desert, northern Chile: Morphological analogs to martian valley networks

Irwin

Tooth

Craddock

et al. 2014

Icarus

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a b s t r a c tUnderstanding planetary landforms, including the theater-headed valleys (box canyons) of Mars, usually depends on interpreting geological processes from remote-sensing data without ground-based corroboration. Here we investigate the origin and development of two Mars-analog theater-headed valleys in the hyperarid Atacama Desert of northern Chile. Previous workers attributed these valleys to groundwater sapping based on remote imaging, topography, and publications on the local geology. We evaluate groundwater sapping and alternative hypotheses using field observations of characteristic features, strength measurements of strata exposed in headscarps, and estimates of ephemeral flood discharges within the valleys. The headscarps lack evidence of recent or active seepage weathering, such as spring discharge, salt weathering, alcoves, or vegetation. Their welded tuff caprocks have compressive strengths multiple times those of the underlying epiclastic strata. Flood discharge estimates of cubic meters to tens of cubic meters per second, derived using the Manning equation, are consistent with the size of transported clasts and show that the ephemeral streams are geomorphically effective, even in the modern hyperarid climate. We interpret that headscarp retreat in the Quebrada de Quisma is due to ephemeral flood erosion of weak Miocene epiclastic strata beneath a strong welded tuff, with erosion of the tuff facilitated by vertical jointing. The Quebrada de Humayani headscarp is interpreted as the scar of a giant landslide, maintained against substantial later degradation by similar strong-over-weak stratigraphy. This work suggests that theater-headed valleys on Earth and Mars should not be attributed by default to groundwater sapping, as other processes with lithologic and structural influences can form theater headscarps.Published by Elsevier Inc.

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Section: Regional Settingmentioning

confidence: 99%

Origin and development of theater-headed valleys in the Atacama Desert, northern Chile: Morphological analogs to martian valley networks

Irwin

Tooth

Craddock

et al. 2014

Icarus

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“…The Atacama Desert is one of the oldest and driest deserts on the Earth today (e.g., ref. 16) (Fig. 3).…”

mentioning

confidence: 99%

Emergence of social complexity among coastal hunter-gatherers in the Atacama Desert of northern Chile

Marquet

Santoro

Latorre

et al. 2012

Proc. Natl. Acad. Sci. U.S.A.

125

101

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The emergence of complex cultural practices in simple huntergatherer groups poses interesting questions on what drives social complexity and what causes the emergence and disappearance of cultural innovations. Here we analyze the conditions that underlie the emergence of artificial mummification in the Chinchorro culture in the coastal Atacama Desert in northern Chile and southern Peru. We provide empirical and theoretical evidence that artificial mummification appeared during a period of increased coastal freshwater availability and marine productivity, which caused an increase in human population size and accelerated the emergence of cultural innovations, as predicted by recent models of cultural and technological evolution. Under a scenario of increasing population size and extreme aridity (with little or no decomposition of corpses) a simple demographic model shows that dead individuals may have become a significant part of the landscape, creating the conditions for the manipulation of the dead that led to the emergence of complex mortuary practices.climate variability | coastal desert | cultural evolution

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“…In the Puna, aridification is commonly linked with the onset of internal drainage and the appearance of evaporites between 24 and 15 Ma (e.g., Alonso et al 1991;Vandervoort et al 1995), although arid environments may have existed already in the Eocene (Adelmann 2001). In line with these observations is the termination of supergene alteration and copper-sulfide enrichment at about 24°S in the Atacama desert of northern Chile between 14 and 8.7 Ma (Alpers and Brimhall 1988), at 27°10' S at 13.3 Ma, and at 27°47' S at 13.5 Ma (Sillitoe et al 1991), in the volcanic arc immediately west of the Puna. Furthermore, based on the analysis of drainage patterns between 18 and 22°S, Hoke et al (2004) suggest that a changeover to hyper-arid climate conditions may have occurred along the western slopes of the Andes between about 10 and 5.8 Ma.…”

Section: Tertiary Climate Characteristicssupporting

confidence: 62%

“…Within the Salar de Hombre Muerto area at 25°S, evaporite deposition and internal drainage was established by 15 ± 1.2 Ma, and perhaps as early as the Oligocene (Alonso et al 1991;Vandervoort et al 1995). In the same region the termination of supergene copper mineralization at 14.7 Ma provides a minimum age for the time when hyper-aridity was established (Alpers and Brimhall 1988). Finally, in the Sierra Chango Real along the present Puna margin at about 27°S (Fig.…”

Section: Processes Of Relief Reduction the Role Of Internal Drainagementioning

confidence: 99%

Tectonics, Climate, and Landscape Evolution of the Southern Central Andes: the Argentine Puna Plateau and Adjacent Regions between 22 and 30°S

et al.

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Middle Miocene climatic change in the Atacama Desert, northern Chile: Evidence from supergene mineralization at La Escondida

Cited by 327 publications

References 0 publications

Origin and development of theater-headed valleys in the Atacama Desert, northern Chile: Morphological analogs to martian valley networks

Origin and development of theater-headed valleys in the Atacama Desert, northern Chile: Morphological analogs to martian valley networks

Emergence of social complexity among coastal hunter-gatherers in the Atacama Desert of northern Chile

Tectonics, Climate, and Landscape Evolution of the Southern Central Andes: the Argentine Puna Plateau and Adjacent Regions between 22 and 30°S

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