A General Overview of Gondwana Landscapes in Argentina

Rabassa, Jorge; Carignano, Claudio; Cioccale, Marcela

doi:10.1007/978-94-007-7702-6_9

Cited by 21 publications

(18 citation statements)

References 24 publications

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“…As a consequence, regional planation processes took place most likely during the Lower-Middle Jurassic and/or during the Late Cretaceous, although data presented here cannot discriminate if major erosion surfaces are diachronous in time, as suggested by Carignano (1999) and Rabassa et al (2010Rabassa et al ( , 2014. AHe ages indicate that both time intervals contributed to the exhumation of the sampled area.…”

Section: Development Of Planation Surfacesmentioning

confidence: 54%

“…González Díaz (1981) andCriado Roque et al (1981) considered them as a formerly continuous and essentially synchronous surface, which was uplifted and disrupted into several minor surfaces and juxtaposed by faults during the Andean Orogeny. Alternatively, Carignano (1999) and Rabassa et al (2010Rabassa et al ( , 2014 suggested that erosional paleosurfaces represent diachronous planation episodes, which are confined to different topographic levels and separated by topographic scarps. Based on field observations, the latter authors propose that paleosurface ages should range between Late Paleozoic and Paleogene.…”

Section: Geological and Morphotectonic Settingmentioning

confidence: 99%

“…Hence, the evolution of these ranges since the late Paleozoic is still a matter of ongoing debate (e.g., Jordan et al, 1989;Carignano, 1999;Löbens et al, 2011;Dávila and Carter, 2013;Enkelmann et al, 2014;Rabassa et al, 2014).…”

Section: Introductionmentioning

confidence: 99%

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Exhumation history and landscape evolution of the Sierra de San Luis (Sierras Pampeanas, Argentina) - new insights from low - temperature thermochronological data

Bense

Costa

Oriolo

et al. 2017

andgeo

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ABSTRACT. This paper presents low-temperature thermochronological data and K-Ar fault gouge ages from the Sierra de San Luis in the Eastern Sierras Pampeanas in order to constrain its low-temperature thermal evolution and exhumation history. Thermal modelling based on (U-Th)/He dating of apatite and zircon and apatite fission track dating point to the Middle Permian and the Triassic/Early Jurassic as main cooling/exhumation phases, equivalent to ca. 40-50% of the total exhumation recorded by the applied methods. Cooling rates are generally low to moderate, varying between 2-10 °C/Ma during the Permian and Triassic periods and 0.5-1.5 °C/Ma in post-Triassic times. Slow cooling and, thus, persistent residence of samples in partial retention/partial annealing temperature conditions strongly influenced obtained ages. Thermochronological data indicate no significant exhumation after Cretaceous times, suggesting that sampled rocks were already at or near surface by the Cretaceous or even before. As consequence, Cenozoic cooling rates are low, generally between 0.2-0.5 °C/Ma which is, depending on geothermal gradient used for calculation, equivalent to a total Cenozoic exhumation of 0.6-1.8 km. K-Ar fault gouge data reveal long-term brittle fault activity. Fault gouge ages constrain the end of ductile and onset of brittle deformation in the Sierra de San Luis to the Late Carboniferous/Early Permian. Youngest K-Ar illite ages of 222-172 Ma are interpreted to represent the last illite formation event, although fault activity is recorded up to the Holocene. RESUMEN. Historia de la exhumación y evolución del paisaje de la sierra de San Luis (Sierras Pampeanas, Argentina)-nuevas perspectivas a partir de datos termocronológicos de baja temperatura. Esta contribución presenta datos de termocronología de baja temperatura y edades de illitas generadas en zonas de fallas de la sierra de San Luis, en las Sierras Pampeanas Orientales de Argentina, con el propósito de aportar al conocimiento de la historia de su exhumación y evolución termal de baja temperatura. El modelado termal basado en dataciones de (U-Th)/He, apatita, circón y trazas de fisión sugiere que las principales fases de exhumación y enfriamiento ocurrieron durante el Pérmico medio y Triásico/Jurásico inferior, contribuyendo con aproximadamente 40-50% de la exhumación total registrada por los métodos utilizados. Las tasas de enfriamiento son, en general, bajas a moderadas, variando entre 2-10 °C/Ma durante el Pérmico y Triásico y 0,5-1,5 °C/Ma después del este último período. El lento enfriamiento y la persistente residencia de las muestras analizadas en condiciones térmicas de retención parcial (partial annealing) ha influenciado notoriamente las edades obtenidas. Los datos termocronológicos indican que no ha habido una exhumación 276 Exhumation history and LandscapE EvoLution of thE siErra dE san Luis (siErras pampEanas, argEntina)... significativa después del Cretácico o incluso antes. Consecuentemente, las tasas de enfriamiento durante el Cenozoico, son bajas, ge...

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Section: Development Of Planation Surfacesmentioning

confidence: 54%

Section: Geological and Morphotectonic Settingmentioning

confidence: 99%

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Exhumation history and landscape evolution of the Sierra de San Luis (Sierras Pampeanas, Argentina) - new insights from low - temperature thermochronological data

Bense

Costa

Oriolo

et al. 2017

andgeo

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“…At that time, it is believed that tropical to subtropical conditions extended perhaps as far south as 70° S. This is attributed to a unique ocean-current circulation at that time, which resulted in a large transfer of heat from the equatorial zones to the poles (Frakes, 1979). During the Cretaceous, the equatorial zone was heated much more intensely than at present not only because of the increase in the atmospheric level of CO 2 , which resulted in rising global temperatures at that time, but also because the huge extension of the Pacific Ocean at low latitudes at that time would have lowered the global albedo, strongly increasing the heat capacity of the oceans and thereby influencing the Earth's heat reservoir at that time (Rabassa, 2014).…”

Section: Discussionmentioning

confidence: 99%

Evidences of Widespread Cretaceous Deep Weathering and Its Consequences: A Review

Bata¹

2016

ESR

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This study highlights the effect of the Cretaceous greenhouse climate on weathering processes. Atmospheric CO2 level was relatively higher in the Cretaceous than it was in both the Jurassic and the Cenozoic. Consequently, temperature and humidity were higher in the Cretaceous than in the Jurassic and the Cenozoic. The interaction among the high levels of atmospheric CO2, extreme global warmth, and humidity in the Cretaceous resulted in widespread deep weathering. Cretaceous palaeo-weathering profiles are observed to occur at higher palaeolatitudes relative to the Jurassic and Cenozoic palaeo-weathering profiles. This implies the upward warming of the Cretaceous palaeolatitude, consistent with palaeotemperature estimates for the Cretaceous. The present thickness of weathering profiles in some selected tropical zones is approximately 200 m. During the greenhouse climatic condition in the Cretaceous, the thickness of weathering profiles at those areas could have been up to 4–5 times the present value. This suggests that many sediments were produced from the Cretaceous weathering events.

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“…A varied morpho-structural context shapes up the landforms of the basement landscape, where the primary characteristics of the rocks such as mineralogy, texture, and structure determine their weathering and erosion, and their later transformation into regolith or saprolite Aragón et al 2005;Rabassa et al 2014). In this chapter, the term "saprolite" is restricted to the whole volume of in situ weathered rock, whereas the term "regolith" applies to all overlying materials (including, loess, alluvium), that is, every mineral and rocky materials between fresh rock and fresh air, and it may involve also the saprolite, if it is still in situ (C. Ollier, 2012, personal communication).…”

Section: Introductionmentioning

confidence: 99%

Paleo-landscapes of the Northern Patagonian Massif, Argentina

Aguilera

Rabassa

Aragón

2014

Gondwana Landscapes in Southern South America

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The dominant geomorphological unit of the Northern Patagonian Massif landscape is a regional planation surface, eroded across the crystalline basement (plutonic and metamorphic rocks), eruptive rocks of the Gondwana cycle (Early to Middle Carboniferous), and Jurassic volcanic rocks.The most important active climate during the genesis of this surface had a very significant role, developing intense chemical weathering extending to variable depths with the corresponding degradation of the rocky material exposed at the surface. Remnants of the weathering profiles, both outcropping and fossilized by burial, are identified and described. Such a particular mega-landform was developed in a cratonic environment, mainly as a product of deep weathering, and it is interpreted as a denuded surface, an etchplain formed by corrosion followed by erosion.The analysis of the relationships between relief, saprolite, and rock cover throughout time suggests that the most important factor for the classification of the present landscape is the duration of exposure of the crystalline basement at the surface, from the end of the Paleozoic and during the entire Mesozoic. This conclusion has essential relevance for the evaluation of the effects of Mesozoic tectonics and the powerful weathering under certain climatic conditions. 423 424 E.Y. Aguilera et al.It is estimated that this paleosurface would have initiated its development towards the end of the Paleozoic, but later modifying also the Jurassic volcanic rocks that preceded the rifting processes that lead to the opening of the Southern Atlantic Ocean. Finally, the tectonic activity during the early Tertiary produced the exhumation of the planation surface, which was buried by its own regolith, reactivating erosion surfaces and small drainage basins. However, it is possible that some areas of the planation surface had never been covered by other rocks, other than its own overlying weathering products.Our results suggest that the landscape features should not be assigned to Quaternary morphogenesis, but instead, they have evolved over a very long time, perhaps 100 Ma or even more. These observations refer to Mesozoic times, and therefore the time scale used for the discussion of the geomorphology of the Northern Patagonian Massif should be enlarged to properly analyze the evolution of the ancient landscapes of this cratonic region.This chapter contributes to the analysis of comparative studies of global geomorphology of cratonic areas, where planation surfaces record very long periods in which the speed of crustal deformation is highly compensated by planation processes.

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A General Overview of Gondwana Landscapes in Argentina

Cited by 21 publications

References 24 publications

Exhumation history and landscape evolution of the Sierra de San Luis (Sierras Pampeanas, Argentina) - new insights from low - temperature thermochronological data

Exhumation history and landscape evolution of the Sierra de San Luis (Sierras Pampeanas, Argentina) - new insights from low - temperature thermochronological data

Evidences of Widespread Cretaceous Deep Weathering and Its Consequences: A Review

Paleo-landscapes of the Northern Patagonian Massif, Argentina

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