Geomorphological west-east-section through the north chilean andes near antofagasta

Abele, Gerhard

doi:10.1007/bfb0045180

Cited by 4 publications

(3 citation statements)

References 11 publications

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“…The Longitudinal Valley and the Chilean Precordillera are part of one westward-tilted crustal block with erosion at the uplifted Precordillera side and deposition of the eroded material on the subsided Longitudinal Valley side. Since the Coastal Cordillera is uplifted faster than the downward incision of its valleys advances, it operates as a dam preventing sediment transport from the Longitudinal Valley to the coast (Abele 1988).…”

Section: Discussionmentioning

confidence: 99%

“…There is evidence that at depths of 30 -60 km within the underthrusting Nazca plate, maximum compressive stress and plate motion correspond in the azimuth of N 85° E and in the dip of 20° E. Focal Seismic activity (Wigger 1988), recent plutonism (Schwarz et al 1986) and volcanism, neotectonics such as thrusting and folding (Schwab 1985, Reutter et al 1988, actual normal and wrench faulting (Okada 1971, Salfity 1985, Scheuber et al 1986, Strecker et al 1989, current uplift of marine terraces (Ratusny & Radtke 1988) and present basin subsidence (Abele 1988) all establish the contemporaneous building of the Andes. An assumed in situ stress field with an E-W directed maximum horizontal compressive stress component deriving from the E-W convergence at the western active margin of the South American plate and from the E-W divergence at its eastern passive margin, would not explain the N-S alignment of alternating uplifted and subsided crustal segments that dominate the Andean morphology.…”

Section: Introductionmentioning

confidence: 97%

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State of In Situ Stress in Northern Chile and in Northwestern Argentina

Schäfer

Dannapfel

1994

Tectonics of the Southern Central Andes

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Section: Discussionmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 97%

State of In Situ Stress in Northern Chile and in Northwestern Argentina

Schäfer

Dannapfel

1994

Tectonics of the Southern Central Andes

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“…These sedimentary rocks locally show strong westward stratification (Figure 7) which results from additional rotation of the initially west dipping strata in the hanging wall of the thrusts. The beds are cut by an angular unconformity which is correlated with a regional middle Miocene interval of pedimentation [ Abele , 1988; Naranjo et al , 1994]. The unconformity is overlain by the Tucucaro Ignimbrite which yielded a 40 K/ 40 Ar age of 3.2 ± 0.3 Ma [ Ramírez and Gardeweg , 1982].…”

Section: Interpretation and Timing Constraintsmentioning

confidence: 99%

Fold and thrust belt structures and strike‐slip faulting at the SE margin of the Salar de Atacama basin, Chilean Andes

Kuhn¹

2002

Tectonics

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A tectonic reinterpretation is reported for the southeastern margin of the Salar de Atacama basin of northern Chile. Detailed structural mapping revealed the presence of an east vergent thin‐skinned fold and thrust belt affecting Oligocene‐Miocene Paciencia Group rocks and the overlying Plio‐Pleistocene volcanic rocks. Along‐strike segmentation of the main fold implies local foreland influence on footwall ramp geometry leading to local thrust sheet rotation. To the east the adjacent western slope of the Western Cordillera displays two different structural domains, probably controlled by preexisting basement structures. The southern domain comprises two N‐S oriented sigmoidal belts of linear arranged pressure ridges, indicating left‐lateral transpression. In contrast, the northern domain is characterized by east vergent fold and thrust belt structures and reactivated NW‐SE striking sinistral strike‐slip faults, governing clockwise block rotations. An indenter‐driven deformation model is proposed to explain sinistral transpression and clockwise block rotations around vertical axes. This variant of a small‐block rotation mechanism is discussed in the context of oroclinal bending of the central Andes, emphasizing the significance of ancient structures in controlling rotations.

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Arid and Semi-Arid Ecosystems

Rundel¹,

Villagra²

2007

The Physical Geography of South America

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Arid and semi-arid ecosystems in South America are best illustrated by two desert regions, the Peruvian and Atacama Deserts of the Pacific coast and the Monte Desert of central Argentina. The caatinga of northeast Brazil is often described as semi-arid, but mostly receives 500–750 mm of annual rainfall and is better regarded as dry savanna. Small areas of Venezuela and Colombia near the Caribbean coast, and nearby offshore islands, support desert-like vegetation with arborescent cacti, Prosopis, and Capparis, but generally receive up to 500 mm annual rainfall. Substrate conditions, as much or more than climate, determine the desert-like structure and composition of these communities, and thus they are not discussed further here. Extensive areas of Patagonian steppe also have semi-arid conditions, as discussed in chapter 14. The Peruvian and Atacama Deserts form a continuous belt along the west coast of South America, extending 3,500 km from near the northern border of Perú (5°S) to north-central Chile near La Serena (29°55’S), where the Mediterranean- type climate regime becomes dominant. The eastward extent of the Peruvian and Atacama Deserts is strongly truncated where either the coastal ranges or Andean Cordillera rise steeply from the Pacific coast and, as a biogeographic unit, the desert zone may extend from 20 to 100 km or more inland. A calculation of the area covered by these deserts depends in part on how this eastern margin is defined. Thus the Peruvian Desert covers between 80,000 and 144,000 km2, while the Atacama Desert of Chile extends over about 128,000 km2 if the barren lower slopes of the Andes are included. Actual vegetated landscapes are far smaller and for the lomas of Perú change dramatically between years depending on rainfall. Only about 12,000 km2 of the Atacama contain perennial plant communities, largely in the southern portion known as the Norte Chico but also including a narrow coastal belt of lomas extending northward almost to Antofagasta and the Prosopis woodlands of the Pampa del Tamarugal. The vegetated areas of the coastal lomas of Perú and Chile together probably do not exceed 4,000 km2 as a maximum following El Niño rains.

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Geomorphological west-east-section through the north chilean andes near antofagasta

Cited by 4 publications

References 11 publications

State of In Situ Stress in Northern Chile and in Northwestern Argentina

State of In Situ Stress in Northern Chile and in Northwestern Argentina

Fold and thrust belt structures and strike‐slip faulting at the SE margin of the Salar de Atacama basin, Chilean Andes

Arid and Semi-Arid Ecosystems

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