Active faulting in northern Chile: ramp stacking and lateral decoupling along a subduction plate boundary?

Armijo, Rolando; Thiele, Ricardo

doi:10.1016/0012-821x(90)90087-e

Cited by 146 publications

(133 citation statements)

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“…Along with the GPS sites, Figure 1 depicts a morphological sketch map of the area under investigation. The Coastal Cordillera, as part of the fore-arc, has been attributed to extension and gravitational collapse by different authors (ARMIJO and THIELE, 1990;. This is in contrast to most parts of the Central Andes which are known to show dominantly E -W shortening (ISACKS, 1988;GUBBELS et al, 1993;SCHMITZ, 1994;WHITMAN et al, 1996;OKAYA et al, 1997;ALLMENDINGER et al, 1997;NORABUENA et al, 1998).…”

Section: Study Areamentioning

confidence: 39%

“…This is in contrast to most parts of the Central Andes which are known to show dominantly E -W shortening (ISACKS, 1988;GUBBELS et al, 1993;SCHMITZ, 1994;WHITMAN et al, 1996;OKAYA et al, 1997;ALLMENDINGER et al, 1997;NORABUENA et al, 1998). Major faults or fault zones that originally may have acted as transcurrent faults, such as the Atacama Fault System, currently act either as normal faults (ARABASZ, 1971;OKADA, 1971;NARANJO, 1987) or as strike-slip faults (ARMIJO and THIELE, 1990). The sense of motion on these faults is still a point of controversy.…”

Section: Study Areamentioning

confidence: 93%

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GPS-derived Deformation of the Central Andes Including the 1995 Antofagasta M w = 8.0 Earthquake

Klotz

Angermann

Michel

et al. 1999

Pure and Applied Geophysics

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In order to study both the interplate seismic loading cycle and the distribution of intraplate deformation of the Andes, a 215 site GPS network covering Chile and the western part of Argentina was selected, monumented and observed in 1993 and 1994. A dense part of the network in northern Chile and northwest Argentina, comprising some 70 sites, was re-observed after two years in October/November, 1995. The M w = 8.0 Antofagasta (North Chile) earthquake of 30th July, 1995 took place between the two observations. The city of Antofagasta shifted 80 cm westwards by this event and the displacement still reached 10 cm at locations 300 km from the trench. Three different deformation processes have been considered for modeling the measured displacements: (1) interseismic accumulation of elastic strain due to subduction coupling, (2) coseismic strain release during the Antofagasta earthquake and (3) crustal shortening in the Sub-Andes.Eastward displacement of the sites to the north and to the south of the area affected by the earthquake is due to the interseismic accumulation of elastic deformation. Assuming a uniform slip model of interseismic coupling, the observed displacements at the coast require a fully locked subduction interface and a depth of seismic coupling of 50 km. The geodetically derived fault plane parameters of the Antofagasta earthquake are consistent with results derived from wave-form modeling of seismological data. The coseismic slip predicted by the variable slip model reaches values of 3.2 m in the dip-slip and 1.4 m in the strike-slip directions. The derived rake is 66°. Our geodetic results suggest that the oblique Nazca-South American plate convergence is accommodated by oblique earthquake slip with no slip partitioning. The observed displacements in the back-arc indicate a present-day crustal shortening rate of 3-4 mm/year which is significantly slower than the average of 10 mm/year experienced during the evolution of the Andean plateau.

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Section: Study Areamentioning

confidence: 39%

Section: Study Areamentioning

confidence: 93%

GPS-derived Deformation of the Central Andes Including the 1995 Antofagasta M w = 8.0 Earthquake

Klotz

Angermann

Michel

et al. 1999

Pure and Applied Geophysics

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“…The movement of this fault system was mainly vertical during the Cenozoic (Armijo and Thiele, 1990;Scheuber and Andriessen, 1990;Riquelme et al, 2003).…”

Section: Geological Settingmentioning

confidence: 99%

Origen de las aguas de pequeños manantiales de la costa del norte de Chile, en las cercanías de Antofagasta.

Herrera

Custódio

2014

Andgeo

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ABSTRACT. The origin of waters from small springs located at the hyper-arid northern coast of Chile, in the vicinity of Antofagasta, is discussed after hydrogeochemical and isotopic studies and supported by groundwater flow hydrodynamic considerations. Spring water is brackish to saline, with electrical conductivity ranging from 2 to 25 mS/cm. Chemical and water isotope data ( 18 O and 2 H) show that the rainfall events that produced part of the recharge could correspond to wetter conditions than at present. Their origin could be related to the emplacement of warm sea currents facing the coast of northern Chile, possibly associated to incursions of El Niño Southern Oscillation (ENSO). Radiocarbon dating and preliminary groundwater hydraulic calculations indicate that these spring waters could be remnants of a more significant recharge in the Cordillera de la Costa than that produced today during the less arid period about 5,000 to 3,000 years ago. The exception is Las Vertientes spring which is the only one that receives water transferred from the Central Depression. The springs are the visible discharge of a regional groundwater body in the very low permeability Cordillera de la Costa, whose hydraulic conductivity decreases downward and flow is dominantly though fissures and storage in the low porosity rock matrix. Costa, Antofagasta, Spring, Groundwater, Stable isotopes, Radiocarbon, Arid climate, Recharge. RESUMEN. Origen de las aguas de pequeños manantiales de la costa del norte de Chile, en las cercanías de Antofagasta. Se discute el origen de las aguas que surgen en pequeños manantiales localizados en la costa hiperárida del norte de Chile a partir de un estudio hidrogeoquímico e isotópico, apoyado en consideraciones hidrodinámicas del flujo del agua subterránea. Las aguas de los manantiales son salobres a salinas, con valores de la conductividad eléctrica que varían entre 2 y 25 mS/cm. El estudio de la composición química e isotópica ( 18 O y 2 H) de las aguas revela que las precipitaciones que produjeron la recarga se registraron en condiciones más húmedas que en la actualidad. Su origen estaría relacionado con el emplazamiento de corrientes marinas cálidas frente a las costas del norte de Chile, posiblemente asociadas a la incursión de El Niño-Oscilación del Sur (ENOS). Las dataciones con radiocarbono y los cálculos hidráulicos preliminares indican que las aguas que afloran en estos manantiales pueden corresponder a remanentes de una recarga más significativa ocurrida en un período menos árido que el actual alrededor de 5.000 a 3.000 años atrás, si bien también hay evidencia de alguna recarga reciente en situaciones locales. La única excepción corresponde a las aguas del manantial de Las Vertientes, que recibe contribución de aguas subterráneas de la depresión Central. Los manantiales son la descarga visible de un cuerpo general de agua subterránea en los materiales muy poco permeables de la Cordillera de la Costa, cuya conductividad hidráulica decrece en profundidad y donde el flujo se produce domin...

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“…The Early Cretaceous magmatic arc is represented mostly by quartz diorites to quartz monzodiorites of I-type plutonic rocks, mainly dated between 140 and 120 Ma (Berg et al, 1983;Brook et al, 1987;Pankhurst et al, 1988). Within the Early Cretaceous magmatic arc the most important tectonic feature is the Atacama Fault System, which consists of north-south trending sinistral strike-slip structures (Armijo and Thiele, 1990;Brown et al, 1991). The main faulting occurred between 130 and 126 Ma, and was contemporaneous with the arc magmatism (Scheuber and Andriessen, 1990;Brown et al, 1991).…”

Section: Geological Settingmentioning

confidence: 99%

Geological development and mineralization in the Atacama segment of the South American Andes, northern Chile (26�15??27�25?S)

et al. 1993

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Between the Late Jurassic and the Middle Miocene, widespread magmatism, tectonic events and hydrothermal mineralization characterized the geological evolution of the Atacama segment of the South American Andes. A characteristic feature of this zone is the coincidence in time and space between subduction-generated igneous activity, crustal deformation and mineralization in the magmatic arcs, which formed longitudinal belts migrating eastward.Mineralization in the last 140 Ma is generally restricted to four longitudinal metallogenic belts, in which hydrothermal activity was channelled along crustal-scale faults:(1) the Atacama Fault System, along which Early Cretaceous Cu-Au-bearing breccia pipes, veins and stockwork were formed; (2) the Inca do Oro Belt, which contains Upper Cretaceous low sulphur precious metal epithermal mineralization, and Middle Eocene Cu-Mo -Au-bearing breccia pipes; (3) the West Fissure System, which hosts Upper Eocene to Early Oligocene porphyry copper deposits and high sulphur precious metal epithermal mineralization; and (4) the Maricunga Belt, when contains Upper Oligocene to Middle Miocene high sulphur precious metal epithermal deposits and Au-rich porphyry mineralization.

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Active faulting in northern Chile: ramp stacking and lateral decoupling along a subduction plate boundary?

Cited by 146 publications

References 12 publications

GPS-derived Deformation of the Central Andes Including the 1995 Antofagasta M w = 8.0 Earthquake

GPS-derived Deformation of the Central Andes Including the 1995 Antofagasta M w = 8.0 Earthquake

Origen de las aguas de pequeños manantiales de la costa del norte de Chile, en las cercanías de Antofagasta.

Geological development and mineralization in the Atacama segment of the South American Andes, northern Chile (26�15??27�25?S)

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