Salar Grande pull-apart basin, Atacama Fault System, northern Chile

Reijs, J.; McClay, Ken

doi:10.1144/gsl.sp.1998.135.01.09

Cited by 15 publications

(11 citation statements)

References 16 publications

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“…12). Other examples of large-scale strike-slip fault systems, with block segmentation through releasing and restraining stepovers, are the San Andreas Fault (Sylvester, 1988), the Echo Hills in Southeastern Nevada (Aydn and Nur, 1985), or the Atacama Fault in northern Chile (Reijs and McClay, 1998). Welldefi ned 'pop-up' structures are rarely described, probably because of the complex geometries of the fault systems and because they are regions of uplift that rapidly become eroded after formation.…”

Section: Discussionmentioning

confidence: 99%

Cooling histories and deformation of plutonic rocks along the Liquiñe-Ofqui Fault Zone, Southern Chile (41°-42°15'S)

Adriasola

Stöckhert

2008

Rev. geol. Chile

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ABSTRACT. Structural and microstructural observations combined with apatite and zircon fi ssion-track thermochronology within two sectors of the Main Andean Range in the Los Lagos Region of Chile reveal an episodic history of intrusion and deformation in the North Patagonian Batholith (NPB). A dextral displacement of ~30 km along the Liquiñe-Ofqui fault zone (LOFZ) is inferred from the correlation of corresponding Cretaceous intrusions of the NPB across the fault zone at Reloncaví. Relative uplift of the western block in the late Miocene is indicated by apatite and zircon fi ssiontrack cooling histories. Microstructures in samples from Miocene and Cretaceous plutons along the fault zone generally indicate deformation at temperatures below ~300°C, with the exception of some samples from Cretaceous intrusions showing deformation at higher temperatures. In the Hornopirén area, signifi cant relative uplift of the eastern block is indicated by 1. the different styles of deformation observed across the fault zone, 2. kinematic analysis of a shear zone in tonalite and 3. geobarometry of contact metamorphic mineral assemblages. For the plutonic rocks in the Hornopirén area, extremely rapid cooling is indicated by thermochronometry, suggesting the activity of hydrothermal systems or thermal effects of late shallow intrusions.

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Section: Discussionmentioning

confidence: 99%

Cooling histories and deformation of plutonic rocks along the Liquiñe-Ofqui Fault Zone, Southern Chile (41°-42°15'S)

Adriasola

Stöckhert

2008

Rev. geol. Chile

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“…Shaded relief map with seismic stations PATCX, PB02, and creepmeter installation CHO2. Contour of Salar Grande is from Reijs and McClay []. The environment of station PATCX is influenced by salt sediment, unlike PB02, which is at a similar distance but upslope from the Salar Grande.…”

Section: Model For Periodic Velocity Changementioning

confidence: 99%

Comprehensive observation and modeling of earthquake and temperature‐related seismic velocity changes in northern Chile with passive image interferometry

et al. 2014

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We report on earthquake and temperature‐related velocity changes in high‐frequency autocorrelations of ambient noise data from seismic stations of the Integrated Plate Boundary Observatory Chile project in northern Chile. Daily autocorrelation functions are analyzed over a period of 5 years with passive image interferometry. A short‐term velocity drop recovering after several days to weeks is observed for the Mw 7.7 Tocopilla earthquake at most stations. At the two stations PB05 and PATCX, we observe a long‐term velocity decrease recovering over the course of around 2 years. While station PB05 is located in the rupture area of the Tocopilla earthquake, this is not the case for station PATCX. Station PATCX is situated in an area influenced by salt sediment in the vicinity of Salar Grande and presents a superior sensitivity to ground acceleration and periodic surface‐induced changes. Due to this high sensitivity, we observe a velocity response of several regional earthquakes at PATCX, and we can show for the first time a linear relationship between the amplitude of velocity drops and peak ground acceleration for data from a single station. This relationship does not hold true when comparing different stations due to the different sensitivity of the station environments. Furthermore, we observe periodic annual velocity changes at PATCX. Analyzing data at a temporal resolution below 1 day, we are able to identify changes with a period of 24 h, too. The characteristics of the seismic velocity with annual and daily periods indicate an atmospheric origin of the velocity changes that we confirm with a model based on thermally induced stress. This comprehensive model explains the lag time dependence of the temperature‐related seismic velocity changes involving the distribution of temperature fluctuations, the relationship between temperature, stress and velocity change, plus autocorrelation sensitivity kernels.

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“…[8] Most deformation of the Precordillera and the forearc is Paleogene and older in age and is related to major subvertical strike-slip fault systems that originally developed as oblique contractional structures in the various magmatic arc segments (Precordilleran fault system [Scheuber and Reutter, 1992;Reutter et al, 1996;Tomlinson [Scheuber and Andriessen, 1990;Reijs and McClay, 1998;Scheuber and Gonzalez, 1999]). They were recently reactivated with transtensional kinematics and some vertical axis block rotations with a clockwise sense [Randall et al, 1996;Kuhn, 2002].…”

Section: Regional Geomorphology and Geologymentioning

confidence: 99%

“…PFS, Precordilleran fault system. and Blanco, 1997]; Atacama fault system [Scheuber and Andriessen, 1990;Reijs and McClay, 1998;Scheuber and Gonzalez, 1999]). They were recently reactivated with transtensional kinematics and some vertical axis block rotations with a clockwise sense [Randall et al, 1996;Kuhn, 2002].…”

Section: Regional Geomorphology and Geologymentioning

confidence: 99%

Uplift of the western Altiplano plateau: Evidence from the Precordillera between 20° and 21°S (northern Chile)

2004

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We present a quantitative reconstruction of uplift of the western flank of the Altiplano plateau (central Andes), one of the largest monoclines on the Earth, on the basis of an analysis of tectonic structures, syntectonic deposits, and geophysical data. Uplift occurred on a west vergent, slowly propagating system of high‐angle reverse faults merging into a joint detachment that ramps down to midcrustal levels below the plateau edge. The upper ramps determine local fold geometries while the lower ramp controls large‐scale surface tilting and uplift. At 20°S, this fault system was active between ∼30 Ma and 5–10 Ma, with maximum shortening rates of 0.22 mm/yr between 17 and 10 Ma. It generated some 2600 m of surface uplift with only minor shortening of ∼3000 m. Its activity was largely synchronous to eruption of large‐volume ignimbrites from a midcrustal source. Geophysical data indicate that the fault system localized deformation at the boundary between a cool, strong forearc crust and a presumably fluid‐rich and/or partially molten zone underneath the plateau area. The systematic relation between crustal melting and shortening with uplift at the western plateau margin can be traced along most of the plateau flank, with a stepwise decrease in age of deformation and magmatism toward the south indicating discontinuous addition of plateau segments. Crustal thickening to as much as 70 km from westward underthrusting in the back arc parts of the plateau isostatically compensated the tectonic surface uplift and monocline formation with respect to a stable forearc, which only reacted with minor tilting.

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Salar Grande pull-apart basin, Atacama Fault System, northern Chile

Abstract: The Salar Grande basin is a 'poly-history' strike-slip basin along the north-trend-

Cited by 15 publications

References 16 publications

Cooling histories and deformation of plutonic rocks along the Liquiñe-Ofqui Fault Zone, Southern Chile (41°-42°15'S)

Cooling histories and deformation of plutonic rocks along the Liquiñe-Ofqui Fault Zone, Southern Chile (41°-42°15'S)

Comprehensive observation and modeling of earthquake and temperature‐related seismic velocity changes in northern Chile with passive image interferometry

Uplift of the western Altiplano plateau: Evidence from the Precordillera between 20° and 21°S (northern Chile)

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