Deformacion compresiva cuaternaria en la Cordillera Principal de Chile central (Cajon del Maipo, este de Santiago).Quaternary compressional deformation in the Main Cordillera of Central Chile (Cajon del Maipo, east of Santiago).

Lavenu, Alain; Cembrano, José

doi:10.5027/andgeov35n2-a03

Cited by 2 publications

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“…3A). Neotectonic activity of arc-oblique structures within the study area has been demonstrated by Lavenu and Cembrano (2008). They showed that Quaternary terraces of the Maipo river have been faulted and folded by NE and WNW-striking reverse faults, parallel to the trend of regional-scale faults recognized by this study (Fig.…”

Section: Fault Intersections Damage and Permeabilitysupporting

confidence: 76%

Long-lived crustal damage zones associated with fault intersections in the high Andes of Central Chile

Romo

Yáñez

Rivera

et al. 2019

andgeo

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Long-lived, high-angle fault systems constitute high-permeability zones that can localize the upward flow of hydrothermal fluids and magma throughout the upper crust. Intersections of these types of structures can develop complex interference patterns, which constitute volumes of damaged rock (networks of small-scale faults and fractures) where permeability may be significantly enhanced. This is relevant for understanding regional-scale structural controls on the emplacement of hydrothermal mineral deposits and volcanic centers, and also on the distribution of areas of active upper-crustal seismicity. In the high Andes of central Chile, regional-scale geophysical (magnetic, gravimetric, seismic) and structural datasets demonstrate that the architecture of this Andean segment is defined by NW- and NE-striking fault systems, oblique to the N-S trend of the magmatic arc. Fault systems with the same orientations are well developed in the basement of the Andes. The intersections of conjugate arc-oblique faults constitute the site of emplacement of Neogene intrusive complexes and giant porphyry Cu-Mo deposits, and define the location of major clusters of upper-crustal earthquakes and active volcanic centers, suggesting that these fault systems are still being reactivated under the current stress regime. A proper identification of one-dimensional, lithospheric-scale high-permeability zones located at the intersections of high-angle, arc-transverse fault systems could be the key to understanding problems such as the structural controls on magmatic and hydrothermal activity and the patterns of upper-crustal seismicity in the high Andes and similar orogenic belts

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Section: Fault Intersections Damage and Permeabilitysupporting

confidence: 76%

Long-lived crustal damage zones associated with fault intersections in the high Andes of Central Chile

Romo

Yáñez

Rivera

et al. 2019

andgeo

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“…Focal mechanisms indicate normal movement of the SW-dipping Pichilemu fault (Farías et al, 2011;Aron et al, 2013), consistent with the expected relaxation of NWstriking crustal faults (normally under compression) during the co-and post-seismic periods, as was also observed in the volcanic arc at the Main Cordillera (Spagnotto et al, 2015). In the Main Cordillera, there is no direct evidence of neotectonic activity of the PFS, but similar, WNW-striking faults have been shown to displace Quaternary terraces of the Maipo River, ∼ 25 km to the north of the PFS (Lavenu and Cembrano, 2008). One of the focal mechanism solutions of the Las Melosas earthquake, a major (M w 6.9) intraplate seismic event registered in 1958 in the Main Cordillera, less than 10 km to the north of the PFS, is compatible with activity along a WNW-striking fault (Alvarado et al, 2009).…”

Section: Beyond the Pfs: The Maipo Deformation Zonesupporting

confidence: 71%

“…The strike of individual veins varies from ENE to WNW, but the whole vein system defines a WNW-trending belt, 1.5 km long and 200 m wide. The veins are composed of quartz, calcite and barite with a sulfide ore of galena, sphalerite, tennantite/tetrahedrite, chalcopyrite and bornite (Leal, 2019), and they are syn-tectonic, as demonstrated by several pieces of evidence of hydrothermal mineral crystallization during fault slip (Fig. 4).…”

Section: Structural Settingmentioning

confidence: 99%

The Piuquencillo fault system: a long-lived, Andean-transverse fault system and its relationship with magmatic and hydrothermal activity

Piquer

Rivera²,

Yáñez

et al. 2021

Solid Earth

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Abstract. Lithospheric-scale fault systems control the large-scale permeability in the Earth's crust and lithospheric mantle, and its proper recognition is fundamental to understand the geometry and distribution of mineral deposits, volcanic and plutonic complexes and geothermal systems. However, their manifestations at the current surface can be very subtle, as in many cases they are oriented oblique to the current continental margin and to the axis of the magmatic arc; be partially obliterated by younger, arc-parallel faults; and also be covered by volcanic and sedimentary deposits, through which the fault might propagate vertically. The Piuquencillo fault system (PFS) is a proposed lithospheric-scale fault system, located in the Main Cordillera of central Chile. Here, we present the results of the first detailed field study of the PFS, based on structural data collected at 82 structural stations distributed across all the western Main Cordillera. The first published U–Pb zircon ages for the La Obra batholith, which is bounded to the south by the PFS but also affected by younger reactivations of it, were obtained. They yielded 20.79 ± 0.13 Ma (granodiorite) and 20.69 ± 0.07 Ma (monzogranite). Statistical analysis of fault-plane data shows that the presence of the PFS is reflected on a strong preferred NW to WNW strike, with variable dip directions, evident from the analysis of the total fault-plane population and also from individual segments of the PFS. In some segments, the presence of major NE- to ENE-striking faults which intersect the PFS is also reflected in the preferred orientation of fault planes. Preferred orientations of hydrothermal veins, breccias and dikes show that both the PFS and some ENE-striking faults were capable of channelling hydrothermal fluids and magma. Kinematic and dynamic analysis of fault-plane data reveals that most of the PFS was reactivated with sinistral ± reverse kinematics during the Neogene, under a strike-slip to transpressive regime with E- to ENE-trending shortening direction (σ1). Detailed kinematic and dynamic analyses were completed for various segments of the PFS and also for the different rock units affected by it. This study supports the concept that the PFS is a lithospheric-scale fault system, which strongly controlled deformation and the flow of magmas and hydrothermal fluids during the Neogene. The PFS forms part of a larger, margin-transverse structure, the Maipo deformation zone, a continental-scale discontinuity which cut across the entire Chilean continental margin and has been active at least since the Jurassic.

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Deformacion compresiva cuaternaria en la Cordillera Principal de Chile central (Cajon del Maipo, este de Santiago).Quaternary compressional deformation in the Main Cordillera of Central Chile (Cajon del Maipo, east of Santiago).

Cited by 2 publications

References 0 publications

Long-lived crustal damage zones associated with fault intersections in the high Andes of Central Chile

Long-lived crustal damage zones associated with fault intersections in the high Andes of Central Chile

The Piuquencillo fault system: a long-lived, Andean-transverse fault system and its relationship with magmatic and hydrothermal activity

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