Holocene shortening rates of an Andean-front thrust, Southern Precordillera, Argentina

Costa, Carlos H.; Ahumada, Emilio A.; Vazquez, Fabricio Rodrigo; Kröhling, Daniela

doi:10.1016/j.tecto.2015.09.017

Cited by 17 publications

(12 citation statements)

References 40 publications

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“…Shortening rate discrepancies may also account for temporal variations suggesting an acceleration of the thrust activity during the Holocene. Another explanation is that youngest activity of the Las Peñas thrust is concentrated at the northern and/or southern ends of the thrust system, as suggested for the Las Higueras thrust by Schmidt, Hetzel, Mingorance, and Ramos () and Costa et al (). Thus, the lack of a single thrust plane coupled with different kinematic evolutionary paths may lead to a complicated, mosaicked deformation pattern, with variations in activity rate both along the thrust trace and on individual splays.…”

Section: Discussionmentioning

confidence: 92%

“…Spatial variation in shortening rates along the Las Peñas thrust can be envisaged as internal kinematic heterogeneities, with local shortening rates only representative for individual splays. Variation in shortening rates may also be due to interaction with other regional faults, considering that other structures also contribute to the regional shortening in this complex area (Ahumada & Costa, ; Costa et al, ; Kendrick et al, , ; Ramos et al, ). The study site is located within a zone where two major thrust systems with opposite vergence merge, the Las Peñas and the Montecito‐Cerro Salinas thrusts (Bohon, ; Costa et al, ; Vergés et al, ).…”

Section: Discussionmentioning

confidence: 99%

“…The Las Higueras thrust carries Paleozoic and Triassic rocks over Triassic and Cenozoic sedimentary strata. Evidence of Quaternary activity has been documented at both the northern and southern ends of the range (Ahumada & Costa, ; Costa et al, ; Salomon et al, ; Schmidt, Hetzel, Mingorance, et al, ). The Las Peñas thrust is the main mountain‐piedmont bounding structure to the east, carrying Neogene clastic rocks over thick Pleistocene alluvial fan deposits (Ahumada & Costa, ; Cortés & Costa, ; Costa et al, ; Costa, Diederix, et al, ; Figueroa & Ferraris, ; Schmidt, Hetzel, Mingorance, & Ramos, ).…”

Section: Geologic Settingmentioning

confidence: 99%

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Assessing Quaternary Shortening Rates at an Andean Frontal Thrust (32°30′S), Argentina

et al. 2019

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At the latitude of 32–33°S, the orogenic front of the eastern flank of the Andes is located in the Southern Precordillera, where two major thrusts concentrate Quaternary deformation at the surface. We estimate the shortening rate for one of these, the Las Peñas thrust, for the last ~200 ka, at the site of one of the best exposures of Quaternary thrusting along the Andes. Shortening was estimated across two prominent splays of the deformation zone at the mouth of the Las Peñas River through balanced cross‐sections by using a terrace surface as a marker of cumulative deformation. Terrace ages were constrained through cosmogenic isotopes (10Be) analysis on quartz cobbles collected from the surface and three depth profiles. Results indicate a mean shortening rate across the Las Peñas thrust of 0.27 + 0.11 mm/a. Our results are lower than Holocene shortening rates (1.9–2.4 mm/a) obtained for individual splays of the Las Peñas thrust nearby. We discuss these discrepancies and implications for thrust evolution since the Late Pleistocene, in particular regarding along‐strike rate variations that highlight the complexity of the Quaternary‐active thrust deformation zone. We argue that ongoing stream incision rates largely prevail with respect to thrust activity at the study site. This observation might be connected with a recent (Holocene?) basinward shift of blind thrust activity.

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Section: Discussionmentioning

confidence: 92%

Section: Discussionmentioning

confidence: 99%

Section: Geologic Settingmentioning

confidence: 99%

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Assessing Quaternary Shortening Rates at an Andean Frontal Thrust (32°30′S), Argentina

et al. 2019

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“…For instance, interpretation of GPS‐derived slip rates across individual structures is currently impossible due to the sparseness of GPS stations. Further, the activity of most of the structures in the Precordillera and the Sierras Pampeanas have not been quantified since there is still a paucity of studies employing geochronological techniques to determine slip rates (Costa, Ahumada, Vázquez, et al, , and references therein).…”

Section: Introductionmentioning

confidence: 99%

“…The 30‐m ASTER digital elevation model showing tectonic features (Costa et al, ; Siame et al, ), seismicity (Engdahl & Villaseñor, ), GPS velocity field (Brooks et al, ), and Quaternary slip rate data (Costa, Ahumada, Vázquez, & Kröhling, ; Costa, Ahumada, Gardini, et al, ; Costa et al, ; Rockwell et al, ; Salomon et al, ; Schmidt et al, ; Schoenbohm et al, ; Siame et al, , , ) in the Pampean flat slab segment. The red box shows the location of Figure .…”

Section: Introductionmentioning

confidence: 99%

Late Quaternary Activity of the La Rinconada Fault Zone, San Juan, Argentina

et al. 2019

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Most of the permanent deformation in the Pampean Flat slab segment of the central Andes is taken up at the Andean Orogenic Front in Argentina, a narrow zone between the Eastern Precordillera and Sierras Pampeanas that comprises one of the world's most seismically active thrust zones. Active faults and folds in the region have been extensively mapped but still largely lack information on style and rates of deformation, which is essential for understanding the distribution of regional strain and estimating the seismic potential of individual faults. Structural, geomorphic, and 36 Cl cosmogenic radionuclide surface exposure age methods are used to focus on key sites along the 30-km-long La Rinconada Fault Zone in this region of west-central Argentina, which is~15 km away from the highly populated (~500,000) city of San Juan, to define a late Quaternary average shortening rate of 0.41 ± 0.01 mm/year. This slip rate is the same order of magnitude, but slightly lower than nearby similar east dipping Eastern Precordillera faults including the La Laja and Las Tapias Faults. Relatively low slip rates are interpreted as being a consequence of distributed deformation between the latitude of the La Rinconada Fault Zone (31 and 32°S), as compared to between latitudes 32 to 33°S where deformation appears to be focused on fewer structures, including the Las Peñas and La Cal Thrust Faults. The La Rinconada Fault Zone is capable of generating earthquakes of M w 6.6-7.2, but further investigations are required to determine timing and recurrence intervals of discrete events.

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Linking earthquake-triggered paleolandslides to their seismic source and to the possible seismic event that originated them in a portion of the Argentine Precordillera (31°–33°S)

et al. 2021

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Holocene shortening rates of an Andean-front thrust, Southern Precordillera, Argentina

Cited by 17 publications

References 40 publications

Assessing Quaternary Shortening Rates at an Andean Frontal Thrust (32°30′S), Argentina

Assessing Quaternary Shortening Rates at an Andean Frontal Thrust (32°30′S), Argentina

Late Quaternary Activity of the La Rinconada Fault Zone, San Juan, Argentina

Linking earthquake-triggered paleolandslides to their seismic source and to the possible seismic event that originated them in a portion of the Argentine Precordillera (31°–33°S)

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