Tectonic Evolution of the Central Andes: From Terrane Accretion to Crustal Delamination

Ramos, Víctor A.

doi:10.1306/13622115m1172855

Cited by 10 publications

(10 citation statements)

References 112 publications

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“…Looking at the bulk of inherited grains, only one is Archean, and only three others are Paleoproterozoic. Possible sources for them must be attributed to basement rocks that, in this case, may belong to some parts of the Arequipa Massif, which forms the crustal basement right below the main extensional zone of the Eastern Cordillera (Loewy et al 2004, Ramos 2018a. Several inherited grains indicated Mesoproterozoic ages, for which the possible sources could be located in the Western part of the Amazonian Craton (Cordani et al 2000), but only a few of them are clearly related to the Grenvillian Orogeny that is widespread all along the basement of the Andean Chain (Ramos & Alemán 2000).…”

Section: Discussionmentioning

confidence: 99%

“…They correspond to Ordovician metapelites of the Amutara and Coroico formations and to Silurian siltstones, slates, glacimarine deposits and sandstones of the Cancañiri, Catavi, Uncia and Llallagua formations. Following the review made by Ramos (2018a) on the tectonic evolution of the Central Andes, the Phanerozoic tectonic history of the Cordillera Real could be briefly resumed as follows:…”

Section: Geological Backgroundmentioning

confidence: 99%

“…These granitic plutons are controlled by the localized extension along the hanging-wall of previous sutures; • The Cenozoic Andean evolution was dominated by a shallowing wave of the subducted slab. The consequent migration of magmatism to the foreland induced the formation of an "inner arc", in which deep crustal melts were formed following crustal delamination and lithospheric mantle removal (Ramos 2018a). The Oligocenic upper crustal granitoids (IIlimani, Quimsa Cruz and Santa Vera Cruz plutons) related to compressional tectonics associated with the subduction slab steepening ( Jiménez & López-Velásquez 2008) were dated by Gillis et al (2006).…”

Section: Geological Backgroundmentioning

confidence: 99%

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Geochronological systematics of the Huayna Potosí, Zongo and Taquesi plutons, Cordillera Real of Bolivia, by the K/Ar, Rb/Sr and U/Pb methods

2019

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The Huayna Potosi, Zongo and Taquesi are Triassic plutons located at the core of the Real Cordillera of Bolivia. In this paper, several Rb-Sr and K-Ar ages obtained in the past at the São Paulo Geochronology Laboratory, yet unpublished, will be presented, along with newer U-Pb Sensitive High-Resolution Ion Microprobe (SHRIMP) determinations made in the same laboratory, allowing us to redefine the geologic history of this part of the Central Andes. Rb/Sr analyses of some low grade metapelitic country rocks of the early Paleozoic (Amutara and Cancañiri Formations) yielded a Rb-Sr isochron age of 344 ± 38 Ma, indicating the action of an early Gondwanide regional event. A five-point Rb-Sr isochron from a granite outcrop of the Huayna Potosi pluton yielded an age of 224 ± 28 Ma. In addition, an important Ar loss in micas was detected in the Zongo granitoids and their country rocks, recording a thermal event that opened this isotopic system in the Oligocene. Newer U-Pb SHRIMP zircon ages of ca. 221 Ma were obtained in two other granitic outcrops of the Huayna Potosi granite. They confirmed its Triassic crystallization age, and a similar U-Pb SHRIMP age of 221.9 ± 1.5 Ma was obtained for one sample of the Taquesi pluton. For the Zongo pluton, many of the zircon grains obtained from one sample of its Kuticucho facies yielded extremely high uranium content, which produced reverse discordant apparent ages. However, due to the fair alignment of the analytical points in the Concordia diagram, possibly corresponding to a linear correlation, we made a regression calculation and the interception of the Concordia curve resulted in a rather imprecise age of 220 ± 20 Ma. Our conclusion was that the final magmatic crystallization and the intrusion of plutons in the central part of the Cordillera Real of Bolivia have occurred close to 221.5 ± 2.0 Ma, in late Triassic times. Finally, the U-Pb SHRIMP ages obtained in inherited zircon xenocrysts from the four available granitic rocks yielded very different ages, and many of them are related to previous magmatic episodes of the Andean Tectonic System. A few other age measurements indicated sources related to much older Proterozoic magmatic events associated with rocks from the Andean basement.

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Section: Discussionmentioning

confidence: 99%

Section: Geological Backgroundmentioning

confidence: 99%

Section: Geological Backgroundmentioning

confidence: 99%

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Geochronological systematics of the Huayna Potosí, Zongo and Taquesi plutons, Cordillera Real of Bolivia, by the K/Ar, Rb/Sr and U/Pb methods

2019

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“…Retro-arc pelites to metapelites associated with the Famatinian magmatic arc of late Neoproterozoic to middle and late Devonian age are represented in the study area as Ordovician, Silurian and Devonian formations (Ramos, 2018).…”

Section: Regional Framework and Geological Historymentioning

confidence: 99%

“…This rift was widespread along the western border of the South American continent. The two Oligocene plutons were emplaced in a compressional regime, apparently related to subduction, coeval with uplifting of large plateaux (Altiplano and Puna), delamination of the lower crust and widespread mafic flows (Jiménez and López-Velásquez, 2008;Ramos, 2018). The country rocks for these anatectic granitoids are lower Paleozoic metapelites.…”

Section: Introductionmentioning

confidence: 99%

Geochronology of the Cordillera Real granitoids, the inner magmatic arc of Bolivia

Iriarte

Cordani

Sato

2021

andgeo

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The Real Cordillera granitoids are a suite of Triassic and Oligocene plutons located at the core of the Eastern Cordillera of the Central Andes of Bolivia. Its geotectonical setting, chemical and ore composition make them part of the so called “Inner Magmatic Arc” which differs from the actual “Magmatic Arc” located immediately to the west. U-Pb SHRIMP ages were obtained in order to constrain their crystallization ages. The Triassic group yielded the following results: 240 ± 2 Ma for the Huato granite, 230.7 ± 1.3 Ma for the Illampu granodiorite, 222.2 ± 2.4 Ma for the Huayna Potosí granite and 221.9 ± 1.5 Ma for the Taquesi granodiorite. For the Oligocene group we obtained two ages of 26.87 ± 0.26 and 26.88 ± 0.21 Ma both for the Quimsa Cruz granite. Mafic enclaves from the Illampu and Taquesi granodiorites report ages that were older than their respective granitoid hosts, yielding 234.1 ± 1.3 Ma and 227 ± 1.3 Ma, respectively. Secondary processes related to regional thermal anomalies and magmatic melt-enrichment, reset the K/Ar and U/Pb isotopic systems, producing: a) younger ages by Ar loss and b) older ages by U/Pb isotopic ratios reorganization. As noted in previous studies, the Zongo/Kuticucho Triassic granite yielded extremely high U enrichment in most zircon analysed, producing reset of U/Pb ratios, wide span in age ranges and reverse discordia curves that obscure its actual crystallization age. Relatively abundant zircon inheritance was found in these “cold” and inheritance-rich granitoids, with ages suggesting provenance from early Paleozoic metapelites that also recycled older sources. This relatively abundant xenocrystic inheritance records the influence of the Gondwanide orogeny (336-205 Ma) as an overall subduction arc environment, punctuated at its final stage with the imprint of a continental rifting (245-220 Ma).

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Tectonic controls on late Cambrian-Early Ordovician deposition in Cordillera oriental (Northwest Argentina)

Vaucher

Vaccari

Balseiro

et al. 2020

Int J Earth Sci (Geol Rundsch)

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Tectonic Evolution of the Central Andes: From Terrane Accretion to Crustal Delamination

Cited by 10 publications

References 112 publications

Geochronological systematics of the Huayna Potosí, Zongo and Taquesi plutons, Cordillera Real of Bolivia, by the K/Ar, Rb/Sr and U/Pb methods

Geochronological systematics of the Huayna Potosí, Zongo and Taquesi plutons, Cordillera Real of Bolivia, by the K/Ar, Rb/Sr and U/Pb methods

Geochronology of the Cordillera Real granitoids, the inner magmatic arc of Bolivia

Tectonic controls on late Cambrian-Early Ordovician deposition in Cordillera oriental (Northwest Argentina)

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