U-Pb zircon geochronology of Neoproterozoic–Paleozoic sandstones and Paleozoic plutonic rocks in the Central Andes (21°S–26°S)

Einhorn, J.; Gehrels, George E.; Vernon, Antoine; DeCelles, Peter G.

doi:10.1130/2015.1212(06)

Cited by 8 publications

(16 citation statements)

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“…Early Paleozoic (500-400 Ma) magmatism yields eHf t values that remain intermediate or become slightly more positive in the CA and SA. This positive deviation from average crustal evolution suggests that the widespread early Paleozoic magmatism along the Andean margin (e.g., Rapela et al, 1992;Bahlburg and Hervé, 1997;Pankhurst et al, 1998;Coira et al, 1999;Ducea et al, 2010;Einhorn et al, 2015) may have occurred in an overall extensional tectonic regime with thinned continental crust and significant additions of mantle-derived melt (e.g., Ducea et al, 2015).…”

Section: Crustal Evolutionmentioning

confidence: 99%

Magmatic history and crustal genesis of western South America: Constraints from U-Pb ages and Hf isotopes of detrital zircons in modern rivers

et al. 2016

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Western South America provides an outstanding laboratory for studies of magmatism and crustal evolution because it contains Archean-Paleo protero zoic cratons that amalgamated during Neoproterozoic supercontinent assem bly, as well as a long history of Andean magmatism that records crustal growth and reworking in an accretionary orogen. We have attempted to reconstruct the growth and evolution of western South America through UPb geochrono logic and Hf isotopic analyses of detrital zircons from 59 samples of sand mainly from modern rivers. Results from 5524 new UPb ages and 1199 new Hf isotope determinations are reported. Our data are integrated with previously published geochronologic and Hf isotopic information, yielding a combined record that includes >42,000 ages and >1900 Hf isotope analyses. These large data sets yield five main conclusions: (1) South America has an age distribu tion that is similar to most other continents, presumably reflecting processes of crustal generation and/or preservation related to the supercontinent cycle, with age maxima at 2.2-1.

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Section: Crustal Evolutionmentioning

confidence: 99%

Magmatic history and crustal genesis of western South America: Constraints from U-Pb ages and Hf isotopes of detrital zircons in modern rivers

et al. 2016

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“…The succession discussed here contains detritus from a major Pre-Pampean igneous event (or several events) during the Ediacaran, similar to observations from other successions in the region, such as: the Puncoviscana Complex ; Cambrian rocks of the overlying Méson Group (Augustsson et al, 2011); Neoproterozoic and Paleozoic rocks in Peru (Chew et al, 2008); Devonian rocks in the Central Andes (Bahlburg et al, 2009); Paleozoic rocks in the Central Andes (Augustsson et al, 2015;Einhorn et al, 2015); and Silurian successions in Bolivia (Zimmermann et al, 2015b). In the entire region, however, PrePampean Ediacaran source rocks have not yet been found in outcrop.…”

Section: Implications For the Geodynamic Evolutionmentioning

confidence: 84%

“…This possibility was also considered by Adams et al (2010). Sedimentary successions overlying the Puncoviscana complex (Zimmermann, 2005) do contain this Pampean detrital information but not as a major component (e.g., references in Zimmermann et al, 2014;Augustsson et al, 2011Augustsson et al, , 2015Einhorn et al, 2015;Rapela et al, 2016).…”

Section: Implications For the Geodynamic Evolutionmentioning

confidence: 98%

Pre-Pampean metasedimentary rocks from the Argentinian Puna: Evidence for the Ediacaran margin of Gondwana or the Arequipa–Antofalla–Western Pampeanas block

Naidoo

Zimmermann

Vervoort

2016

Precambrian Research

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“…14A), because ages >1.74 Ga are absent and it lacks late Neoproterozoic, including Brasiliano, ages in general and Pampean ages (650-530 Ma) in particular Escayola et al, 2007Escayola et al, , 2011. It also lacks Famatinian ages ranging between 520 and 450-420 Ma (e.g., Bahlburg et al, 2009;Einhorn et al, 2015). Both Famatinian age groups are typical of Gondwana and very common in a large variety of late Neoproterozoic and Paleozoic sedimentary formations in the central Andes (e.g., Chew et al, 2007bChew et al, , 2008Bahlburg et al, 2009;Cardona et al, 2009;Augustsson et al, 2015;Einhorn et al, 2015;Naidoo et al, 2016;Pepper et al, 2016), but are notably absent from the Chilla beds (Fig.…”

Section: Maximum Depositional Age and Stratigraphic Agementioning

confidence: 99%

The missing link of Rodinia breakup in western South America: A petrographical, geochemical, and zircon Pb-Hf isotope study of the volcanosedimentary Chilla beds (Altiplano, Bolivia)

et al. 2020

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The assembly of Rodinia involved the collision of eastern Laurentia with southwestern Amazonia at ca. 1 Ga. The tectonostratigraphic record of the central Andes records a gap of ∼300 m.y. between 1000 Ma and 700 Ma, i.e., from the beginning of the Neoproterozoic Era to the youngest part of the Cryogenian Period. This gap encompasses the time of final assembly and breakup of the Rodinia supercontinent in this region. We present new petrographic and whole-rock geochemical data and U-Pb ages combined with Hf isotope data of detrital zircons from the volcanosedimentary Chilla beds exposed on the Altiplano southwest of La Paz, Bolivia. The presence of basalt to andesite lavas and tuffs of continental tholeiitic affinity provides evidence of a rift setting for the volcanics and, by implication, the associated sedimentary rocks. U-Pb ages of detrital zircons (n = 124) from immature, quartz-intermediate sandstones have a limited range between 1737 and 925 Ma. A youngest age cluster (n = 3) defines the maximum depositional age of 925 ± 12 Ma. This is considered to coincide with the age of deposition because Cryogenian and younger ages so typical of Phanerozoic units of this region are absent from the data. The zircon age distribution shows maxima between 1300 and 1200 Ma (37% of all ages), the time of the Rondônia–San Ignacio and early Sunsás (Grenville) orogenies in southwestern Amazonia. A provenance mixing model considering the Chilla beds, Paleozoic Andean units, and data from eastern Laurentia Grenville sources shows that >90% of the clastic input was likely derived from Amazonia. This is also borne out by multidimensional scaling (MDS) analysis of the data. We also applied MDS analysis to combinations of U-Pb age and Hf isotope data, namely εHf(t) and 176Hf/177Hf values, and demonstrate again a very close affinity of the Chilla beds detritus to Amazonian sources. We conclude that the Chilla beds represent the first and hitherto only evidence of Rodinia breakup in Tonian time in Andean South America.

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U-Pb zircon geochronology of Neoproterozoic–Paleozoic sandstones and Paleozoic plutonic rocks in the Central Andes (21°S–26°S)

Cited by 8 publications

References 0 publications

Magmatic history and crustal genesis of western South America: Constraints from U-Pb ages and Hf isotopes of detrital zircons in modern rivers

Magmatic history and crustal genesis of western South America: Constraints from U-Pb ages and Hf isotopes of detrital zircons in modern rivers

Pre-Pampean metasedimentary rocks from the Argentinian Puna: Evidence for the Ediacaran margin of Gondwana or the Arequipa–Antofalla–Western Pampeanas block

The missing link of Rodinia breakup in western South America: A petrographical, geochemical, and zircon Pb-Hf isotope study of the volcanosedimentary Chilla beds (Altiplano, Bolivia)

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