The geodynamic evolution of the early Paleozoic Gondwana margin in southern Peru and northern Bolivia - the provenance record of the Ordovician and Devonian siliciclastic strata
Zusammenfassung der Projektergebnisse
In an attempt to trace the provenance of sedimentary detritus and to gain information on the crustal evolution of the Early Paleozoic western Gondwana margin (14°-17°S) we applied a combined in situ U-Pb and Lu-Hf LA-ICP-MS isotope analysis on detrital zircon from 12 Ordovician and Devonian sandstones in southern Peru and northern Bolivia. The sandstones are exposed in the Eastern Cordillera, the Altiplano and the Coastal Cordillera. The sedimentary basins are part of the Peru-Bolivia trough. Few intrusive and extrusive Early Paleozoic rocks indicate that the Ordovician basins developed in a back-arc position, with the arc on the Arequipa Massif in the west and the Amazon craton in the east. This plate-tectonic setting appears to have changed into a passive margin in the Early Devonian. We present zircon U-Pb and Hf isotope data from the coeval or younger siliciclastic strata in order to verify this hypothesis. The U-Pb zircon age distribution of the Ordovician sandstones from the Eastern Cordillera has the most distinctive peak between 0.5 and 0.7 Ga (Brazilian orogeny). Contrastingly, the most prominent U-Pb zircon age peak of the Ordovician sandstone from the Altiplano is at 0.9- 1.2 Ga (Grenvillian orogeny) with a smaller peak at 1.7-1.85 Ga (late Transamazonian orogeny?). The Devonian sandstones from the same locality contain zircons with a major age peak at 0.4-0.5 Ga (Famatinian orogeny). Smaller U-Pb age peaks can be connected to the Brazilian, Grenvillian and Transamazonian orogenies. Zircons of the Devonian sandstones from the Coastal Cordillera have a similar age distribution but the Grenvillian ages, in one case also the Transamazonian ages are more pronounced and the Brazilian ages are less pronounced. Zircons formed during the Brazilian orogeny were derived from the Amazonian craton, those with Grenvillian ages were transported either from the Sunsas belt on the Gondwana continent to the east or from the Arequipa Massif to the west. Zircons related to the Famatinan event most probably derived from the Arequipa Massif, the only place where respective magmatic arc rocks crop out. Thus, for the Ordovician sandstones of the Eastern Cordillera and the Altiplano a eastern source prevailed, and the Altiplano locality was mainly fed from the Sunsas belt. The Devonian siliciclastic strata were mainly influenced by the Arequipa Massif. Minor influences of eastern sources are documented by the presence of Brazilian zircon ages. The in situ Lu-Hf isotope analysis provides information about crustal recycling. Together with the U-Pb zircon ages, crustal evolution paths can be detected. εHf(t) values of the analysed zircons spread between –20 and +12. Juvenil zircons (<300Ma difference between U-Pb age and Hf model age) were formed exclusively at 0.9-1.5 Ga. Hence, during the Brazilian and Famatinian orogenies we only find evidence of recycling of continental crust and no addition of juvenile crust. A striking feature is the common crustal evolution path of zircons formed during the Grenvillian, Brazilian and Famatinian orogenies. This indicates that the Arequipa Massif with a dominance of Famatinian-aged crystalline rocks has a similar origin to the Amazoinan craton from which we suppose the Brazilian-aged zircons derived.
Projektbezogene Publikationen (Auswahl)
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(2005): Initial Results of a Facies Analysis of the Ordovician Siliciclastic Successions of Southern Peru.- 19. Lateinamerika-Kolloquium, Potsdam, Zusammenfassungen, April 2005
Reimann, C., Spiske, M., Bahlburg, H.
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(2005): Initial Results of a Facies Analysis of the Ordovician Siliciclastic Successions of Southern Peru.- Sediment 2005, Bern, July 2005
Reimann, C., Spiske, M., Bahlburg, H.
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(2005): Initial results of a facies and provenance analysis of the Ordovician siliciclastic successions of southern Peru.- Gondwana 12, Mendoza, Argentina, abstracts, 311
eimann, C., Spiske, M.,, Bahlburg, H.
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(2006): Provenance and sedimentology of the Ordovician sedimentary rocks of Southern Peru and Northern Bolivia.- Geologische vereinigung Annual Meeting “Shaping the Earth's Surface: Dynamics, Changing Environments”, September 25-29, Potsdam, Germany, abstracts
Reimann, C., Bahlburg, H., Spiske, M.
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(2006): Sedimentological analysis of the Ordovician and Devonian basins in southern Peru and northern Bolivia.- XIII Congreso Peruano de Geología, Resúmenes, Lima, 17.-20.10.2006
Reimann, C.R., Bahlburg, H., Lopez, S., Carlotto, V.
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(2006): Sedimentology and facies analysis of the Ordovician San José Group (Iparo Formation and Purumpata Formation) and Sandia Formation in the Sandia region, Cordillera Oriental, southern Peru.- Boletín de la Sociedad Geológica del Perú 101, 121-138
Spiske, M., Reimann, C., Bahlburg, H., Carlotto, V.
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(2008): Geochemical and Geochronological data on the provenance of the Devonian Cabanillas Group in the Western and Costal Cordilleras of southern Peru.- XIII Congreso Latinoamericano de Geología, Lima, Peru, 29.09.-03.10.2008, resumenes
Reimann, R., Bahlburg, H., Koijmann, E., Berndt, J., Carlotto, V.
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(2008): Provenance of early Paleozoic sandstones from northern Peru and southern Bolivia: U-Pb evidence of detrial zircons.- 26th IAS Meeting of Sedimentology, Bochum, Germany, 01.-03.09.2008, abstracts
Reimann, R., Bahlburg, H., Koijmann, E., Berndt, J., Carlotto, V.
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(2009): Geodynamic evolution of the early Paleozoic Western Gondwana margin 14°-17°S: U-Pb and Lu-Hf isotope evidence of detrial zircons.- Sedimentation and Tectonics, Bonn 16.-18.02.2009
Reimann, C.R., Bahlburg, H., Kooijman, E., Berndt, J., Carlotto, V.
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(2009): Provenance of Ordovician and Devonian sandstones from southern Peru and northern Bolivia — U-Pb and Lu-Hf isotope evidence of detrital zircons and implications for the geodynamic evolution of the Western Gondwana margin (14°-17°S).- Lateinamerika Kolloquium 2009, Göttingen, 07.04.-09.04.2009, abstracts
Reimann, C.R., Bahlburg, H., Kooijman, Berndt, J., E., Gerdes, A.
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(2009): Timing of accretion and crustal recycling at accretionary orogens: Insights learned from the western margin of South America.- Earth-Science Reviews 97, 227-253
Bahlburg, H., Vervoort, J.D., DuFrane, S.A., Bock, B., Augustsson, C., Reimann, C.
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(2010): Geodynamic evolution of the early Paleozoic Western Gondwana margin 14°-17°S reflected by the detritus of the Devonian and Ordovician basins of southern Peru and northern Bolivia.- Gondwana Research 18, 370-384
Reimann, C.R., Bahlburg, H., Kooijman, Berndt, J., Gerdes, A., Carlotto, V., Lopez, S.
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(2010): Geodynamic evolution of the early Paleozoic Western Gondwana margin 14°-17°S: U-Pb and Lu-Hf isotope evidence of detrial zircons.- 18th International Sedimentological Congress, Mendoza, Argentina
Reimann, C.R., Bahlburg, H., Kooijman, E., Berndt, J., Carlotto, V., Lopez, S.
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(2010: The Role of Crustal Recycling in Accretionary Orogens: the U-Pb Age and Hf Isotope Evidence of Detrital Zircons from the the proto-Andes. AGU Fall Meeting 2010, abstract T13D-07
Reimann, C., Bahlburg, H.
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(2011): The U-Pb and Hf isotope evidence of detrital zircons of the Ordovician Ollantaytambo Formation, southern Peru, and the Ordovician provenance and paleogeography of southern Peru and northern Bolivia.- Journal of South American Earth Sciences 32, 196-209
Bahlburg, H., Vervoort, J.D., DuFrane, S.A., Cárdenas, J., Reimann, C., Carlotto, V.
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(2011): The U-Pb and Hf isotope evidence of detrital zircons of the Ordovician Ollantaytambo Formation, southern Peru, and the Ordovician provenance and paleogeography of southern Peru and northern Bolivia.- Lateinamerika Kolloquium 2011, Heidelberg, GAEA heidelbergensis 18, 39
Bahlburg, H., Vervoort, J.D., DuFrane, S.A., Cárdenas, J., Reimann, C., Carlotto, V.
