2024-03-29T01:47:51Zhttp://digital.csic.es/dspace-oai/requestoai:digital.csic.es:10261/188962017-09-22T08:21:58Zcom_10261_91com_10261_8col_10261_344
2009-11-23T09:03:17Z
urn:hdl:10261/18896
An Amazonian Mesoproterozoic basement in the core of the Ibero-Armorican Arc: 39Ar/40Ar detrital mica ages complement the zircon's tale.
Gutiérrez-Alonso, G.
Fernández-Suárez, Javier
Collins, Alan S.
Abad, Isabel
Nieto, F.
Iberia
Detrital mica
Cambrian
Gondwana
40Ar/39Ar geochronology
Ediacaran
The 40Ar/39Ar age data on single detrital muscovite grains complement U-Pb zircon ages in provenance studies, as micas are mostly derived from proximal sources and record low-temperature processes. Ediacaran and Cambrian sedimentary rocks from northwest Iberia contain unmetamorphosed detrital micas whose 40Ar/39Ar age spectra suggest an Amazonian–Middle American provenance. The Ediacaran sample contained only Neoproterozoic micas (590–783 Ma), whereas the Cambrian sample contained three age groups: Neoproterozoic (550–640 Ma, Avalonian–Cadomian–Pan African), Mesoproterozoic- Neoproterozoic boundary (ca. 920–1060 Ma, Grenvillian-Sunsas), and late Paleoproterozoic (ca. 1580–1780 Ma, Rio Negro). Comparison of 40Ar/39Ar muscovite ages with published detrital zircon age data from the same formations supports the hypothesis that the Neoproterozoic basins of northwest Iberia were located in a peri-Amazonian realm, where the sedimentary input was dominated by local periarc sources. Tectonic slivering and strike-slip transport along the northern Gondwanan margin affected both the basins and fragments of basement that were transferred from Amazonian to northern African realms during the latest Neoproterozoic–earliest Cambrian. Exhumation and erosion of these basement sources caused shedding of detritus to the Cambrian basins, in addition to detritus sourced in the continental mainland. The apparent dominance of Rio Negro–aged micas in the Cambrian sandstone suggests the presence of unexposed basement of that age beneath the core of the Ibero-Armorican Arc.
2009-11-23T09:03:17Z
2009-11-23T09:03:17Z
2005-08
artículo
Geology 33(8): 637-640 (2005)
http://hdl.handle.net/10261/18896
10.1130/G21485AR.1
eng
http://dx.doi.org/10.1130/G21485AR.1
closedAccess
Geological Society of America