RT Journal Article
T1 Amazonian Mesoproterozoic basement in the core of theIbero-Armorican Arc: 40Ar/39Ar detrital mica ages complementthe zircon’s tale
A1 Gutiérrez Alonso, Gabriel
A1 Fernández Suárez, Javier
A1 Collins, Alan S.
A1 Abad, Isabel
A1 Nieto, Fernando
AB 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.
PB Geological Society of America
SN 0091-7613, ESSN: 1943-2682
YR 2005
FD 2005
LK https://hdl.handle.net/20.500.14352/52741
UL https://hdl.handle.net/20.500.14352/52741
LA eng
NO Spanish Ministerio de Educacion y Ciencia, Research Projects
NO International Geological Correlation Programme 453.
DS Docta Complutense
RD 1 sept 2024