Early Carboniferous turbiditic sedimentary rocks in synorogenic basins located on both sides of the Rheic suture in
SW Iberiawere studied for provenance analysis. An enigmatic feature of this suture, which resulted from closure
of the Rheic Ocean with the amalgamation of Pangea in the Late Carboniferous, is that there are no recognizable
mid- to Late Devonian subduction-related magmatic rocks,which should have been generated during the process
of subduction, on either side of it. U–Pb LA–ICP-MS geochronology of detrital zircons from Early Carboniferous
turbidites in the vicinity of the Rheic suture in SW Iberia, where it separates the Ossa–Morena Zone (with
Gondwana continental basement) to the north from the South Portuguese Zone (with unknown/Meguma?
continental basement) to the south, reveals the abundance of mid- to Late Devonian (51–81%) and Early
Carboniferous (13–25%) ages. The Cabrela andMértola turbidites of the Ossa–Morena and South Portuguese
zones, respectively, are largely devoid of older zircons, differing from the age spectra of detrital zircons in
the oldest (Late Devonian) strata in the underlying South Portuguese Zone, which contain abundant Cambrian
and Neoproterozoic ages. Mid- to Late Devonian zircons in the Cabrela Formation (age cluster at c. 391 Ma,
Eifelian–Givetian transition) and Mértola Formation (age clusters at c. 369 Ma and at c. 387 Ma, Famennian
and Givetian respectively) are attributable to a source terrane made up of magmatic rocks with a simple
geological history lacking both multiple tectonic events and older continental basement. The terrane capa-
ble of sourcing sediments dispersed on both sides of the suture is interpreted to have been completely re-
moved by erosion in SW Iberia. Given that closure of the Rheic Ocean required subduction of its oceanic
lithosphere and the absence of significant arc magmatism on either side of the Rheic suture, we suggest:
1) the source of the zircons in the SW Iberia basins was a short-lived Rheic ocean magmatic arc, and
2) given the lack of older zircons in the SW Iberia basins, this short-lived arc was probably developed
in an intra-oceanic environment
