부산대학교 도서관

U-Pb detrital zircon data from the Baixo Alentejo Flysch Group in the South Portuguese Zone show significant age differences between formations. The Visean Mertola Formation and Serpukhovian to early Bashkirian Mira Formation are dominated by zircons in the 316u388?Ma age range, whereas the late Bashkirian to late Moscovian Brejeira Formation is dominated by zircons with an age range of 498u687?Ma. Detrital zircons spanning an age range of 0.9u1.1?Ga are present in the Brejeira Formation but are absent in the Mertola and Mira formations. Detrital zircon ages of the Mertola and Mira formations indicate provenance from an extra-basinal source (OssauMorena Zone) with a minor intra-basinal contribution (South Portuguese Zone). The abundant presence of detrital zircon with age ranges of 500u750 and 0.9u1.1?Ga in the Brejeira Formation suggests a sediment source from the AvalonuMeguma terranes with limited recycling from the SW Portugal Domain. The different inferred source areas for the Baixo Alentejo Flysch Group formations are attributed to the presence of a forebulge that was formed in Mid-Visean times during the foreland phase of the South Portuguese Zone. The forebulge acted as a physical barrier separating sub-basins that accumulated the MertolauMira and Brejeira sediments respectively.