New Geochemical and Age Data on the Bajgan Complex (Makran Accretionary Prism, SE Iran): Implications for the Redefinition of Its Tectonic Setting of Formation from a Paleozoic Continental Basement to a Cretaceous Oceanic Domain

The Bajgan Complex (BC) in the North Makran Domain (Makran Accretionary Prism, SE Iran) has been considered a remnant of a Paleozoic metamorphic continental basement detached from the southernmost edge of the Lut Block. We present here new geochronological and petrological data on metamorphic rocks from this Complex, intending to assess the age and tectonic--magmatic setting of the formation of their magmatic protoliths. The BC consists of meta-ophiolitic tectonic slices, including meta-peridotites, meta-gabbros, meta-plagiogranites, and meta-basaltic lavas. Whole rock geochemical data show that their magmatic protoliths include: (1) magmatic rocks showing both normal (N-) and enriched (E-) MORB affinities, as those formed at mid-ocean ridge settings; (2) basalts showing alkaline ocean island (OIB) chemistry similar to those formed in seamounts. Zircon U-Pb dating indicates magmatic ages of the protoliths from 161--114 Ma (Late Jurassic--Early Cretaceous). Our new data suggest that the interpretation of the BC as a Paleozoic continental ribbon should be abandoned. Instead, it represents a long-lived (at least {\textasciitilde}50 My) Cretaceous oceanic lithosphere whose composite chemistry and petrogenesis indicate that it was characterized by mantle plume activity and plume--ridge interaction processes. Similar rock associations and procedures have been documented in many other Cretaceous ophiolites of the North Makran, suggesting that the magmatic protoliths of the Bajgan meta-ophiolites were most likely formed in the same oceanic basin.