Tectonic provenance of the Bayandor sandstones (late Neoproterozoic) in the Chopoghlu section, Northwest Iran

The tectonic setting of Iran during late Neoproterozoic time is not fully understood, with proposals ranging from passive margin (Iran as a part of Afro-Arabian platform) to active margin (Iran as a part of Peri-Gondwanan terranes). Tectonic provenance of Bayandor Formation, which is deposited during this time, can provide constraints on late Neoproterozoic tectonic evolution of Iran. The Bayandor Formation in the Chopoghlu section is mainly composed of dark purple to red siliciclastics, mainly mudrocks and minor sandstones (~400m). The sandstones contain abundant quartz, volcanic lithic fragments (mainly andesite and rhyolite), and feldspars and have an average composition of Q44F30RF26 (lithic arkose to arkosic litharenite), Qt47F30L23 and Qm37F30Lt33. The data presented here clearly indicate that the Bayandor sandstones were derived from magmatic arc sources dominated by relatively felsic/intermediate volcanic rocks and unroofed granodiorite intrusives. Textural and compositional immaturity of Bayandor sediments, along with sub-angular to angular shapes of labile grains such as volcanic rock fragments, suggest local derivation from surrounding exposed basement (proximal sources), and deposition on an active continental margin. These results provide new constraints on subduction scenario during this time interval in Iran, as a part of the Peri-Gondwanan terranes.