Provenance of the Oligo-Miocene Zivah Formation, NW Iran, assessed using heavy mineral assemblage, detrital clinopyroxene and detrital apatite geochemistry

Heavy mineral analysis and geochemical analysis of detrital clinopyroxene and apatite have been used to determine provenance and tectonic setting of the Oligocene-Miocene Zivah Formation, in three outcrop sections from the Moghan area in northwest Iran. The composition of assemblages from the Zivah sandstones have a majority of clinopyroxene, apatite, biotite and opaque minerals with minor amounts of hornblende, zircon, garnet and epidote. The abundance of a mafic heavy-mineral suite such as clinopyroxene relative to metamorphic and felsic heavy mineral suites such as epidote, garnet and zircon indicates a convergent tectonic setting. Geochemistry of detrital clinopyroxenes from the Zivah Formation also indicates that these detrital grains probably crystallized from calk-alkaline magmas. They also show orogenic tectonic setting at the time of Zivah deposition. This is consistent with the derivation of these sediments from areas with calc-alkaline volcanic rocks like Talysh and Lesser Caucasus as a result of Caucasus orogeny. Compositions of detrital apatites of the Zivah Formation are also consistent with the widespread distribution of unfractionated (mafic / intermediate) volcanic rocks of both alkaline and calc-alkaline composition in the Lesser Caucasus and Talysh.