From Gondwana rifting to Alpine orogeny: Detrital zircon geochronologic and provenance signals from the Kopet Dagh Basin (NE Iran)

Abstract

The Kopet Dagh mountains in NE Iran exhibit a 7-km-thick continuous sedimentary sequence recording detritus from exposed surrounding terranes from the last 175 Ma. This work presents a multi-disciplinary geochronologic and provenance analysis in an attempt to identify and date major geologic events along the northern segment of the Tethys and reconstruct the regional tectonic history from Gondwana-related rifting until the Alpine orogeny. Sandstone framework, heavy mineral analysis, U-Pb dating of detrital zircons, and Hf-isotope ratio measurements on dated zircons from Triassic to Paleocene sandstones indicate three main tectonic events that include Early Silurian intracontinental rifting (opening of Paleo-Tethys), Early Carboniferous rifting of a back-arc basin (Aghdarband Complex), and Late Triassic collisional to post-collisional magmatism (Paleo-Tethys collision). Mineralogical and age peak considerations indicate that detritus was supplied from the south into the extensional Kopet Dagh Basin during Middle Jurassic, while Cretaceous to Paleocene sandstones show signs of increasing recycling.