Petrology of early cambrian aged karameşe metagranitoids (Yusufeli-Artvin, NE Türkiye)

We document new Cadomian age and isotope data from the Sakarya Zone. These data are the first report confirming the presence of the Precambrian basement and well-preserved Cadomian terranes. We represent zircon trace elements, zircon U-Pb geochronology, bulk-rock geochemistry, Nd isotopes, and zircon Hf isotopes from the Karameşe metagranitoid in the Artvin (Yusufeli) area, NE Turkey. The zircon U–Pb age data yielded by LA-ICP-MS demonstrate that the Karameşe metagranitoid should have intruded into the Precambrian basement units throughout Early Cambrian (ca. 534–530 Ma). The metagranitoid is made up of S-type granites, with high modal content of muscovite (10%). The samples show highly peraluminous and medium-K calc-alkaline geochemical affinities. They possess low REE concentrations and a slight positive Eu anomaly. The samples have negative Nd(t) of -4.76 to -2.90 and εHf (t) of -4.75 to -1.08 values, slightly light LILEs enrichments, and HFSEs depletions. These reveal that the metagranitoid was generated through muscovite dehydration melting of metasedimentary source. We argue that the generation of the S-type granitoid was originated in the continental extensional basin that shifted from convergent to intra-continental setting. Then, we propose that the Early Palaeozoic intrusive along the eastern Sakarya Zone is mainly an expression of crustal thinning in the Cadomia orogenic belt at the northern Gondwana, with the tectonic turnover from convergent margin to crustal extension possibly induced by break-off of Iapetus oceanic lithosphere during the time of the Ediacaran-Cambrian boundary.