Hf Isotopes and Detrital Zircon Geochronology of the Silasia Formation, Midyan Terrane, Northwestern Arabian Shield: An Investigation of the Provenance History

Abstract

U–Pb ages and Hf isotopic data from detrital zircon of the Silasia Formation in the Midyan Terrane record evidence for the provenance and tectonic evolution of the northern Arabian Shield. Given that the youngest acknowledged age of these detritus sediments is 735 ± 13 Ma, it is likely that the Silasia Formation was deposited during the closure of the Mozambique Ocean. The U–Pb ages define a major Mesoproterozoic peak, with two minor peaks of Neoproterozoic and Archean age. Combined with zircon Hf isotopic compositions, the sedimentary detritus of the Silasia Formation was mainly derived from source rocks formed during the Grenville Orogeny during the assembly of Rodinia, with a minor contribution from Archean and Paleoproterozoic crustal material, in addition to a limited arc-basement supply related to the early Mozambique Ocean. The youngest Concordia age of 735 ± 13 Ma with highly variable εHf_(t) values (11 to −35) indicates a complex mixture of sources from juvenile to extremely ancient. The Concordia ages at 1113 ± 11 and 1046 ± 10 Ma have positive hafnium isotope signatures (up to +10.45) that are consistent with juvenile source rocks formed during the Grenville Orogeny. Several detrital zircons with ages of 2622 ± 22 Ma and 2690 ± 7 Ma are similar to those reported in Yemen, whereas 1818 ± 19 Ma, 2071 ± 8 Ma and 2001 ± 19 Ma Paleoproterozoic ages are similar to dated outcrops in the Khida terrane in the eastern Arabian Shield.