Comment on “Neotethyan subduction ignited the Iran arc and back-arc
differently” by Shafaii Moghadam et al. (2020)
Abstract
Shafaii Moghadam et al. (2020) contribute important new data on Late
Cretaceous-Tertiary subduction- related magmatism in Iran, but their
plate convergence model, wherein Neotethyan subduction begins in
mid-Cretaceous time (c. 100 Ma), overlooks well established facts
relating to the tectonic history of Neotethys, in regard to global plate
reconstructions, paleolatitude data, the regional stratigraphy,
geochronology and geochemistry, and metamorphic history. Based on their
model, Neotethys subduction beneath Eurasia began at
~100 Ma, meaning that the Neotethys was spreading and
bounded by opposing passive margins during Jurassic and Early Cretaceous
time, for ~100 Ma prior to their proposed onset of
Neotethyan convergence. Consequently, their subduction model contradicts
(1) the Indian Ocean spreading history derived from magnetic anomalies;
(2) continental paleolatitude data from paleomagnetism; (3) sedimentary
and igneous evolution of the Mesozoic continental margins in Arabia and
southern Asia, (4) the age and geochemistry of Jurassic igneous rocks in
southernmost Eurasia; and (5) the preservation of Early to Middle
Jurassic eclogite metamorphism and exhumation on the northern side of
the Arabia-Eurasia suture. Reconciliation of each of these omissions and
contradictions of their model would be welcome, and perhaps an advisory
that readers may wish to evaluate their concept of Cretaceous subduction
initiation with due circumspection.