Subduction of the Neo-Tethys ridge beneath the Eurasian continent during the Cretaceous

Abstract

Ridge subduction usually has significant influences on the tectonics, magmatic activity and mineralization of the overriding plate because of its special thermal and topographic structures. The Neo-Tethys is a vanished ancient ocean, and thus, its spreading ridge must have been subducted beneath the Eurasian continent. However, where and when the subduction of the Neo-Tethys ridge occurred has not been well constrained. In this study, a Late Cretaceous (∼100 Ma) EW-trending igneous rock belt along the southern margin of the Eurasian continent from the Gangdese terrane to the South China block is recognized based on residual geological records and plate reconstruction. Importantly, these igneous rocks show the characteristics of typical adakites and are consistent with those of adakites derived from partial melting of subducted oceanic crust. Combined with the tectonic evolution of the Neo-Tethys Ocean, ridge subduction was most likely responsible for this adakitic igneous rock belt. In addition, a NS-trending compression event simultaneously occurred in the southern margin of the Gangdese terrane and the South China block during the Late Cretaceous, which agrees well with ridge subduction. The identification of the Neo-Tethys ridge subduction is of great significance for understanding the evolution, magmatism and mineralization of the Neo-Tethys tectonic domain.