Age and provenance of the Baluntai arc-related complex (NW China): Implications for the middle Silurian − Early Carboniferous accretionary tectonics of the Central Tianshan arc in the southern Altaids

Abstract

The Central Tianshan, in the southern Altaids, is characterized by abundant gneiss–schist complexes. The origins and tectonic affinities of these complexes have been controversial in the past two decades. This systematic detrital zircon study used geological mapping of the Baluntai Complex (BC) in the middle section of the Central Tianshan to address these issues. Geological mapping revealed that the BC is a thrust stack that formed by a series of top-to-north thrust faults. Our 1135 concordant U-Pb detrital zircon dating results suggest that the gneisses, schists, and metasandstones of the BC were formed during the Middle Silurian to Early Carboniferous (ca. 433–346 Ma), rather than the Precambrian, as previously assumed. Detrital zircon age provenance of these samples suggests that they are sourced from a continental arc. Combining our new data, we concluded that the BC was generated in the arc-related basins by the northward subduction of the South Tianshan Ocean and that the Central Tianshan was a typical Japan-type arc in the middle and late Paleozoic.