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The Beishan orogenic zone is a key area to understand evolution of the Central Asian Orogenic Belt that is an accretionary factory well‐enough preserved in the Paleozoic. In early Paleozoic, the tectonic mélange zone containing the coherent unit and mélange unit is triggered by the complicated accretionary process of the Beishan area. The early Paleozoic tectonic evolution of the Beishan orogenic zone is investigated in this study using sedimentology and stratigraphic correlations of the lowe Paleozoic deposits. From the Cambrian to the middle Ordovician, this region was characterized by geographically extensive, flat‐bedded siliceous mudstone, indicating the existence of a large ocean basin. The oceanic plate entered the convergence phase in terms of the Wilson Circle during the Middle Ordovician, when numerous magmatic arcs formed along two opposite sides of the ocean. The magmatic arcs became the widest during the Silurian, suggesting that the Hongliuhe‐Niujuanzi‐Xichangjing Ocean (HNX; a southern branch of the Paleo Asian Ocean) was reduced to a small residual ocean in the central Beishan region by that time, and probably lasted till the Carboniferous or later by newly published data. [ABSTRACT FROM AUTHOR]

• Devonian felsic igneous rocks in the Chinese Altai show negative zircon ε Hf (t) values. • The Ordovician Altai accretionary wedge contains ancient crustal components. • Hf-in-zircon spatial-temporal mapping shows isotopic heterogeneity in the Altai wedge. A debate exists on whether the deep crust of the Altai Orogenic Belt contains ancient crustal components. To further address this issue, geochemical analyses and zircon hafnium isotopic measurements were conducted on five Devonian magmatic rocks from the Southern Chinese Altai. Three volcanic rocks have rhyolitic compositions and two other intrusions have granite and granodiorite compositions, respectively. These samples all have calc-alkaline, peraluminous compositions and "arc-related" trace element signatures, marked by enrichment in large-ion lithophile elements relative to many of the high field strength elements. Hf-in-zircon isotopic data for these rocks show variable ε Hf (t) values ranging from −25 to +5, with corresponding T DM c model ages varying from ca. 2.7 to ca. 0.9 Ga. These findings represent the first report describing negative zircon ε Hf (t) values for the Devonian magmatic rocks of the region, documenting magmatic reworking of ancient crustal components. The very similar trace elemental patterns and indistinguishable zircon Hf isotopic characteristics, between the studied magmatic rocks and the pre-existing Ordovician accretionary wedge sediments (the Habahe Group), supports the notion that the magmatic rocks are derived from magmatic reworking of the wedge that contains ancient crustal components. The studied magmatism is synchronous with Middle Devonian anatexis of the Ordovician wedge at low-pressure/high-temperature conditions and extrusion of bimodal volcanic rocks occurred in Devonian extensional basins. These events have been collectively taken as proxies of Devonian lithospheric extension in the Chinese Altai. Integrated mapping of Hf isotopic data for the bulk S-type Devonian magmatism of the Chinese Altai shows different domains with dissimilar Hf isotopic signatures. This further indicates that the magma source, i.e., the Ordovician wedge, is compositionally heterogeneous and contains ancient crustal components. [ABSTRACT FROM AUTHOR]