The Lhasa terrane is widely regarded as an integral unit that separated from Gondwana in the Carboniferous or late Triassic, but this terrane may more reasonably consist of two subterranes that separated from Gondwana at different times. Here, we describe newly identified early Carboniferous (355–344 Ma) basic and intermediate intrusive rocks in the Xiongcun area, southern Tibet. The basic rocks that yield negative whole‐rock ε_Nd(t) values (−5.04 to −2.94) and zircon ε_Hf(t) values (−9.2 to −1.7), combined with the chemical compositions, indicate that the magmas were derived by the partial melting of an enriched lithospheric mantle in a back‐arc extensional setting. The intermediate rocks yield ε_Nd(t) and ε_Hf(t) values of −5.78 to −5.36 and −9.2 to −4.5, respectively, which suggests that they were likely produced via crust‐mantle mixing. By combining our results with those of previous studies on the Lhasa terrane, we consider that a broad back‐arc rift system, including northern and southern branches, developed along the northern margin of Gondwana under the southward subduction of the Paleo‐Tethys oceanic lithosphere during the early Carboniferous. The northern branch evolved into the Sumdo Paleo‐Tethys Ocean, which led to the separation of the North Lhasa terrane from northern Gondwana during the late Carboniferous. The subsequent northward subduction of the Sumdo Paleo‐Tethys oceanic lithosphere beneath the North Lhasa terrane during the early to middle Permian may have triggered the southern branch to further evolve into the Neo‐Tethys Ocean and eventually may have resulted in the South Lhasa terrane separating from Gondwana.

《地球科学》(ISSN 1000-2383;CN42-1874/P) (原刊名《地球科学——中国地质大学学报》ISSN 1000-2383;CN42-1233/P)，创刊于1957年，是由教育部主管、中国地质大学主办的综合性地学学术理论期刊，月刊，2015年改名为《地球科学》,她以反映中国地质大学教学与科研最新的、高水平的基础地质、应用地质、资源与环境地质及地学工程技术研究成果为主要任务。