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The vast eastern-Tethyan oceanic domain that throughout the Mesozoic extended between Gondwana and Eurasia was a puzzle of larger and smaller microcontinents separated by larger and smaller oceans, the paleogeographic reconstruction of which poses major challenging problems. This review article summarizes the available stratigraphic, sedimentological, petrological, geochronological, geochemical, tectonic, and paleomagnetic evidence on the Bangong-Nujiang suture zone and adjacent geological domains now at the heart of the Tibetan Plateau, with the final aim to reconstruct the history of the Bangong-Nujiang Ocean from its birth to its growth and final demise. The vivid debate on these highly controversial geological issues touches on several key problems in plate tectonics, including the birth of an ocean, the nature of microcontinents and seamounts, the initiation of oceanic subduction, the implications of subduction polarity, and the timing of continental collision. Rifting between South Qiangtang and the Lhasa blocks took place in the Early to Middle Permian. The Bangong-Nujiang Ocean was still narrow in the Late Permian. The Triassic saw the rapid northward drift of South Qiangtang and active sea-floor-spreading in the Bangong-Nujiang Ocean, which reached a maximum north–south width of ~4000 km in about 50 million years. In the Early Jurassic (~190–180 Ma), Bangong-Nujiang oceanic lithosphere began to subduct northward. After some 30–40 million years of oceanic subduction, documented by arc magmatism and high-pressure metamorphic rocks, the Bangong-Nujiang Ocean closed its northern branch (the Dongqiao-Amdo ocean) in the latest Middle Jurassic (166–163 Ma), when the Amdo and Dongkacuo microcontinents collided with South Qiangtang. The southern oceanic branch (the Beila-Nagqu ocean) closed in the latest Jurassic (150–145 Ma) at the onset of collision between the Lhasa and Qiangtang blocks. Early Cretaceous (140–120 Ma) syncollisional arc-type magmatism was widely distributed in the Lhasa-Qiangtang collisional zone. At earliest Late Cretaceous time, the complete demise of seaways and the transition to widespread deposition of continental red beds along the Bangong-Nujiang suture zone marked the onset of intracontinental convergence leading to initial uplift of the Tibetan Plateau. • Critical review of geological data related to the Bangong-Nujiang Ocean from its birth to its growth and demise. • Bangong-Nujiang Ocean opened in the Early Permian and started to subduct northward -~190–180 Ma. • Dongqiao-Amdo and Beila-Nagqu oceans closed at 166–163 Ma and 150–145 Ma, respectively. [ABSTRACT FROM AUTHOR]

Abstract: Bulk-rock major and trace element, Sr–Nd–Hf isotope, zircon U–Pb age, and zircon Hf isotopic data of the Late Cretaceous Zhuogapu volcanic rocks in the northern Lhasa subterrane provide a new insight into tectonic processes following the collision of the terrane with the Qiangtang zone. SHRIMP zircon U–Pb dating reveals that the Zhuogapu volcanic rocks crystallized at ca. 91Ma, postdating the development of a regional angular unconformity between the Upper Cretaceous and the underlying strata in the Lhasa–Qiangtang collision zone. Compared to the Andean arc-type andesites and dacites, the Zhuogapu volcanic rocks are characterized by higher MgO of 2.78–5.86wt.% and Mg# of 54–64 for andesites and MgO of 2.30–2.61wt.% and Mg# of 55–58 for dacites. Eight andesite samples have whole-rock (87Sr/86Sr)i of 0.7054–0.7065, εNd(t) of −3.2 to −1.7, and εHf(t) of +3.8–+6.4, similar to those of the three dacite samples with (87Sr/86Sr)i =0.7056–0.7060, εNd(t) of −2.7 to −2.2, and εHf(t) of +5.6–+7.0. Thirteen analyses from a dacite sample give positive zircon εHf(t) of +5.6 to +8.7. These signatures indicate that the Zhuogapu Mg-rich andesites were most likely derived from partial melting of a delaminated mafic lower crust (including the lowermost crust straddling the northern and central Lhasa subterranes) that led to the generation of the Zhuogapu primary melts with adakitic signatures and small negative εNd(t). Such melts subsequently experienced interaction of melt-asthenospheric mantle peridotite followed by the modification of highly fractionated magmas in shallow crustal magma chamber. Hornblende-controlled fractionation results in the change of geochemical composition from Mg-rich andesitic to Mg-rich dacitic magmas. Field observations, together with geochronological and geochemical data, indicate that the Zhuogapu Mg-rich volcanic rocks and coeval magmatism in the northern Lhasa subterrane may be the result of thickened lithospheric delamination following the final Lhasa–Qiangtang amalgamation. [Copyright &y& Elsevier]