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• Three episodes granitic magmatism at ca. 1420 Ma, ca. 900 Ma and 780–750 Ma were identified in drill cores from the Qaidam basin. • Ca. 1.8–1.1 Ga, 1.0–0.9 Ga and 850–750 Ma three tectonic-thermal events of the Qaidam block correspond to the fragmentation of Columbia and the assembly and breakup of Rodinia. • The Qaidam block and Tarim craton likely constituted a unified block, and located at interior of Columbia but peripheral of Rodinia during Meso–Neoproterozoic. As a micro-continent lying at the junction of the North China, Yangtze, and Tarim Cratons in northwest China, the composition and tectonic-thermal history of the Qaidam Block not only are crucial for determining its tectonic attribute and relationships with surrounding cratons, but also can provide key constraints on convergence, fragmentation, and paleogeographic reconstruction of Columbia and Rodinia. In this study, systematic petrology, geochemistry, and zircon U–Pb–Hf isotope analyses were conducted on newly discovered Meso-Neoproterozoic granitic rocks from drill cores in the Qaidam basin and three stages granitic magmatism at ca. 1420 Ma, ca. 900 Ma and 780–750 Ma are yielded. The ca. 1420 Ma granitic rocks exhibit characteristics of highly fractionated I-type granites, with high Yb but low Sr contents, low Sr/Y and La/Yb ratios, high zircon saturation temperatures (774–831 ℃), and positive ε Hf (t) values (–0.04 to +11.35) with T DM2 values of 2178–1468 Ma, suggesting that they were mainly derived from the ancient crust with mantle magma input under an extensional setting. The ca. 900 Ma granitic rocks have high A/CNK values (1.01–1.21) and variable zircon ε Hf (t) values (–1.93 to + 6.58) with T DM2 ages between 1402 and 1910 Ma, indicating they are S-type granites formed by partial melting of sedimentary rocks in thickened crust. The ca. 780–750 Ma granites have high Zr + Nb + Ce + Y contents, 10000* Ga/Al ratios, and crystallization temperatures (mean = 808 ℃), belonging to the A 1 -type granite formed in a continental rift setting. Combined with the previous researches, the Meso-Neoproterozoic tectonic-thermal events in the Qaidam Block can be divided into three stages, 1.8–1.1 Ga, 1.0–0.9 Ga and 850–750 Ma, corresponding to the fragmentation of Columbia, and the assembly and breakup of Rodinia, respectively. Comparing the Qaidam Block with the surrounding blocks and the major cratons in Columbia and Rodinia, it is considered that the Qaidam Block was splited from the Tarim Craton and they may have occupied an interior position in Columbia but a peripheral position in Rodinia, connecting to the India and East Antarctica. [ABSTRACT FROM AUTHOR]