A review on the tectonic affinity of microcontinents and evolution of the Proto-Tethys Ocean in Northeastern Tibet

Northeastern Tibet, as a core component of the Central China Orogenic Belt, preserves critical evolutionary records of the Proto-Tethys and Paleo-Tethys Oceans, offering significant insights into plate reconstruction, paleontology, and paleoclimate research. It comprises three major orogenic systems – the East Kunlun, North Qaidam, and Qilian orogens – with multiple sutures reflecting complex geological formation processes. While a consensus exists that the Proto-Tethyan basin closed during the Late Ordovician to Early Silurian, leading to the amalgamation of the Qaidam, Olongbuluke, and Qilian blocks, debates persist regarding the tectonic affinities of these blocks and the evolutionary relationship between the Proto-Tethys and Paleo-Tethys Oceans. By integrating published geological records and paleomagnetic datasets, this study investigates the tectonic affinities of these microcontinents and reveals distinct pre-Paleozoic tectonic histories: the Qaidam Block, characterized by a Meso-Neoproterozoic basement, exhibits affinity to the Rodinia supercontinent; the Olongbuluke Block shows close linkages with the North China Block, supported by shared paleomagnetic latitudes and detrital zircon age distributions; and the Central Qilian Block is genetically connected to the South China Block, as evidenced by magmatic-isotopic signatures and detrital zircon data. This study challenges the traditional view that the Kunlun Ocean represented a Precambrian oceanic basin persisting until the Late Triassic–Early Jurassic closure, instead proposing its closure occurred during the Late Silurian–Early Devonian. Additionally, paleomagnetic and detrital zircon data suggest that the Proto-Tethys Ocean closure may be genetically linked to the assembly of the Gondwana supercontinent, with subsequent fragmentation of Gondwana triggered by the opening of the Paleo-Tethys Ocean.