Tectonic affinity of Mesoproterozoic microcontinents in the Central Asian orogenic belt and implications for the evolution of the Mesoproterozoic Earth system

Contrasting the dramatic changes in the preceding and succeeding eras, the Mesoproterozoic era (1.6~1.0 Ga) witnessed environmental and evolutionary stasis. However, during Mesoproterozoic time, accretionary orogeny was intensely operative in the periphery of the Nuna supercontinent after its amalgamation, followed by the extension and breakup of Nuna, and paved the way to the formation of the Rodinia supercontinent. Several Mesoproterozoic microcontinents have been identified along the southern margin of the Central Asian orogenic belt (CAOB) and consist of 1.56~1.36 Ga crystalline basements and greenschist- to amphibolite-facies metamorphosed volcanic-sedimentary rocks, whose tectonic affinity remains controversial. Based on an integrated comparison of basement composition, nature of magmatic activity, and detrital zircon U-Pb ages and Hf isotopes, a western Amazonian affinity in the Nuna’s periphery was established for the Mesoproterozoic microcontinents in the southern CAOB. Reconsidering the multiple proxies of the Earth’s surface and deep systems in the Mesoproterozoic, we emphasize the energetic Mesoproterozoic era, during which the intense accretionary orogeny along the Nuna’s periphery might have stimulated environmental oxygenation and eukaryotic innovation in the Mesoproterozoic. The spatiotemporal correlations between the deep Earth processes and surficial environmental and biotic evolution, along with their primary mechanism, represent critical scientific issues that warrant further in-depth investigation.