Singularity Analysis of Volcanic Ages and Implications for Tectonic Setting in the Mesozoic, Great Xing’an Range, Northeast China

Abstract

Frequency distribution of zircon U–Pb ages has been commonly utilized to interpret the age of a magmatic event. Anomalies in age peaks are related to plate movement caused by mantle convection during the formation of supercontinents and continent crust growth. In this paper, a singularity analysis method (frequency anomalies) is used to analyze a dataset (n = 823, discordance lower than 10%) of zircon U–Pb ages from the Great Xing’an Range (GXR), in order to characterize the causal relationship between age transitions and Pacific Plate subduction. The numberage plot result shows that there is a peak around at 125 Ma, and the log–log plot reveals that there are two transitional ages (knee points) at 125 Ma and 145 Ma. The age densities of the peak at 125 Ma and the transition at 145 Ma can both be fitted by power law functions, which indicate transitional ages have the characteristic of singularity. Combined with the subduction geological background in the late Mesozoic, the possible singularity mechanisms corresponding to the age peak at 125 Ma and the transition at 145 Ma are slab rollback and slab breakoff of the Pacific Plate, which is consistent with conclusions from geology and geochemistry. This result suggests that singularity analysis can be used as a new method to quantitatively characterize volcanic activities and tectonic setting in geological processes.

Editorial for the Special Issue “Mineral Textural and Compositional Variations as a Tool for Understanding Magmatic Processes”

“…A singularity analysis (frequency anomalies) is also applied to U-Pb ages of zircons from the Great Xing'an Range to characterize the causative relationship between age abnormality and Pacific Plate subduction [3]. Data interpretation is consistent with independent geological and geochemical constraints, thus emphasizing the importance of singularity analysis for quantitative characterization of the time scales involved in long-term volcanic activity and past tectonic regimes [3].…”

“…The geochronological and geochemical signatures of adakitic granodiorites and Nb-enriched basalts from the Xiaozhenzhu Seamount outline contemporaneous formation of these products during northward subduction of the proto-South China Sea along the SE Asian continental margin in the Early Cretaceous [2]. A singularity analysis (frequency anomalies) is also applied to U-Pb ages of zircons from the Great Xing'an Range to characterize the causative relationship between age abnormality and Pacific Plate subduction [3]. Data interpretation is consistent with independent geological and geochemical constraints, thus emphasizing the importance of singularity analysis for quantitative characterization of the time scales involved in long-term volcanic activity and past tectonic regimes [3].…”