Neoarchaean granitoid complexes in the Laoling area, Jilin Province, North China Craton: transition from mantle plume to plate subduction

The application of zircon U-Pb geochronology, geochemistry, and Hf isotope analysis to the granitoid complex in the Laoling area of southern Jilin Province (SJP) in the northeastern part of the North China Craton can provide valuable insights into its petrogenesis and tectonic setting. The predominant rock types found in SJP granitoid complex encompass monzonitic granite, tonalite, and various other varieties. The zircon U-Pb dating results indicate that the monzonitic granite (N20HT-1–1) crystallized at 2499 ± 4.2 Ma, the tonalite (N20HT-2–1) at 2722 ± 30 Ma, and the mylonitized tonalite (PH01-14–2) at 2505 ± 15 Ma, the monzonitic granite (DA19-3) at 2563 ± 16 Ma. Through the analysis of Hf isotopes, two-stage depleted mantle model ages, and elemental geochemistry, the inference can be made that tonalite enriched with the residual magmatic zircon are originally formed by the partial melting of ~3.4 Ga basaltic crust. Besides, the magmas of the monzonitic granite and mylonitized tonalite were sourced from the partial melting of potassium-rich basaltic rocks and a small amount of metasedimentary units and TTG suite rocks within the lower crust of the Meso- to Neoarchaean (3.1–2.7 Ga) continental framework. Based on this study and previous findings, it can be concluded that there are primarily three phases of magmatic activity in SJP: During the Mid Neoarchaean period (~2.7 Ga), the basaltic crust underwent partial melting due to the tectonic influence of a mantle plume, resulting in the formation and emplacement of tonalite-trondhjemitic magma. In the Late Neoarchaean period (~2.6 Ga), a transition occurred from mantle plume to plate subduction. It was during this time that monzonitic granite began to develop, suggesting the initiation of the plate tectonic system. At the End Neoarchaean period (~2.5 Ga), a significant amount of potassium-rich granite erupted as a result of plate subduction processes. Furthermore, it is worth noting that the tectonic setting for monzonitic granite in SJP indicates a post-orogenic extensional environment, implying that felsic magmatism during this phase is associated with dynamic processes related to arc-continent collision caused by plate subduction followed by subsequent post-collision extension.