Geochronology, Petrogenesis, and Tectonic Significance of the Neoproterozoic Diabase in the Jinkouhe area, Western Sichuan Province

Key words: 
• Neoproterozoic /
• Diabases /
• Geochemistry /
• Nature of mantle sources /
• Tectonic setting

Abstract: [Objective] An suite of Neoproterozoic diabase dykes is extensively exposed in the Jinkouhe area, western Sichuan Province, offering crucial insights into the tectonic evolution of the western Yangtze Craton. These diabases bear key implication for understanding the early tectono-magmatic history of the Yangtze Craton and its relationship with the assembly and fragmentation of the Rodinia supercontinent. [Methods] SHRIMP zircon U-Pb geochronology and whole-rock geochemistry analyses were conducted on the Jinkouhe diabases. [Results] SHRIMP zircon U-Pb dating of the diabase samples yields an age of 823 ± 10 Ma (MSWD = 1.30, n = 10). The diabases are classified as tholeiitic basalt series, displaying Nb-Ta depletion and negative Eu anomalies. Their geochemical signatures are indicative of both island arc and intraplate basaltic affinities. [Conclusion] The Jinkouhe diabases are interpreted to may have been originated from partial melting of a spinel-garnet lherzolite mantle source, which was metasomatized by subduction-related melts. Together with regional geological data, it is proposed that these diabases were most likely formed within a post-collisional extensional setting, reflecting tectonic processes associated with the final amalgamation of the Yangtze Craton in the context of the Rodinia supercontinent assembly.