Two-phase southward subduction of the Mongol-Okhotsk oceanic plate constrained by Permian-Jurassic granitoids in the Erguna and Xing'an massifs (NE China)

• Published in: Lithos Vol. 304-307; pp. 347 - 361
• Main Authors: Liu, Huichuan, Li, Yinglei, He, Hongyun, Huangfu, Pengpeng, Liu, Yongzheng
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 01.04.2018
• Subjects: A-type granite; Back-arc extension; Continental arc; Erguna Massif; Mongol-Okhotsk Ocean; Mongol-Okhotsk Ocean; Back-arc extension; A-type granite; Continental arc; Erguna Massif
• ISSN: 0024-4937; 1872-6143
• DOI: 10.1016/j.lithos.2018.01.016

Geodynamics of the Mongol-Okhotsk oceanic plate southward subduction are still pending problems. This paper presents new zircon LA-ICP-MS U-Pb age and whole-rock geochemical data for the middle Permian to Middle Jurassic granitoids in the western Erguna and central Xing'an massifs. 267–264 Ma, 241 Ma and 173 Ma I-type granites, and 216 Ma A-type granites were identified in the Erguna and Xing'an massifs (NE China). The I-type granites were produced by partial melting of the lower mafic crust. The 216 Ma A-type granites were derived from partial melting of crustal materials with tonalitic to granodioritic compositions. The 267–264 Ma and 241 Ma I-type granites were generated in an Andean-type arc setting, wheras the 216 Ma A-type and 173 Ma granites were formed in supra subduction extensional setting. We summarized previous age data of the middle Permian to Middle Jurassic magmtaic rocks in the Erguna and Xing'an Massifs and identified two isolated phases of magmatic activity including the ca. 267–225 Ma and ca. 215–165 Ma periods, with a significant magmatic gap at ca. 225–215 Ma. These middle Permian to Middle Jurassic magmatic rocks are closely related to the southward subduction of the Mongol-Okhotsk ocean. A two-stage tectonic evolutionary model was proposed to account for these geological observations in the Erguna and Xing'an massifs, involving Permian to Middle Triassic continuous southward subduction of the Mongol-Okhotsk oceanic plate and Late Triassic to Jurassic slab-rollback and supra subduction extension. [Display omitted] •267–173 Ma I- and A-type granites in Erguna and Xing'an massifs were studied.•Two magmatic ‘flare-up’ at 267–225 Ma and 215–165 Ma were identified.•Their generation was related to the Mongol-Okhotsk oceanic-plate subduction.•A two-stage model involving southward subduction and slab-rollback was proposed.