Metamorphic and deformational characteristics recorded by Langzishan Barrovian series rocks within the Jiao-Liao-Ji Orogenic Belt, North China Craton

Orogenesis always involves multiple tectonic events accompanied by metamorphic cycles. The Barrovian metamorphic series often records complicated prograde metamorphism and deformational features, which are crucial for understanding the related orogenic evolution. While Barrovian metamorphism have been widely documented in the Phanerozoic orogenic belts, limited stuides have been conducted on Paleoproterozoic Barrovian metamorphic series. In this contribution, Barrovian metamorphic series extending from biotite to kyanite zones in the middle of Jiao-Liao-Ji Orogenic Belt (JLJOB) from eastern part of North China Craton (NCC) was investigated. The current studies identified the occurrence of polyphase deformation and metamorphism within the Langzishan Barrovian metamorphic series. D1 fabrics are characterized by the development of S1 foliation and L1 lineation in association with greenschist facies metamorphism (M1) that occurrs at ca. 490 ℃ and ca. 5.7 kbar. D2 fabrics that include different folds (F2), S2 crenulation cleavage, S2 foliation and L2 lineation, accompanied by the low amphibolite metamorphism (M2) that occurrs at ca. 670 ℃ and 8.2–8.6 kbar. D3 fabrics involving kink band postdate sillimanite growth that occurrs at ca. 660 ℃ and ca. 6.5 kbar, and predate chlorite occurrence. Monazite U-Pb dating suggests the peak and retrograde metamorphic ages of ca. 1.93 Ga and 1.86 Ga, respectively. Thus, a clockwise pressure–temperature-time-deformation (P-T-t-D) path is established, possibly related to the crustal thickening process. These features are very similar to those documented in Phanerozoic Barrovian metamorphic series, suggesting that a comparable orogenesis mechanism could be shared in the Paleoproterozoic and Phanerozoic.