P−T evolution of metapelitic and metamafic rocks from Northern Liaoning: Implications on the Neoarchean tectonic regime of the North China Craton

Abstract

The Archean basement rocks in the Eastern Block of the North China Craton have undergone extensive granulite-facies metamorphism during the late Neoarchean to Paleoproterozoic. However, the geodynamic process and associated tectonic regime of this area remain poorly understood. The Qingyuan area of Northern Liaoning, located in the nucleus of the Eastern Block, plays a crucial role in unraveling the tectonothermal evolution by reconstructing its metamorphic history. Previous studies have mainly focused on the northern part of the area, while the tectonothermal evolution of the southern part remains unknown. In this study, we utilized petrography, phase equilibria modeling, and geochronology to constrain the pressure−temperature−time (P−T−t) paths of representative metapelite and metabasite samples of the area. Our results indicate that both samples have recorded anticlockwise P−T−t paths. The peak condition for the metapelitic rock sample 22QY02-9 is 10.0−11.2 kbar/800−815 °C. U-Pb zircon and monazite dating results indicate a post-peak metamorphic age of ca. 2470−2450 Ma. Metamafic rock sample 22QY04-3 reaches the ultrahigh temperature peak metamorphic condition of 11.5−12.5 kbar/920−950 °C, which is consistent with the results obtained from the ternary-feldspar thermometry calculations. U-Pb zircon dating reveals a cooling age of metamorphism at ca. 2487 Ma. By combining the data from this study with previous research, a sagduction model, operating under a non−plate tectonics regime, appears to be the most promising explanation for the most prevalent geological phenomena in the Neoarchean North China Craton.