Paleoproterozoic collision in the Yangtze Craton:Constraint from rutile and zircon UPb dating of the khondalite series in the Kongling ComplexOA

1.Objective Global collisional orogenic events during the Middle to Late Paleoproterozoic(2.1-1.8 Ga)have garnered significant attention due to their potential role in assembling the Columbia supercontinent(also known as Nuna).Having undergone a series of complex subduction-accretion-collision events,the Yangtze Craton(YTC)is critical for understanding the evolution of Columbia supercontinent.However,research remains limited because Paleoproterozoic basement rocks are largely concealed beneath Neoproterozoic to Phanerozoic sedimentary cover.The Kongling Complex,located within the Huangling Dome(HLD)in the northern YTC,preserves evidence of tectonothermal events between 2.1 Ga and 1.8 Ga.Although most scholars agree that a collision event occurred in the YTC during the Paleoproterozoic,the proposed timing varies widely,ranging from 2.15 Ga to 1.95 Ga.The HLD exposes a khondalite series(KS),composed predominantly of metasedimentary rocks,making it a crucial area for investigating the tectonic evolution of the YTC.As a major component of Early Precambrian high-grade metamorphic complexes,the KS provides a distinctive petrological record of collision processes,with its formation directly linked to collisional orogeny.Chronological studies of the KS are thus essential for constraining the timing of collision event.The Kongling khondalite series(KLKS)assemblages are predominantly composed of metapelites(including graphite schists and gneisses),interlayered with metacarbonates(such as marble)and siliceous rocks(including quartzite and leptynite).