扬子西北缘鱼洞子杂岩斜长角闪岩研究与早期大陆地壳演化OA

The formation and evolution of the Earth's early continental crust remain a central theme in Pre-cambrian geology.As a key natural laboratory for studying early crustal growth,the Yangtze Block exhibits de-bated regional variations in its early evolutionary history.This study presents integrated field investigations,zir-con U-Pb geochronology,and whole-rock geochemical analyses of amphibolites from the Yudongzi Complex in the northwestern Yangtze Block.The amphibolites yield a metamorphic age of(2 492±22)Ma,recording a sig-nificant tectono-thermal event in the Early Paleoproterozoic.Geochemically,they show light rare earth element(LREE)enrichment and high-field-strength element(HFSE)depletion,indicative of protolith-derived magmas originating from a metasomatized lithospheric mantle.Combined with previous data,these results reveal four ma-jor tectono-thermal episodes in the northwestern Yangtze margin:Meso-to Neoarchean crustal rejuvenation and reworking;Neoarchean juvenile crustal growth and crustal recycling;Early Paleoproterozoic crustal remelting and high-grade metamorphism;and Late Paleoproterozoic regional metamorphism.By synthesizing petrological,geochronological,and zircon Hf isotopic data from basement rocks across the northern,northwestern,and south-western margins of the Yangtze Block,we propose that these regions experienced divergent Archean but conver-gent Paleoproterozoic crustal evolution.The Early to Middle Paleoproterozoic crustal reworking(peaking at 1.90 Ga)likely reflects the amalgamation of isolated ancient micro-blocks to form the proto-Yangtze Craton,syn-chronous with the assembly of the Columbia(Nuna)supercontinent.In contrast,Late Paleoproterozoic vertical crustal accretion was associated with extensional tectonics during supercontinental breakup.These findings pro-vide important constraints on the Yangtze Block's incorporation into global Precambrian supercontinent cycles.