L6型普通球粒陨石茂名的岩石学、地球化学和年代学研究OA

The Maoming meteorite,an L6 ordinary chondrite from a witnessed fall in 2025,is characterized by fresh preservation,negligible terrestrial weathering(W0),and a low degree of shock metamorphism(C-S2).In this study,the petrography,geochemistry,and phosphate U-Pb chronology of the Maoming meteorite were systematically investigated using scanning electron microscopy,bulk major-and trace-element analyses,and in-situ SHRIMP U-Pb dating.The sample exhibited indistinct chondrule boundaries and extensive silicate recrystallization.Its mineral assemblages,petrographic textures,and major-and trace-element compositions were comparable to those of previously reported L6 ordinary chondrites.The rare earth element pattern was nearly flat,with no significant Eu anomaly.Chlorapatite yields a weighted mean 207Pb/206Pb age of(4 480±12)Ma,which was younger than previously reported ages for weakly shocked L6 ordinary chondrites.Moreover,its U-Pb isotopic system showed no evidence of reset related to the～470 Ma breakup of the L-chondrite parent body.These results indicate that the Maoming meteorite was derived from the middle to deep interior of the L-chondrite parent body,where it underwent extensive thermal metamorphism followed by slow cooling,without significant melt differentiation.Therefore,it provides a critical end-member constraint on the late-stage cooling history of L6 ordinary chondrites.