揚子西南緣新元古代早期構(gòu)造熱事件

——來自撮科雜巖楣石U-Pb年代學(xué)的新證據(jù)

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[分類號］P597 [文獻標(biāo)志碼］A

Abstract：Thespatiotemporal framework of early Neoproterozoic tectonothermal events incentral Yunnan （Dianzhong area）holds critical significance forreconstructing the tectonic evolution and metallgenic processes in the southwestern Yangtze Block during the assmbly of the Rodinia supercontinent.This study conducts LA-ICP-MS U-Pb geochronology and in situ trace element analysis of zircon and titanite in a gneisic granite sample from the Cuoke Complex.The results show that the zircons exhibit typical oscilatory Zoning and high Th/U ratios （0.56～1.46） ， indicating a magmatic origin. Their weighted mean 207Pb/206Pb age of 2334±18 Ma （MSWD=0.44） ） constrains the formation time of the gneisic granite.The titanite U-Pb ages can be divided into two groups， with 207Pb corrected weighted mean 206Pb/238U ages of 987±7 Ma （MSWD=0.50） and 932±8 Ma （MSWD=1.05） ， respectively. Their low Th/U ratios，enrichment in heavy rare earth elements and weak Eu anomalies， suggest a metamorphic origin，indicatingthat the Cuoke Complex underwent at least two episodes of metamorphism during the early Neoproterozoic.Integrated with regional geological data，this study further confirms that the southwestern margin of the Yangtze Block witnesed extensive early PaleoproteroZoic magmatic activity and underwent multiple episodes of regional metamorphism during the assembly of both the Columbia and Rodinia supercontinents，while demonstrating a pronounced spatiotemporal coupling among early Neoproterozoic magmatism， metamorphism， and mineralization events in this region.

Key words： titanite U-Pb age；tectonothermal events； Cuoke Complex；Neoproterozoic；Yangtze Block

鋯石因高鈾、低鉛以及U-Pb體系封閉溫度高 Φ>800Φ′C， 、化學(xué)性質(zhì)穩(wěn)定，成為地質(zhì)年代學(xué)研究的首選礦物（Sunetal.，2012；Zhao etal.，2020）。（剩余32235字）