临沧地体亲缘性及南段组物源——来自泥盆纪-石炭纪南段组碎屑锆石U-Pb年龄的证据

The relationship between Lincang block and provenance of Nanduan Formation:Evidence of detrital zircon U-Pb dating from metasandstone of Devonian-Carboniferous Nanduan Formation

摘要: 对临沧地体泥盆纪-石炭纪南段组的沉积岩开展碎屑锆石LA-ICP-MS U-Pb定年研究结果表明，所有样品的U-Pb年龄谱存在3个主要峰值：泛非期（530~680Ma）、晚格林威尔期（900~980Ma）和早格林威尔期（1100~1300Ma）。次要峰值年龄为1550~1730Ma和2350~2630Ma，反映了物源区构造-岩浆事件的复杂性。南段组碎屑岩锆石年龄图谱明显区别于思茅地块泥盆纪-石炭纪碎屑锆石年龄图谱，临沧地块南段组碎屑锆石的年龄表明其物源来自东冈瓦纳超大陆，临沧地体应该是来自东冈瓦纳北缘的微地块，这也与其生物特征相吻合。

Abstract: U-Pb ages of detrital zircons of Devonian-Carboniferous Nanduan Formation from Lincang block define three distinctive age peaks in older Grenvillian (1100~1300Ma), younger Grenvillian (900~980Ma) and Pan-African (530~680Ma), and two subordinate group in 1550~1730Ma and 2350~2630Ma, suggesting that the provenance of sediments had multi-source and complex characteristics. The age spectrum is obviously different from detrital zircon age spectrum of the Devonian-Carboniferous sediments of Simao block, which indicates that the sediments of Nanduan Formation came from East Ganwana supercontinent, and the result is indicated by paleobiology which shows a genetic relationship between East Ganwana and paleo-Tethys in southwest Yunnan.