缅甸掸邦排空市甘山岩体锆石U-Pb测年及地质意义

ZIRCON U-PB DATING AND GEOLOGICAL SIGNIFICANCE OF GANSHAN PLUTON,PAI KONG CITY,SHAN STATE,MYANMAR

甘山岩体呈岩株状出露于缅甸中部岛弧火山构造岩浆岩带内,大地构造属冈瓦纳大陆滇缅陆块群保山-掸泰结合带之保山-掸邦地块。锆石LA-ICP-MS U-Pb定年结果43.67±0.3Ma,形成于古近系始新统,属喜马拉雅期侵入体。显示出高硅、过铝质、富K、Na,贫Ca、Fe、Mg的极成熟“S”型花岗岩特征。为喜山期碰撞造山后板内伸展作用的产物。

The Ganshan pluton occurs as a rock stock in the island arc volcanic tectonic magmatic belt in central Myanmar,which belongs to the Baoshan-Shan State block of the Baoshan-Shantai junction zone of the Yunnan-Myanmar block group in the Gondwana continent.The zircon LA-ICP-MS U-Pb dating result is 43.67±0.3Ma,indicating that it was formed in the Paleogene Eocene and is a Himalayan intrusion.The pluton has the characteristics of extremely mature'S'-type granite with high silicon,peraluminous,enriched in K and Na,and depleted in Ca,Fe and Mg,indicating that it is the product of intraplate extension after collisional orogeny in Himalayan period.