腾冲上新统芒棒组地质时代及沉积环境

摘要：腾冲地区新生代地层分布广泛，其中又以芒棒组出露较为完整，由河流相、湖泊相及沼泽相碎屑岩夹火山岩中火山沉积岩组成，含丰富的植物化石和硅藻化石。依据化石研究及用K-Ar、Rh-Sr法测获同位素年龄，芒棒组应属新近纪上新世。植物化石显示腾冲地区上新世时期气候，比现今亚热带炎热干燥气候较温凉而湿润，反映该区从新近纪上新世至第四纪，气候有从凉变暖的演变趋势。

THE GEOLOGICAL PERIOD AND SEDIMENTATION ENVIRONMENT MANGBANG FORMATION IN TENGCHONG AREA,YUNNAN

The Cenozoic strata are widely distributed in Tengchong area. And the Mangbang Formation of them is well outcropped, which is composed of clastic rocks of river-, lake- and marsh-facies with volcanic rock and volcanic sedimentary rock interbeds and abundant flora, diatom fossils. The Mangbang Formation must be classified into Pliocene of Neogene according to the flora, diatom fossils and K-Ar, Rb-Sr isotope dating. The flora fossils in it show that the climate of Tengchong in Pliocene is cooler and wetter than the present hot dry subtropical climate, which reflects the climate evolution from the cool to the hot in Tengchong area since Neogene till Quaternary.