摘要
云南省怒江以西的地域,本文称之腾冲-梁河地区。区内晚第三纪盆地含铀矿资源,而盆地的地层划分和对比尚存在不少疑议。本文从沉积学、古生物、标志层和同位素年龄等方面综合分析,认为区内各大型盆地发育了上新世早期至晚期的沉积,而小盆地沉降较晚,发育上新世中期至晚期的沉积。龙川江盆地和梁河盆地中的最老的火山岩,其层位分别按近芒棒组和南林组的底部,但同位素年龄值仅7.19±1.11Ma和7.2Ma,明显新于上新世下限年龄值10Ma。因此,区内盆地最早沉积为上新世早期,南林组与芒棒组同期,均为上新世。
The region to the west of Nujiang river in western Yunnan is called “Tengchong—Lianghe region”for short. The uranium mineral resources are contained in Neogene Period basins of this region, there are still some doubtful points in these basins about their stratigraphic division and correlation. Through comprehensively analysing the information of sedimentation, paleontology, key beds and isotopic age determination, this paper thinks that the sediments of the early to late Pliocene were developed in each large-scale basin of this region, whereas the middle to late Pliocene Series were deposited in small basins which subsided later. The positions of the oldest Cenozoic volcanic rocks found in the basins of Longchuanjiang and Lianghe approched respectively to the bottom of Mangbang Formation and Nanlin Formation, but the values of isotopic age only reach 7.19±1.11 Ma and 7.2 Ma which are obviously younger than the values of the Pliocene lower limit(10 Ma). Therefore, the earliest sediments in these basins belong to the early Pliocene in age, and the Mangbang as well as Nanlin Formations, to the Pliocene synchronous sediments.
出处
《云南地质》
1990年第4期321-331,共11页
Yunnan Geology
