青藏高原尼玛盆地东部古近系昆虫化石的发现及其对古气候的指示

藏北尼玛盆地自白垩纪以来沉积了巨厚的陆相碎屑岩夹灰岩地层，由于缺乏生物化石证据，其地层时代一直存在较大的争议。最近，在尼玛盆地东部赛布错一带的细碎屑岩夹灰岩地层中发现大量的昆虫、鱼类和植物化石。昆虫化石主要为伦坡拉大黾蝽Aquarius lunpolaensis，与伦坡拉盆地达玉地区和尼玛盆地西部江弄淌噶地区报道的种属形态特征基本一致，显示该套地层为晚渐新世丁青湖组沉积，而不是竟柱山组或牛堡组。另外，伦坡拉大黾蝽主要生活在温暖湿润的低海拔地区，结合近年在青藏高原中部伦坡拉盆地和尼玛盆地晚渐新世地层中发现的热带-亚热带鱼类和大植物化石组合，指示青藏高原腹地在晚渐新世为温暖湿润的低地环境，而不是过去认为的高寒气候。

The discovery of Paleogene insect fossils in eastern Nima Basin,Tibet, and its implication for paleoclimate

Since the Cretaceous period, thick terrigenous clastic rocks interbedded with limestone strata have been deposited in the Nima Basin, northern Tibet, but the deposition age is still debatable due to the lack of fossil evidence.Recently, a lot of insect, fish and plant fossils were discovered from the fine clastic rocks interbedded with limestone strata in the Saibu Co area in the east of the Nima Basin.The insect fossils mainly consist of Aquarius lunpolaensis, which is consistent with the morphological characteristics of the species reported in the Dayu area in the Lunpola Basin and the Jiangnongtangga area in the west of Nima Basin, indicating that this set of strata was Late Oligocene Dingqinghu Formation rather than the Jingzhushan Formation or Niubao Formation.In addition, Aquarius lunpolaensis mainly existed in warm and humid environment at low elevation area and, in combination with tropical to subtropical fish and plant fossil assemblage in the Late Oligocene strata in the Lunpola and Nima basins of central Tibet found in recent years, the authors argue for a warm and humid lowlands environment in the Late Oligocene period in the central Tibet rather than high and cold climate as used to be considered.