青海西宁盆地三趾马、副板齿犀化石的发现及意义

首次在青海西宁盆地新近纪河湖相沉积地层中发现了三趾马、副板齿犀牙齿化石,对化石的基本特征和埋藏情况进行了描述,三趾马化石经鉴定为东乡三趾马。结合区域和前人资料认为,本次发现化石的岩石地层应该属于咸水河组或以上层位,时代为晚中新世早期。分析前人孢粉资料认为化石形成时的古植被为森林-草原,古气候环境为亚热带干旱气候环境。这一发现为西宁盆地晚新生代河湖相地层格架的建立,提供了古生物学依据,对西宁盆地中新世地层确立起到时序标尺的作用。为青藏高原东北缘盆地的环境演化、地层划分、时代厘定提供了新的资料,对深入研究青藏高原隆升环境效具有重要意义。同时,也为青藏高原东北缘、华北地区、青藏高原三趾马动物群进行对比研究,提供了基础材料。

Discovery and Significance of Hipparion and Parelasmotherium Fossils in the Xining Basin, Qinghai Province

Hipparion and Parelasmotherium fossils buried in the Neogene sediments in the Xining basin of Qinghai Province have been discovered for the first time. This paper descries in detail characteristics of the fossils and lithostratigraphic characteristics. Primary identification suggests that the Hipparion fossils belong to Hipparion dongxiangense. Combined with the regional geology and previous studies, the authors believe that the sediments belong to the Xianshuihe Formation or overlying strata and are early Late Miocene in age. The primary palynological studies suggest that the Late Miocene vegetation there was composed of mixed evergreen and deciduous broad-leaved forests. The angiosperms were dominant in the study area. The climate was arid in the Xining basin during Late Miocene. The vegetation succession was changing from forest to steppe, suggesting an arid area of the subtropical zone with increasing aridity. This study tried to explore the regional lithostratigraphic characteristics and sedimentological features. By comparing with other mammuthus fossils from the central part and the northeastern edge of the Tibetan Plateau as well as those from North China, this study is of great importance for rebuilding the environmental evolution of Miocene sediments in the Xining basin.