As the largest inland basin in the northeastern Tibetan Plateau, Qaidam Basin has traditionally been thought of as the key region to study the Cenozoic climatic changes in the plateau; however, the information from a palaeobotanic respect is still lacking because of the paucity of the fossil plants. Fossil fruits and foliage of Ailanthus (Simaroubaceae) are reported from the Oligocene Shangganchaigou Formation in the northwestern Qaidam Basin, Qinghai Province, China. All the characters suggest that the fossil materials should be assigned to A. confucii, which is one widely distributed fossil species in the Cenozoic, regarded as the analogue of extant A. altissima. Current materials represent the first fossil record of Simaroubaceae in the northern Tibetan Plateau. Based on the climate requirements of the living A. altissima, the ranges of mean annual temperature (MAT) and mean annual precipitation (MAP) reflected by current fossils from Qaidamare 6.9–17.0°C, and 376–1,383 mm, respectively, compared with the current climate at the fossil site with MAT of −1.03°C and MAP of 60.5 mm. The results indicate that the climate conditions of the fossil site during the Early Oligocene were much warmer and more humid than that of the current. We hereby suggest the warm and moist air could approach the northwestern Qaidam and to accommodate the ecological environment in Early Oligocene.

中文翻译：

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青藏高原北部柴达木盆地西北部的全新世臭椿及其影响

柴达木盆地是青藏高原东北部最大的内陆盆地，传统上一直被认为是研究高原新生代气候变化的关键地区。然而，由于化石植物的匮乏，仍然缺少来自古植物学方面的信息。据报道，来自青海省柴达木盆地西北部的渐新世上甘柴沟组的臭椿和化石果实。所有的角色表明，化石材料应该被分配到一个。孔子是新生代广泛分布的一种化石，被认为是现存A. altissima的类似物。目前的材料是青藏高原北部Simaroubaceae的第一个化石记录。根据生活中的A. altissima的气候要求，来自柴达木尔的当前化石分别反映的年平均温度（MAT）和年平均降水量（MAP）的范围分别为6.9-17.0°C和376-1,383 mm，化石场目前的气候，MAT为-1.03°C，MAP为60.5 mm。结果表明，渐新世早期的化石场的气候条件比当前的气候条件温暖得多。我们在此建议，温暖潮湿的空气可以到达柴达木西北部，并适应渐新世早期的生态环境。