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年代地层单位麻则沟阶是中国上新统的两个阶之一,代表陆相上上新统,1999年由第二届全国地层委员会正式命名,对应于麻则沟期。“麻则沟”一名源自同名岩石地层单位麻则沟组,典型剖面位于山西省榆社县云簇镇赵庄—大马岚。麻则沟阶对应于“国际地层表”中的皮亚琴察阶,其共同的底界定义为古地磁Chron C2An.3n的底,即高斯正极性带的底,绝对年龄为3.6 Ma,这条界线在榆社赵庄剖面位于第6层麻则沟组下部的紫红色黏土层的中部,以张洼沟姬鼠(Apodemus zhangwagouensis)的首现为标志。麻则沟期与欧洲陆生哺乳动物分期的Villa-nyian早期或Villafranchian早期相当,包含1个哺乳动物群单位,即NMU13,可与欧洲的MN16对比。在榆社盆地发现的麻则沟动物群就相当于NMU13。在中国的上新世哺乳动物群中,甘肃灵台的任家沟动物群和雷家河V带动物群、河北阳原泥河湾的稻地动物群、陕西渭南的游河动物群、山西静乐的贺丰动物群、四川德格的汪布顶动物群也相当于NMU13。河北泥河湾的花豹沟剖面是麻则沟阶的辅助层型剖面。
Stratigraphic unit Ma Zegou level is one of the two stages of the Chinese Pliocene, on behalf of the terrestrial Pliocene, formally named by the second session of the National Stratigraphic Commission in 1999, corresponding to Ma ditch period. “Ma ditch” one from the same name rock strata unit Ma ditch group, the typical profile is located in Yushe County, Shanxi Province Yunzhu town Zhao Zhuang - Malaysia Lan. The Maze trench corresponds to the Piacenza in the “International Stratigraphic Table” and its common bottom boundary is defined as the base of the Paleomagnetism Chron C2An.3n, which is the base of the positive Gaussian band with an absolute age of 3.6 Ma , Which is marked by the first occurrence of Apodemus zhangwagouensis in the middle part of the fuchsin clay layer in the lower part of the Mazigou Formation on the 6th floor of the Zhaozhuang section of Yushe. The Marginal ditch period is comparable to the earlier Villa-nyian stratum or Villafranchian terrestrial mammals in Europe, and includes one mammalian herd unit, NMU13, comparable to MN16 in Europe. The Mazegou fauna found in the Yushe Basin is equivalent to the NMU13. Among the Pliocene mammalian herds in China, the Renjiagou fauna and the Lejiahe V belt fauna in Lingtai, Gansu, Henan Province, the Nihewan pelagic river fauna, the Weinan River fauna in Shaanxi, Happy Hefeng fauna, Sichuan Dege’s Wang Bu Ding animal group is also equivalent to NMU13. The Hanbaogou section of Nihewan Bay, Hebei Province, is an ancillary layer profile of the Mazeigou.