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马衔山是目前黄土高原地区唯一证实有多年冻土发育的山脉.残存的多年冻土被誉为黄土高原地区多年冻土的“活化石”.近20a来马衔山多年冻土发生了明显的退化,目前仅在小湖滩有岛状多年冻土残存,属于典型的高温多年冻土,1990年代初在其它区域发现的零星多年冻土已经基本消失.马衔山岛状多年冻土地温从10～16m的-0.2℃向上和向下升高,地温梯度±0.01℃·m-1左右,相比1990年代初,多年冻土地温上升了0.1～0.2℃,年升温率为0.006～0.012℃·a-1,小于青藏高原高温多年冻土平均升温速率.马衔山多年冻土最大厚度约40m,正在发生着上引式和下引式退化,而岛状冻土边缘区域侧引式退化起主导作用.马衔山多年冻土发育有丰富的地下分凝冰,根据地下冰发育特征和埋藏有机质层14C测试资料分析,马衔山多年冻土在新冰期形成后发生过多次地表重复堆积,共生共长作用是地下冰形成的重要原因.丰富的地下冰和厚层有机质层的保护作用,以及区域寒冷的微气候环境,应该是马衔山多年冻土残存的主要原因.
Ma Mountain is the only mountain range in the Loess Plateau with proven permafrost development and the remaining permafrost is known as the “living fossil” of permafrost on the Loess Plateau. Obviously degraded. At present, only island-shaped permafrost remains on the small beach, which belongs to the typical high temperature permafrost. The sporadic permafrost found in other areas in the early 1990s basically disappeared. The geotemperature increased from -0.2 ℃ at 10 ~ 16m upwards and downwards, and the geothermal gradient was about ± 0.01 ℃ · m-1. Compared with the early 1990’s, the ground temperature in permafrost increased by 0.1 ~ 0.2 ℃ and the annual warming rate was 0.006 ~ 0.012 ℃ · a-1, which is less than the average temperature of permafrost at high temperature in the Qinghai-Tibet Plateau. The maximum thickness of the Maoding Shan permafrost is about 40m, and the upper and lower degeneration are taking place. Degeneration plays a leading role.Maoding Mountain permafrost is rich in underground sub-condensate ice, according to the development characteristics of underground ice and buried organic matter layer 14C test data analysis, the Ma Jingshan permafrost in the formation of the new ice age occurred many times Repeated accumulation of the surface, the symbiotic total length is underground The important reasons for the formation of the rich and protection of underground ice layer thick layer of organic matter, as well as regional cold microclimate, should be the main reason Maxianshan remaining permafrost.