中文摘要：

黄河源区气候和环境演化过程和机制的系统研究对青藏高原东北部冻土环境对气候变化的响应非常重要。在青藏高原东北部黄河源区勒那曲流域汤岔玛盆地南缘，根据万隆哇玛河泥炭剖面（WLR：34°39′4．71″N，97°20′0．90″E；4400ma．s．L．）的磁化率、烧失量、地球化学元素氧化物及其比率等参数，重建了6．1cal．ka B．P．以来黄河源区的气候演化过程。结果表明，黄河源区的气候演化过程可以分为4个阶段：6．1～2．1cal．ka B．P．，气候暖湿，其中，又以5．4cal．ka B．P．为界分为2个亚阶段，6．1～5．4cal．kaB．P．气候偏暖湿，而5．4～2．1 cal．ka B．P．气候偏冷干；2．1～1．5cal．ka B．P．，气候凉湿；1．5～0．8cal．ka B．P．，气候相对暖湿；0．8cal．ka B．P．以来气候趋于暖湿。6．1cal．ka B．P．以来，黄河源区气候变化过程具有高度的不稳定性及百年一千年尺度振荡的特点，在6．1～5．8cal．ka B．P．、5．4～3．9cal．ka B．P．、3．0～2．1cal．ka B．P．、1．9—1．5cal．ka B．P．、1．3—1．1cal．ka B．P．和0．8～0．3cal．ka B．P．等表现出明显的6次冷事件，这与青藏高原泥炭和湖相沉积、冰芯、北半球低纬度泥炭沉积乃至高纬度深海沉积等记录的冷事件具有明显对应关系。以上结果表明，中晚全新世以来黄河源区的气候变化与全球气候变化具有一致性。

英文摘要：

The source area of the Yellow River （SAYR） is located in the transition zone between the Asian monsoon zone, the northwestern arid zone, and the alpine and cold zone on the northeastern Qinghai-Tibet Plateau （QTP）. It is located in the catchment area above Duoshixia, approximately between 33°56′-35°31′N and 95°55′- 98°41′E, with an area of about 2.5× 10^4km2. Its fragile ecosystems and the simple structure of its natural environment are sensitive to climate change, making it an ideal region for global climate change research. Systematic study of climatic and environmental evolution processes and mechanisms in the SAYR is of vital importance for the exploration of response of permafrost environment to climatic changes on the northeastern QTP. A peat profile WLR （34°39′4. 71″N, 97°20′0. 90″E; 4400m a.s.l., 480cm in length） was dig in October, 2014, which was 5km away from the Wanlongwama Lake, located in the south of the Tangchama Basin in the Lena River Basin in the south-central SAYR on the northeastern QTP. The maximum seasonal thaw depth of the active layer was about 80cm, and the average soil water content was 240% at depths of 80-480cm in the permafrost layer. 78 soil samples were collected from the bottom to the top of the profile at every 10cm between 480-300cm and at every 5cm between 300-0cm. In this study, the climatic evolution since 6. lcal.ka B.P. in the SAYR was reconstructed using the records of magnetic susceptibility, loss on ignition （LOI） , and geochemical elements of the WLR profile. The results showed that the climatic evolution since 6. lcal.ka B.P. in the SAYR could be divided into four stages. The first stage was warm and wet during the period of 6. 1-2. lcal.ka B.P., and could be further divided into two sub-stages ： from 6. lcal.ka B.P. to 5.4cal.ka B.P. the climate was warm and humid and from 5.4cal.ka B.P. to 2. lcal.ka B.P. it was cold and dry. In the second period, from 2. lcal.ka B.P. to 1.5cal.ka B.P., the climate was cold and dry; it was rel