Acta Geographica Sinica ›› 2019, Vol. 74 ›› Issue (11): 2371-2384.doi: 10.11821/dlxb201911013

• Climate Change and Ecological Environment • Previous Articles     Next Articles

OSL dating of the pedo-stratigraphic sequence and the prehistoric flash floods and mudflows over the Lajia Ruins of Qinghai Province

CUAN Yuda1,HUANG Chunchang1(),PANG Jiangli1,ZHOU Yali1,ZHANG Yuzhu2,GUO Yongqiang3,WANG Haiyan1,ZHAO Qiqi1   

  1. 1. School of Geography and Tourism, Shaanxi Normal University, Xi'an 710062, China
    2. College of Urban and Environmental Science, Northwest University, Xi'an 710127, China
    3. Institute of Mountain Hazards and Environment, Chinese Academy of Sciences, Chengdu 610041, China
  • Received:2018-12-20 Revised:2019-07-01 Online:2019-11-25 Published:2019-11-01
  • Contact: HUANG Chunchang
  • Supported by:
    National Natural Science Foundation of China(41771110);National Natural Science Foundation of China(41801060);National Key R&D Program of China(2017YFC1502501);Special Research Project of Education Department of Shaanxi Provincial Government(17JK0770)


Environmental change and human-land relationship evolution over the Qinghai-Tibet Plateau are the frontiers of global change science. The Lajia Ruins in the Guanting Basin situated in the northeast margin of the Qinghai-Tibet Plateau has preserved many records of the Holocene environmental change, human activities, complex surface process evolution and abrupt catastrophic events. Therefore, the Lajia Ruins has received extensive attention from scientists from different fields, and has also attracted attention from world media. It is still quite controversial about the causation and age of the prehistoric catastrophe. After extensive field works over the years, a complete pedo-stratigraphy profile of soil and sediments has been found in the northern part of the Lajia Ruins. On the basis of field pedo-sedimentological observation and description, as well as physic-chemical analysis and OSL dating on the soil and sediment samples taken from the profile, a pedo-stratigraphic sequence and related chronology have been established in the Lajia Ruins. The results show that the profile has been developed from 12000 a BP. The pedo-stratigraphic sequence includes the Late Pleistocene Malan loess (L1-1), Holocene transitional loess (Lt), the Middle Holocene palaeosol (S0), the recent loess (L0) and the modern topsoil (MS). The Middle Holocene palaeosol (S0) is separated by three layers of red clay, which were deposited by large flash floods and mudflows during 3960-3650 a BP. These catastrophic events occurred at about 3850 a BP, 3800 a BP and 3600 a BP, respectively. The first mudflow event overflowed the gully channel and spread over a large area on the Yellow River terrace, and covered the eastern part of the large settlement of the Qijia Culture at 3850 a BP. All these facts indicate that the Lajia Ruins was destroyed by earthquakes in combination with large flash floods and mudflows coming along the gullies that originated from the hills of the Tertiary Red Formation. These results are very important in understanding environmental change and human-land relationship evolution, formation of the settlement of the Qijia Culture, pre-historical human impact and causation of catastrophe in the Guanting Basin.

Key words: Lajia Ruins, prehistoric catastrophe, mudflow event, stratigraphic sequence, OSL dating