The revised route which we travelled. Anna and I only got as far as about 150km north of Jiuquan before we were made to turn around and get the train back to Lanzhou.
Loess in the Loess Plateau potentially comes from many source regions, the precise locations of which are highly debated.
In this first part of the trip we visited the Qilian Shan Mountains and their alluvial fans. Fluvial activity and erosional processes in mountain belts are involved in the formation of silt, accumulating in large fans at the base of mountains, one potential source for the loess on the Loess Plateau.
We also visited the Badain Jaran desert as desert processes such as the interaction of sand grains with each other and with rock outcrops are also involved in the formation of silt.
The silt produced in the deserts or mountain fans can then be deflated by the wind and deposited as loess on the plateau.
It is also possible that the silt and loess produced by mountain processes have been transported to deserts in the North and West of China, such as the Badain Jaran, where silt sediment is stored over long periods before subsequent transport to the Loess Plateau.
In our sampling we are aiming to obtain mainly sand and silt sized grains from these potential source regions. We will then conduct various geochemical analyses on the samples back in the laboratory, in collaboration with Lu Huayu’s group back in Nanjing University.
Sand and silt are the appropriate sizes needed for heavy mineral analysis and zircon U-Pb dating, which are two of the main methods used in this project.
Sandy sediment of a dried up alluvial fan.
Sample of an unsorted modern river.
Example of a river terrace where structures can be seen of larger boulders and pebbles at the base, and finer material towards the top.
Sediment sample of a modern river terrace all bagged and labelled up.
Silty sediment of modern Black River.
Sand samples at Alxa Geopark.