Quantitative reconstruction of consecutive paleolake-level fluctuations by the groundwater recharged lake in the desert hinterland: A case study in the Badain Jaran Desert, Northwestern China

Abstract

Quantitative reconstruction of consecutive paleolake-level fluctuations may help reconstruct lake evolution during the Holocene. However, the reconstruction of a groundwater recharged lake in a desert hinterland is challenging. In this study, 23 samples of lake bottom sediments were obtained from eight groundwater recharged lakes in the hinterland of the Badian Jaran Desert in northwest China to establish models between the grain size component and lake level. Our results showed that the four grain size components of the sediments could be separated using the Weibull function. The first two fine grain components (W1 and W2) were deposited in the atmospheric dust. The two coarser components (W3 and W4) could be interpreted as sediments transported by wind from the surrounding sand dunes, while W3 was subsequently redistributed by lake waves. Changes in the lake water depth could be expressed by the W1 and W2 component contents, as well as the modal size of W3. Using the above models, unmixing grain size components of the lake sediment obtained from the ZZH section located in a seasonal lake (Zhunzhahan Jaran Lake) in the desert hinterland were used to quantitatively reconstruct the lake-level fluctuations during the Holocene. The lake level frequently fluctuated between 3.82 and 9.21 m during 10.6–8.6 cal kyr BP, slightly fluctuated between 3.41 and 5.26 m during 8.6–4.7 cal kyr BP, and markedly declined from 6.09 m to 4.46 m during 4.7–3.5 cal kyr BP. Lake-level changes in the hinterland of the Badian Jaran Desert did not correspond to the effective moisture changes during the early Holocene. Instead, the rise in lake level during the early Holocene would have resulted from the input of groundwater from the meltwater in the mountains of the recharge area. The data reveal new methods for quantitatively reconstructing consecutive paleolake-level fluctuations by groundwater recharged lakes in the desert hinterland.