Quaternary paleolake development in the Fen River basin, North China

The Taiyuan Graben and the Linfen Graben are two fault-controlled grabens in the Fen River basin, north China. Broad paleolakes periodically occupied the two grabens during the Pleistocene. This paper discusses how neotectonic activities and paleoclimate changes may have influenced the development of the paleolakes in the two grabens during the middle to late Quaternary, based on the lacustrine landforms and sediments. The distribution of lake terraces and their correlation with loess/paleosol series indicate that three paleolake regressions with vertical drops of about 40-60 m occurred in the two grabens at about 0.76 Ma B.P., 0.55 Ma B.P. and 0.13 Ma B.P. Analysis of the factors controlling paleolake development suggests that rapid tectonic uplift may be the main cause of the three paleolake regressions. Changes in the facies of the lacustrine sediment also suggest that, when tectonic movements were relatively weak, paleoclimate became the main factor causing 2-3 m fluctuations of the paleolake level.