OSL dating of coastal sand dunes in southeastern China provides new insights into the relationship between aeolian activity and eustatic sea-level fluctuations

Abstract

The southeastern coastal region of China has coastal sand dunes, which are usually called paleo-sand dunes or “Old Red Sandstone”. The ages and geological implications of these coastal dunes have been studied for tens of years but are still controversial. In this paper, we used optically stimulated luminescence (OSL) dating to establish the chronology of the paleo-aeolian reddish sand dunes from two representative sites in the coastal region of SE China. Our results indicate that the sand dunes were mainly accumulated in three periods, including 9–6 ka (broadly corresponding to marine isotope stage (MIS) 1), 50–26 ka (MIS 3), and 110–74 ka (MIS 5). Based on the comparison between the regional aeolian dune records and the global sea-level fluctuations, we concluded that the reddish sand dunes were associated with the aeolian processes during interglacials and interstadials when sea-level were relatively higher compared with glacial maxima. We proposed a conceptual model to interpret the formation of the coastal sand dunes. We suggest that coastal dunes that formed during the glacial maxima could not be preserved in highstands above the present sea-level due to the lower altitude of sand dunes and the erosion by water waves during the subsequent marine transgression. Therefore, only aeolian sand dunes accumulated in higher altitudes during sea-level rise were preserved as in the coastal region of SE China.