In order to study the sedimentary evolution and paleoenvironments change during the early Holocene

a 156 m core (SY01) was obtained from the Sanya basin. The age frame of core SY01 was established based on four AMS

14

C dating results. The paleoenvironmental analysis methods of grain size

loss on ignition (LOI)

grayscale and foraminifera were used to reconstruct the sea level change

sedimentary facies and paleoenvironment evolution in this area. The results show that the SY01 sediments can be divided into five layers: gravel-silty fine sand layer

coarse-silty sand layer

medium-silty sand layer

fine-silty sand layer

and silty sand layer. The foraminifera mainly occurred in the period of 8.1-3.7 cal ka BP

with the highest abundance during 5.2-4.7 cal ka BP. The LOI analysis shows that the contents of organic matter and carbonate were relatively high during 5.2-4.7 cal ka BP

and the grayscale values also reflect the sedimentary environment with a reduction condition. Therefore

the depositional process of the study area can be divided into 5 stages: Inner pluvial faciesLateral pluvial facies-Littoral facies-Estuarine facies-Lagoon facies. The deposition started from ~9 cal ka BP

and the highest sea level occurred at ~5 cal ka BP

and then the Sanya basin became the fresh water environment in the late Holocene.