第七届青年地学论坛

As an important geomorphologic element of the coastal areas, lagoons receive relatively less attention than estuaries and deltas in the NW Pacific. In this study, based on multiple proxies of δ¹³C, pollen and diatoms, we attempt to understand the Holocene sedimentary environment of the Songji lagoon, South Korea, and the possible mechanism for its response to global or regional sea level and climate change. The sedimentary environment was phased differently in different periods: it was an estuary, a lagoon in the estuary area, an intermediate environment between fresh water and brackish water, and a brackish lagoon environment in early Holocene -6669 cal yr BP, 6669-6325 cal yr BP, 6325-4492 cal yr BP and 4492-1340 cal yr BP, respectively. Afterward, abundant freshwater entered the lagoon from the stream. The changes were triggered by sea level and climate changes. Based on the fluctuating sedimentary environment, we can infer that the sea level increased from 4.5 to 2.2 cal kyr BP, and decreased from 2.2 to 0.8 cal kyr BP. The sedimentary environmental change is also closely connected with El Niño/La Niña-like activity, especially in the periods 6.7-6.3 cal kyr BP, 4.5-3.6 cal kyr BP and 3.0–2.0 cal kyr BP.

Sedimentary environment,Pollen,δ13C,Diatom,Climate change