Abstract:
In order to reconstruct the changes in (sub)surface water mass since 20.0kaBP, multiproxy investigations, including Ice Rafted Debris (IRD) abundance, AMS
14C dating, foraminiferal abundance, stable oxygen and carbon isotopes of planktonic foraminifera
Neogloboquadrina.
pachyderma (sin.) (
Nps), and (sub)surface temperature derived from
Nps Mg/Ca ratios, have been carried out for two cores collected from the Nordic Seas during the Fifth Chinese National Arctic Expedition. The LGM (20.0~17.5kaBP) is characterized by low subsurface water temperature(~3℃), poor calcium productivity, and enhanced IRD input. During the deglaciation (17.5~11.7 kaBP). Nps-δ
18O and-δ
13C depletions suggested a freshwater event during Heinrich Stadial 1(HS1). Stronger water stratification and north Atlantic water gathering in the subsurface layer caused the increase in subsurface temperature. At the onset of Bølling-Allerød (B/A) event, the subsurface water temperature (4.5℃) indicated an increased advection of Atlantic water. The early Holocene (11.7~8.2kaBP) was characterized by higher subsurface temperature (6.5℃), bioproductivity, and lower IRD input. During the middle Holocene (8.2~4.2kaBP), the gradual increase in bioproductivity during 8.2~5.6kaBP indicated the enhanced ventilation, which led to an increase in nutrient supply. Lower subsurface temperature (~4℃) during the 6.6~5.6kaBP may suggest the decrease in summer solar radiation and weakening of Atlantic water advection. During 5.6~4.2kaBP, the depletion of Nps-δ
13C and δ
18O values indicated poor bioproductivity and subsurface water warming, respectively. During the late Holocene (4.2~0.8kaBP), the Neoglaciation (4.2~3.0kaBP), was characterized by low subsurface temperature and poor bioproductivity. The light values of Nps-δ
18O and the increase in IRD reflected a meltwater event. Since 3kaBP, the continuous increasing of subsurface temperature and bioproductivity may be explained by the increased advection of Atlantic water.