It has been an important research topic in oceanography and climatology to understand the evolution of marine environment in the context of anathroprogenic warming. In the geological past, the Earth has experienced several warming periods (including the early Holocene), which provide natural analogs for future climate. The global climate experienced rapid warming during the early Holocene, accompanied by ice sheet melting and rapid sea level rise, which have significantly impacted sedimentary processes and marine environment in high-latitude marginal seas, including the Bering Sea. The Bering Sea consists of a broad continental shelf, adjacent to the North American continent, and receives material supplies from the Yukon River, Anadyr River and Kuskokwim River. There are still significant gaps in our understanding of how the Bering Sea responds to the early Holocene climate. In this study, high-resolution analysis of major and minor elements in bulk sediments of Core LV63-19-3 retrieved from the northern slope of the Bering Sea, in combination with a well-constrained sedimentary age model to investigate the sedimentary environment changes on the northern Bering Sea slope during the early to middle Holocene (11.7–5.5 ka BP). The results show that the sedimentation rate on the northern continental slope of Bering Sea was as high as 392.9 cm/ka during 11.5–11 ka BP, and decreased rapidly to 17.2 cm/ka after 9.7 ka BP. At 11–10.7 ka BP, a dark laminated sediment layer about of 40 cm thick was found. In the period of high sedimentation rate, the average grain size of sediments was finer, and increased gradually after 9 kaBP. Both major and minor element concentrations indicate that the lithological properties of terrigenous clastic sediments were mainly felsic sediments with a small amount of pyroclastic contributions. The high sediment rate corresponds to the Meltwater Pulse-1B event (11.4–11.1 ka BP) and resulted in a blooming of siliceous productivity on the Bering Sea continental slope. In the study area from 11 ka BP to 10.7 ka BP, the increase in seasonal sea ice coverage inhibited the oxygen supply from the atmosphere to surface water and subsequent transport to the bottom water, while the glacial meltwater and the persistent high productivity in summer and autumn further exacerbated the surface water stratification and ocean interior oxygen consumption on the continental slope of the Bering Sea, both of which together triggered the formation of laminated sediment. After 9 ka BP, the seasonal sea ice activity in the Bering Sea increased gradually, but the mass accumulation rate of terrigenous detrital materials decreased, indicateing a decrease in the supply of terrigenous materials to the study area along with sea level rise. We suggest that the rapid shift in early Holocene sedimentary environment on the northern Bering Sea continental slope is the result of a combination of sea level, Meltwater Pulse 1B event and seasonal sea ice activity, which is actually controlled by high-latitude solar insolation, North American ice sheet melting, and global climate.
| 科 Family | 属数 Number of genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) | 属 Genus | 种数 Number of species | 占总种数比例 Percentage of total species (%) |
|---|---|---|---|---|---|---|
| 鹅膏菌科Amanitaceae | 2 | 11 | 5.26 | 鹅膏菌属 Amanita | 10 | 4.78 |
| 小菇科 Mycenaceae | 2 | 12 | 5.74 | 丝盖伞属 Inocybe | 5 | 2.39 |
| 多孔菌科 Polyporaceae | 8 | 14 | 6.70 | 蜡蘑属 Laccaria | 5 | 2.39 |
| 红菇科 Russulaceae | 3 | 23 | 11.00 | 小皮伞属 Marasmius | 6 | 2.87 |
| 小菇属 Mycena | 11 | 5.26 | ||||
| 光柄菇属 Pluteus | 5 | 2.39 | ||||
| 红菇属 Russula | 17 | 8.13 | ||||
| 栓菌属 Trametes | 5 | 2.39 |