Holocene environmental evolution history based on sporopollenin and micropaleontological reconstruction of KY-01 in the Yellow River Delta

Abstract

The Yellow River Delta adjacent to the Bohai Sea is located in the monsoon region of northern China, which is sensitive to global climate change. The core data of KY-01 borehole in the Yellow River Delta and the published records were used to reconstruct the climate environment. Based on the analysis of carbonate content, magnetic susceptibility, Ostracoda, foraminifera, sporopollenin and AMS 14C dating on the KY-01 borehole sediment core, the evolution of both the climate and sedimentary environment has been discussed. The results show that: 7656–4145 cal.aBP, seawater moved toward the land surface and the climate was generally warm and humid, when there were small-scale extreme climate fluctuations; 4145–2544 cal.aBP, transgression and recession occurred, the climate changed from warm-wet to dry-cold and there were small-scale extreme climatic events; and 2544 cal.aBP–1855 AD, the sea level was relatively low, transgression and retreat alternately occurred, the climate was drier and colder than the previous stage and the warming and cooling alternated. During the middle Holocene, cold-dry events occurred between 5737–5422 and 4451–4081 cal.aBP, which is consistent with both Chinese and worldwide climate records.

Centralization or decentralization? A spatial analysis of archaeological sites in northern China during the 4.2 ka BP event

“…The shifting channels of the lower reaches of the Yellow River have been of significant threat to the livelihood and civilizational development of ancient Chinese. Meanwhile, the coastline of North China was much closer to the inland area four millennia ago due to the megathermal effect (Wang K et al, 2022; also see the map with ancient coastline/river courses given as follows), that is why large amounts of sites are distributed in the south of the ancient Jishui River and encircle the Shandong Hills with higher altitude, where the Longshan culture flourished throughout the late Neolithic (Han et al, 2021;. The termination of such a mild climate at circa 4.2 ka BP was preserved by multi-proxy geological records via pollen, loess-paleosol, marine sediment, etc., all of which indicate an abrupt cooling and aridification trend that incurs widespread environmental deterioration/degradation in both ends of northern China (An et al, 2005;Chen and Wang, 2012;Han et al, 2021;Wang K et al, 2022).…”