Abstract
Abstract. The Hunshandake Sandy Lands of northeastern China, currently a semiarid lightly vegetated region, were characterized by perennial lakes and forest stands in the early and middle Holocene. Well-developed dark grassland-type paleosols (mollisols) at the southern edge of the Hunshandake – OSL (optically stimulated luminescence)-dated to between 6.93±0.61 and 4.27±0.38 ka along with lacustrine sands at higher elevations that date to between 5.7±0.3 and 5.2±0.2 ka – and thick gray lacustrine sediments suggest a wetter climate. Between 4.2 and 3.8 ka, the region experienced extreme drying that was exacerbated by lake overflow drainage and sapping that depleted the groundwater table. The region supported a robust population, the Hongshan Culture, but was depopulated post 4.2 ka with migration likely to the Yellow River Valley where the Hongshan introduced their characteristic cultural elements to early Chinese civilization. Evidence for extreme and sudden environmental change in northeastern China, at and following the 4.2 ka BP Event and like that we document in the Hunshandake, is widespread. However, no comprehensive overview of this climatic episode exists. Here, we discuss the relevant events in northeastern China and capture them in a spatially explicit Geographic Information Systems database that can be used to analyze the timing and spatial pattern of climate and environmental change associated with the 4.2 ka BP Event. This approach could serve as a prototype for a global 4.2 ka BP Event database.
Highlights
The Hunshandake Sandy Lands of northeastern China (Fig. 1) are currently characterized by grasslands that overlie semi-stabilized aeolian deposits in its southern and eastern regions and by aeolian sand sheets and dunes in its western region
In this paper we review the environmental change that took place in the Hunshandake bracketing the 4.2 ka BP Event and place it in context relative to other records from northeastern China
We conclude with a discussion of how such a data structure and analysis approach might be used to better understand the 4.2 ka BP Event globally, and we provide the dataset for evaluation and analysis as an online supplement
Summary
The Hunshandake Sandy Lands of northeastern China (Fig. 1) are currently characterized by grasslands that overlie semi-stabilized aeolian deposits in its southern and eastern regions and by aeolian sand sheets and dunes in its western region. While the primary driver appears to be linked to global-scale change occurring at that time, in the Hunshandake it was exacerbated by rapid groundwater drawdown resulting from drainage capture This combined climatic and hydrologic reorganization led to a rapid loss of surface water and a shift from green to sandy conditions over a few hundred years. This environmental shift produced regional depopulation with a significant abandonment of sites across the region lasting until ∼ 3.6 ka (Liu and Feng, 2012; Wagner et al, 2013; Yang et al, 2015). We conclude with a discussion of how such a data structure and analysis approach might be used to better understand the 4.2 ka BP Event globally, and we provide the dataset for evaluation and analysis as an online supplement
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