Abstract:
Objective The Songnen Plain, located at the edge of the East Asian Summer Monsoon (EASM), is an important region for studying the variability of the hydrological cycle recorded by Pleistocene lacustrine sediments on orbital timescales. Investigating these variations helps to understand the evolution of the water cycle and ancient lake productivity in the lacustrine records of Northeast China.
Methods This study applied Electron Spin Resonance (ESR) dating to samples from borehole BQZK05, obtained from the Ground Substrate Survey in the Songnen Plain, to acquire sedimentary records from approximately 1025 ka. The ESR age data were processed using the Bayesian age−depth model, and spectral analysis was performed on Total Organic Carbon (TOC) and Gamma Ray (GR) data to identify periodic signals.
Results The results from the ESR Bayesian age−depth model show that TOC exhibits significant cycles of approximately 173 kyr and 100 kyr. The Gamma Ray (GR) data from 870～40 ka reveal a dominant ~173 kyr cycle. The ~100 kyr cycle observed in TOC suggests that high−latitude ice volume significantly influences vegetation content and lake biological productivity in the Songnen Plain.
Conclusions Changes in high−latitude ice volume and low−latitude solar radiation have jointly driven climate change in the Songnen Plain during the Middle to Late Pleistocene. The prominent ~173 kyr cycle observed in both TOC and GR data sequences indicates that this cycle played an important role in organic carbon burial.
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