The Late Pleistocene Paleoclimate Evolution Of The SG01 Core In The East Of Beijing Plain

At present,the research on paleoclimate and paleoenvironmental restoration has become a hot topic of global climate change.In the past few decades,researchers have made a lot of achievements on paleoclimate change with different geological records and different substitution indexes.These achievements provide a basis for understanding the changing rule and mechanisms of global climate change.In this paper,magnetic stratigraphy,sporopollen,environmental magnetism and granularity of the SG01 core sediment sediment in the east of the Beijing Plain were studied to establish the age frame,and to divide the sedimentary facies and to reveal the evolution of the paleoenvironment.?1?According to stepwise demagnetization results,¹⁴C results and previous researches,established SG01's magnet magnetic polarity column.The B/M boundary is at the depth of 190.6m for SG01 core.The Gothenburg event subchron is at the depth of 9.9¹2.5m for SG01 core.The Lashang event subchron is at the depth of27.5³6.6m for SG01 core.The Black event subchron is at the depth of 70.4⁸1.2m for SG01 core.The Bottom of the Holocene is defined at the depth of 10.6m for SG01core,and the Bottom of the upper Pleistocene is defined the depth of at 83.8m for SG01 core,and the Bottom of the middle Pleistocene is defined the depth of at190.6m for SG01 core.?2?The age of the depth of 51⁷3m for SG01 core was 61.1¹09.8ka.The average sedimentation rate of the depth of 51⁷0.4m was 0.0498 cm/a,and the average sedimentation rate of the depth of 70.4⁷3m was 0.108 cm/a.?3?The granularity of columnar sediments with a depth of 51⁷3m in SG01 is generally fine,with poor sorting.The frequency distribution curve is mostly single-peak,the peak variation range is large,and the double-peak and multi-peak state curves are less,indicating the single sediment composition.The probabilistic cumulative curve is mainly represented by two-stages,indicating that the whole is a low-energy depositional environment and is formed under stable conditions.Based on these,the sedimentary environment characteristics of SG01 core depth 51⁷3m were obtained:lake delta,shorelake subfacies,shallow lake and deep lake.?4?The magnetic characteristics of the SG01 drilling depth 51⁷3m are very obvious.According to the variation of magnetic parameters and the change of granularity,it can be seen that the climate of the Late Pleistocene in the east of the Beijing Plain experienced a process of moist and cold-wet and warm-drying and cooling.