山东章丘黄土粒度指示的粉尘堆积过程及古气候意义

doi:10.11821/dlxb202105009

Abstract

Abstract:

The accumulation processes of loess in Shandong Province record atmospheric circulation changes in eastern China, which is significant in revealing the varied characteristics of East Asian monsoons and palaeoenvironmental change. In this study, the parameterized end-member modelling analysis of grain-size distributions is used to discuss the sedimentary characteristics, transport dynamics and environmental significance for a loess section in Zhangqiu, Shandong Province. The results indicated that: (1) The optically stimulated luminescence (OSL) ages of the Zhangqiu section ranged from 0.26 to 42.24 ka, suggesting that sediments have mostly deposited since the late Pleistocene. (2) The grain size components of the sediments in this section were divided into five end members: EM1 represents the mixed clay component of pedogenesis and transported sediment, EM2 represents the fine silt component transported by the high-altitude westerly wind over long distance, EM3 represents material that settles as floating dust, EM4 is the main material source of the profile, which represents the silt component transported by low-altitude suspension under local wind systems, and EM5 represents short-distance suspended materials under dust storm conditions. Change in the EM5 component is a good indicator of winter monsoon intensity change, and has recorded all climate fluctuation events since the late Pleistocene. (3) According to the climatic proxies such as the grain-size end-member content, low frequency magnetic susceptibility (χ_lf) and chromaticity (a^*), combined with the results of OSL, this effectively indicated the stage change and differences of the sedimentary environment in the Zhangqiu section since the late Pleistocene and reflected the regional response to global climate change.

Key words: loess, end-member modelling analysis of grain-size distributions, dust accumulation, environmental evolution, Shandong Province

KONG Fanbiao, CHEN Haitao, XU Shujian, MIAO Xiaodong. Dust accumulation processes and palaeoenvironmental significance of loess indicated by grain size in Zhangqiu, Shandong Province[J].Acta Geographica Sinica, 2021, 76(5): 1163-1176.

Figures/Tables 9

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References 53

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实验编号	野外编号	埋深 (cm)	U (Bq/kg)	Th (Bq/kg)	K (Bq/kg)	实测含水量(%)	环境剂量率(Gy/ka)	等效剂量 (Gy)	年龄 (ka)
16-OSL-523	HY01	100	28.1±1.9	48.5±0.5	659±10	11±5	3.42±0.14	0.90±0.04	0.264±0.017
16-OSL-524	HY02	250	28.7±2.6	46.0±0.5	656±10	18±5	3.13±0.12	49.1±1.1	15.7±0.7
16-OSL-525	HY03	370	26.5±1.7	45.4±0.5	654±10	12±5	3.27±0.13	67±3	20.4±1.4
16-OSL-526	HY04	470	27.4±2.6	45.0±0.5	653±10	17±5	3.10±0.12	73±3	23.6±1.4
16-OSL-521	HY05	717	31.3±2.1	48.3±0.5	602±10	10±5	3.22±0.13	101±5	32.0±2.0
16-OSL-522	HY06	1260	31.1±1.6	47.2±0.5	617±10	9±5	3.23±0.14	126±5	39.0±2.0

剖面	平均粒径(Mz/um)	分选系数	偏度(Sk)	峰度(Kg)	粘土(%)	粉砂(%)	砂(%)
EM1	1.06	1.66	0.64	3.25	98.93	1.07	0.00
EM2	6.01	2.08	0.24	2.76	32.38	67.53	0.08
EM3	12.66	2.04	-0.27	2.89	6.89	92.71	0.40
EM4	29.84	1.67	-0.52	3.29	0.06	95.95	3.99
EM5	56.20	1.44	-0.73	3.82	0.00	63.86	36.14

	EM1	EM2	EM3	EM4	EM5	Md
EM1	1
EM2	0.349^***	1
EM3	-0.318^***	-0.246^***	1
EM4	0.011	-0.424^***	-0.679^***	1
EM5	-0.152	-0.330^***	-0.641^***	0.550^***	1
Md	-0.094	-0.610^***	-0.499^***	0.730^***	0.805^***	1

Dust accumulation processes and palaeoenvironmental significance of loess indicated by grain size in Zhangqiu, Shandong Province

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