万琳琪^1,2,,
朱丽东^1,,,
彭淑贞^2,3,,,
丁敏²,
赵秋月²,
张伟^2,3,
郝青振^3,4,5,6
1. 浙江师范大学地理与环境科学学院, 浙江 金华 321004
2. 泰山学院旅游学院, 山东 泰安 271000
3. 中国科学院地质与地球物理研究所, 中国科学院新生代地质与环境重点实验室, 北京 100029
4. 中国科学院生物演化与环境卓越创新中心, 北京 100044
5. 中国科学院大学地球与行星科学学院, 北京 100049
6. 中国科学院地球科学研究院, 北京 100029

基金项目: 国家自然科学基金项目(批准号:41888101、41472313、41402319和41877442)资助


详细信息

作者简介: 万琳琪, 女, 26岁, 硕士研究生, 自然地理学专业, E-mail:wanlinqibb@163.com

通讯作者: 朱丽东, E-mail:zhulidong@zjnu.cn; 彭淑贞, E-mail:pengshuzhen@tsu.edu.cn

中图分类号: P595

收稿日期:2020-04-18
修回日期:2020-07-20
刊出日期:2020-11-30

Clay mineral composition of loess deposits and it's paleoenvironmental significance in the northern piedmont of the Central Shandong Mountainous Region

Wan Linqi^1,2,,
Zhu Lidong^1,,,
Peng Shuzhen^2,3,,,
Ding Min²,
Zhao Qiuyue²,
Zhang Wei^2,3,
Hao Qingzhen^3,4,5,6
1. College of Geography and Environmental Science, Zhejiang Normal University, Jinhua 321004, Zhejiang
2. School of Tourism, Taishan University, Tai'an 271000, Shandong
3. Key Laboratory of Cenozoic Geology and Environment, Institute of Geology and Geophysics, Chinese Academy of Sciences, Beijing 100029
4. CAS Center for Excellence in Life and Paleoenvironment, Beijing 100044
5. College of Earth and Planetary Sciences, University of Chinese Academy of Sciences, Beijing 100049
6. Innovation Academy for Earth Sciences, Chinese Academy of Sciences, Beijing 100029


More Information

Corresponding authors: Zhu Lidong,E-mail:zhulidong@zjnu.cn ; Peng Shuzhen,E-mail:pengshuzhen@tsu.edu.cn

MSC: P595

--> Received Date: 18 April 2020
Revised Date: 20 July 2020
Publish Date: 30 November 2020


摘要
摘要:鲁中山地北麓的黄土沉积是我国东部平原区第四纪冰期-间冰期古环境变化的重要记录。目前，对这套沉积经历的风化成壤过程还没有开展系统的研究，限制了轨道尺度古环境变化信息的挖掘。本文采用X射线衍射分析方法，对鲁中山地北麓黑山剖面末次间冰期以来代表性的黄土L₁和古土壤S₁样品进行了粘土矿物测试分析。结果表明，黑山黄土沉积的粘土矿物组成以伊利石和蛭石（含层间羟基矿物，简称HIM）为主，二者含量在70.9%~82.2%之间，而高岭石、绿泥石和蒙脱石含量相对较少；与冰期黄土L₁相比，间冰期古土壤S₁含有较高的蛭石（+HIM）和高岭石，而伊利石、绿泥石和蒙脱石的含量相对较低，并且伊利石结晶度KI值和绿泥石风化指数（0.47/0.71 nm）显著增高。粘土矿物组合以及伊利石和绿泥石的化学风化特征表明古土壤经历了中等风化成壤作用，指示了暖温带湿润-半湿润的气候环境，夏季风显著增强。末次冰期黄土L₁中含有较多碎屑成因的蛭石（+HIM），与已有黄土高原末次冰期黄土研究结果对比分析后，排除了鲁中山地北麓黄土与黄土高原黄土一样主要来自西北内陆荒漠区的可能，这进一步支持了鲁中山地北麓黄土主要来源于近源的华北平原各类沉积物的结论。
关键词: 粘土矿物/
黄土-古土壤/
鲁中山地/
风化成壤/
物源

Abstract:The loess deposits in the northern piedmont of the Central Shandong Mountains(CSM) region are significant records of Quaternary paleoenvironmental changes in the eastern plains of China. At present, there is no systematic research on the weathering and soil formation process experienced by this set of sediments, which limits the interpretation of paleoenvironmental information. In this paper, the Heishan(36°10.05'N, 116°20.63'E) section, a typical eolian loess section in the northern piedmont of the CSM, was investigated. Annual temperature and precipitation are typically 14.4℃ and 631.0 mm in this region, respectively. The section has a thickness of 12.3 m, with yellow plough horizon(0~0.8 m), greyish black Holocene soil(S₀:0.8~2.9 m), Malan loess(L₁:2.9~7.5 m) and the last interglacial palaeosol(S₁:7.5~12.3 m). The Optically Stimulated Luminescence(OSL) dating results indicate that the top and bottom ages of L₁ are 10.9±0.6 ka and 65.0±2.2 ka, respectively(Zhao et al., 2019, 2020). Clay minerals were measured using the X-ray diffraction(XRD) on oriented mounts of clay-sized particles(< 2 μm). In this section, 5 and 7 samples were selected from the glacial loess(L₁) and the last interglacial soils(S₁), respectively. All samples for clay minerals analysis were disaggregated in deionized water and treated with 10% H₂O₂ and 1 mol/L HAC to remove organic materials and carbonate, respectively. XRD Analysis was carried out using a PANalytical X'Pert PRO X-ray Diffractometer with CuKα radiation, operating at 40 kV, 40 mA. Identification of clay minerals was made mainly according to the position of the (001) series of basal reflections on the XRD diagrams(Moore and Reynolds, 1989). Illite crystallinity(Kübler index, KI) was obtained from the full width half maximum of the 1.0 nm peak(Δ°2θ).
Lower values indicate higher crystallinity, characteristic of weak hydrolysis under dry and cold climate conditions in continental environments. Chlorite ratio, an index for charactering the weathering of chlorite, was calculated as the ratio of the areas of the 0.47 nm and 0.71 nm peak of chlorite at 0.47 nm. Results indicate that the clay mineral composition of the Heishan loess deposition is mainly composed of illite and vermiculite(including hydroxyl-interlayered mineral(+HIM)) ranging from 70.9% to 82.2%. The contents of kaolinite, chlorite and smectite are relatively low. Compared with the glacial loess L₁, the interglacial paleosol S₁ contained higher levels of vermiculite(+HIM) and kaolinite, while the contents of illite, chlorite and smectite are relatively low. Moreover, the illite crystallinity(KI) and chlorite ratio(0.47/0.71 nm), which reflect the chemical weathering intensity indicators of illite and chlorite, are significantly higher in the paleosol S₁ samples than in the loess L₁ samples. The clay mineral assemblages and the higher illite crystallinity(KI) and chlorite ratio(0.47/0.71 nm) in the paleosol S₁ indicate a warm temperate humid to sub-humid climatic environment during the interglacial period. In the last glacial period, the loess L₁ from the CSM contains more detrital vermiculite(+HIM) than those of loess L₁ from the Chinese Loess Plateau, which indicates the eolain deposits in the northern piedmont of the CSM are not derived from dust blown from the deserts in the northwest China. This further proves the conclusion that the loess in the northern piedmont of the CSM was mainly derived from various types of sediments in the North China Plain, as inferred by the geochemical and grain-size analysis(Peng et al., 2016).
Key words:clay minerals/
loess-paleosol/
the Central Shandong Mountains region/
weathering/
loess provenance



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