| 引用本文: | 程夏丽,安福元,李善禄,徐一帆,张清纯,李斌凯.2025.察尔汗盐湖沉积中磁化率、Rb/Sr值的异常相关性及其环境意义[J].地球环境学报,16(2):166-177, 205 |
| CHENG Xiali,AN Fuyuan,LI Shanlu,XU Yifan,ZHANG Qingchun,LI Binkai.2025.The abnormal correlation of magnetic susceptibility and Rb/Sr ratio in Qarhan Salt Lake and its environmental significance[J].Journal of Earth Environment,16(2):166-177, 205 |
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| 摘要: |
| 沉积序列中磁化率与Rb/Sr值的相关性在常规情况下受控于其风化过程、沉积相性质和物源。然而，处于干旱区湖泊的湖相沉积物由于混入了大量风成物质，造成其物源具有明显的二元性，研究这种特殊沉积物的上述两种环境指标及其相关性对于准确理解区域气候和风化过程具有重要意义。分析察尔汗盐湖ISL1A钻孔序列中含风成组分样品的磁化率、Rb/Sr值相关性，并与柴达木盆地西部古湖相表土样品的磁化率、Rb/Sr值及区域环境指标进行对比，结果表明：（1）钻孔样品的磁化率与Rb/Sr值在不同气候阶段变化趋势总体呈正相关，不同于经典湖相沉积中两者呈负相关关系，但与黄土-古土壤序列中的相关性一致，表明干旱区湖相沉积中大量风成物质的加入显著影响磁化率与Rb/Sr值的相关性；反之，通过两个指标的相关性分析，亦可判别干旱区湖相沉积中的风成信号；（2）钻孔中的磁化率和Rb/Sr值代表了柴达木-东昆仑盆山系统中各地区整体的风化强度，可反演该地区的历史风化过程；（3）晚更新世以来在冰期-间冰期（冰阶-间冰阶）旋回尺度上柴达木-东昆仑盆山系统的风化程度与季风和西风的转换及其强弱密切相关。 |
| 关键词: 察尔汗盐湖 湖相沉积 风成物质 磁化率 Rb/Sr值 风化过程 |
| DOI：10.7515/JEE222092 |
| CSTR：32259.14.JEE222092 |
| 分类号: |
| 基金项目:国家自然科学基金项目（42371019，41961014）；青海省基础研究计划（2020-ZJ-727）；青海省“昆仑英才·高端创新创业人才”计划 |
| 英文基金项目:National Natural Science Foundation of China (42371019, 41961014); Basic Research Program of Qinghai Province (2020-ZJ-727); The Kunlun Elite High-End Innovation and Entrepreneurship Talent Program of Qinghai Province |
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| The abnormal correlation of magnetic susceptibility and Rb/Sr ratio in Qarhan Salt Lake and its environmental significance |
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CHENG Xiali1, 2, AN Fuyuan1, 2, 3*, LI Shanlu4, XU Yifan1, 2, ZHANG Qingchun1, 2, LI Binkai5
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1. Key Laboratory of Tibetan Plateau Land Surface Processes and Ecological Conservation (Ministry of Education), Qinghai Normal University, Xining 810008, China
2. Qinghai Province Key Laboratory of Physical Geography and Environmental Process, College of Geographical Science, Qinghai Normal University, Xining 810008, China
3. Academy of Plateau Science and Sustainability, People’s Government of Qinghai Province & Beijing Normal University, Xining 810008, China
4. Qinghai Geotechnical Engineering Survey Institute Co. Ltd., Qinghai Branch of China National Geological Exploration Center of Building Materials Industry, Xining 810008, China
5. Qinghai Provincial Key Laboratory of Geology and Environment of Salt Lakes, Qinghai Institute of Salt Lakes, Chinese Academy of Sciences, Xining 810008, China
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| Abstract: |
| Background, aim, and scope The correlation between magnetic susceptibility and Rb/Sr ratio in sedimentary sequences is inf luenced by several factors, including weathering processes, unitary sedimentary facies, and material sources. However, the presence of abundant aeolian materials incorporated into lake sediments within arid basins may lead to a complex relationship between these two proxies. Therefore, this study aimed to investigate the correlation between magnetic susceptibility and Rb/Sr ratio, which has great significance for accurately understanding regional climate and weathering processes. Materials and methods This study presents a lacustrine core (ISL1A) extracted from Qarhan Salt Lake of the Qaidam Basin and analyzes the correlation between magnetic susceptibility and Rb/Sr ratio for 176 samples of mixed aeolian materials in the lacustrine sediments. The discussion focuses on the magnetic susceptibility and Rb/Sr characteristics of palaeolacustrine strata in the western Qaidam Basin. Results The low-frequency susceptibility (χlf) and high-frequency susceptibility (χhf) curves demonstrated a high sensibility in relation to the Rb/Sr ratio. Therefore, they could be useful proxies for correction analysis with Rb/Sr ratio and for examining the aeolian signal of the lacustrine sediments. Discussion The magnetic susceptibility and Rb/Sr ratio in the ISL1A core exhibit positive correlation, which is consistent with the characteristics of loess deposits but in sharp contrast to the negative correlation commonly observed in lacustrine sediments. This anomalous relationship reflects the significant influence of substantial aeolian input on elemental geochemical behavior. Within the geomorphic context of the “high mountains and deep basins” of the Qaidam-East Kunlun basin-mountain system, the Qarhan Salt Lake sediments show a dual provenance controlled by both aeolian and fluvial sources, with the proportion of aeolian source contribution varying in response to climatic conditions. This duality not only affects the spatial and temporal distribution of elemental ratios but also indicates that regional weathering processes dynamically respond to shifts in sediment provenance and hydroclimatic alternations. Conclusions The two proxies represented the overall weathering intensity of the Qaidam-East Kunlun basin-mountain system since the Late Pleistocene, which was driven by monsoons and global westerlies on interglacial-glacial timescales. Recommendations and perspectives This study prompts us to distinguish the origin of the detrital input before evaluating the correlation between magnetic susceptibility and Rb/Sr ratio in lacustrine sediment sequences derived from arid basins. |
| Key words: Qarhan Salt Lake lake deposition aeolian material magnetic susceptibility Rb/Sr ratio the
weathering process |
