| 天体轨道参数调控柴达木盆地第四纪盐类资源形成的新模式 |
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| 引用本文：韩文霞,方小敏,张涛.2024.天体轨道参数调控柴达木盆地第四纪盐类资源形成的新模式[J].地球学报,45(5):715-727. |
| DOI：10.3975/cagsb.2024.070801 |
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| 基金项目:国家自然科学基金项目(编号: 42071111); 第二次青藏高原综合科学考察研究项目任务七专题七“高原风化剥蚀历史及气候环境效应”(编号: 2019QZKK0707) |
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| 中文摘要:盐类资源的形成受沉积盆地、干旱气候和物源补给三个关键因素的控制, 以往的研究主要关注构造、沉积环境和物源因素在成盐过程中的作用, 而忽视了干旱和极端干旱气候这一关键因素及其与盆地盐层形成的耦合机制。本文以中德联合在柴达木盆地西部察汗斯拉图凹陷获取的科学深钻为例, 运用磁学、元素和同位素地球化学等指标反演研究区的水文气候演化历史, 并通过时间域、频率域以及系统动力学演化特征等综合分析手段探究了深时气候变化的控盐机制和规律。结果表明, 柴达木盆地西部地区自2.7 Ma以来存在2.2~1.95 Ma、1.3~1.1 Ma、0.85~0.65 Ma和0.5~0.3 Ma四次关键的干旱化加剧和盐层发育期; 发现在天体轨道倾角低幅和低偏心率值的同步期, 会通过促进北半球冰盖扩张调控北半球中高纬西风环流的位置和强度, 进而影响柴达木盆地的气候和水文循环, 控制盆地内干旱事件的发生和盐层发育。在轨道-亚轨道-千年尺度上, 全球冰量和北半球高纬气候变化也显著地控制了柴达木盆地的干旱事件和盐层发育。柴达木盆地多个凹陷区的盐层对比结果进一步表明, 这一天体轨道特殊组合控制盆地的干旱事件和盐层发育过程的机制在全盆地具有普适性, 促使柴达木盆地多个不同凹陷区尽管盐层发育存在一些差异, 但其主要的盐层发育期均集中在上述四个关键时期。研究成果不仅为柴达木盆地乃至其他干旱区的成盐机制和深时发育规律提供了新的理论视角和研究思路, 而且为未来结合构造-气候-物源耦合研究, 对不同区域盐类资源发育类型和规律进行精细化研究, 以及深入探索深时盐层发育规律提供了重要的研究基础。 |
| 中文关键词:柴达木盆地 盐类资源 偏心率与倾角 北半球冰盖 西风环流 |
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| New Model for Orbital Forcing Salt Formation in the Qaidam Basin |
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| Abstract:The formation of salt resources is controlled by three key factors: sedimentary basins, arid climates, and source material replenishment. Previous studies have mainly focused on the notable roles of tectonic activity and the sedimentary environment in the salt-forming process while neglecting the key factors of arid and extremely arid climate events and their coupling mechanisms in the formation of salt layers in basins. This study reconstructed the hydroclimatic evolutionary history of the Qaidam Basin based on a multidisciplinary analysis, including rock magnetism, environmental magnetism, elemental and isotopic geochemistry, and palynological studies on a deep drilling core in the Chahanslta Depression of the western Qaidam Basin. The salt formation process and related mechanisms were further investigated based on a comprehensive analysis of published and newly obtained data from the SG-1 core by tracing the temporal and frequency domain evolution patterns and the system dynamics evolution characteristics of these data. The results reveal four key periods of salt layer development in the western Qaidam Basin since 2.7 Ma, specifically during 2.2–1.95 Ma, 1.3–1.1 Ma, 0.85– 0.65 Ma, and 0.5–0.3 Ma. We suggest that reduced seasonality and increased meridional moisture transport, promoted by the co-occurrence of low obliquity amplitudes and low eccentricity, would have facilitated the ice sheet expansion in the Northern Hemisphere. This would have subsequently affected the climate and hydrological cycle of Qaidam Basin by regulating the position and intensity of the Northern Hemisphere westerlies, controlling the occurrence of arid events and the development of salt layers within the basin. Further comparative analysis confirmed that on orbital-suborbital-millennial scales, global ice volume and climate change in the high latitudes of the Northern Hemisphere notably control the arid climate and salt layer development in the Qaidam Basin. This orbital parameter controlling the arid climate evolution and the salt-forming process has been shown to be applicable throughout the entire basin. This leads to the development of salt layers in different depressions of the Qaidam Basin, despite bearing some differences, the development of their major salt layer predominantly concentrated in the aforementioned four key periods. These research findings offer novel theoretical insights and methodological approaches for understanding the processes and mechanisms underlying salt formation in the Qaidam Basin and other arid areas. Furthermore, these findings provide a remarkable foundation for future studies that will explore the interplay between tectonic, climatic, and source material variations to delineate the diverse types and patterns of salt resource development across various regions as well as unravel the deep-time evolution of these salt resources. |
| keywords:Qaidam Basin salt resources eccentricity and obliquity northern hemisphere ice sheets westerlies |
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