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- Title
Reconstructing Mollisol Formation Processes Through Quantified Pedoturbation.
- Authors
Zhang, Aimin; Long, Hao; Yang, Fei; Zhang, Jingran; Peng, Jun; Shi, Yonghui; Zhang, Ganlin
- Abstract
Mollisols are highly fertile soils and function as significant carbon reservoirs. However, determining their ages and formation processes is challenging due to extensive pedoturbation, which undermines conventional dating methods. Here, we employed luminescence, a light‐sensitive property of minerals widely used in geological dating, to investigate and quantify soil mixing. We analyzed over 2,400 luminescence ages of individual K‐feldspar grains from a Mollisol profile in Northeast China, and for the first time, we were able to determine the intensity of pedoturbation in the Mollisol profile over the past 50,000 years. The results showed that the current pedoturbation can penetrate to a depth of approximately 80 cm, with the intensity decreasing with depth. By identifying a significant intensification in historical pedoturbation, we inferred that the paleoenvironment might be suitable for the formation of Mollisols 16,400 years before present. Plain Language Summary: Mollisols, also known as a type of black soils, are highly fertile soils characterized by a thick, dark surface layer rich in soil organic matter. Mollisols are not only crucial for food security but also serve as a significant carbon pool. To predict the future evolution of these valuable soil resources, it is important to understand when and how they formed. However, due to intensive mixing by animals, plants, and freeze‐thaw processes, it is challenging to accurately obtain soil ages using traditional dating methods that rely on undisturbed sedimentation layers. Here, we utilized luminescence, a light‐sensitive property of minerals, to address the challenge of soil mixing. We analyzed more than 2,400 luminescence ages of individual K‐feldspar grains from a Mollisol profile in Northeast China. The results showed that the upper 80 cm of the soil body is currently mixed, with the mixing intensity being most intense at the soil surface and decreasing with depth. Additionally, we observed evidence of historical soil mixing over the past 50,000 years. The intensity of soil mixing increased around 16,400 years ago. We infer that the paleoenvironment might be favorable for forming Mollisols since then. Key Points: Single‐grain luminescence was used to quantify the intensity of pedoturbation in the Mollisol profile over the past 50,000 yearsDust accumulation fostered the formation of the thick, dark, humus‐rich surface layer of the Mollisol profileThe formation processes of the Mollisol profile were traced back to 16,400 years before present
- Subjects
BLACK cotton soil; THERMOLUMINESCENCE dating; MOLLISOLS; FREEZE-thaw cycles; MINERAL properties; LUMINESCENCE
- Publication
Geophysical Research Letters, 2024, Vol 51, Issue 11, p1
- ISSN
0094-8276
- Publication type
Article
- DOI
10.1029/2024GL108189