Academic Journal
Multiple Evolution Modes of Megaripples in the Qaidam Basin and Implications for Ripple‐Like Aeolian Landforms on Mars.
| Title: | Multiple Evolution Modes of Megaripples in the Qaidam Basin and Implications for Ripple‐Like Aeolian Landforms on Mars. |
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| Authors: | Li, Chao1 (AUTHOR) lichao256237@snnu.edu.cn, Zhang, Zhi1 (AUTHOR) zhi.zhang@snnu.edu.cn, Yu, Lupeng2 (AUTHOR), Chen, Guoxiang1 (AUTHOR), Yang, Junhuai3 (AUTHOR), Dong, Zhibao1 (AUTHOR) |
| Source: | Journal of Geophysical Research. Earth Surface. Mar2024, Vol. 129 Issue 3, p1-27. 27p. |
| Abstract: | Aeolian landforms provide valuable insights into the planetary surface environment and its evolutionary history. In this study, the formation and evolution of megaripples in the Qaidam Basin and their relationship with the development environment are analyzed. By quantifying the wind environment, morphology, grain‐size distribution, sedimentary structure, and luminescence age of megaripples, we propose for the first time that there are multiple megaripple evolution modes. Investigation revealed that three evolution modes were responsible for forming megaripples in different equilibrium states: transient, stable, and metastable. Well‐sorted coarse sand grains accumulate on ridges and overlay poorly sorted fine sand grains to form transient megaripples. Stable megaripples have alternating sedimentary bedding of coarse and fine sand grains. Metastable megaripples have a secondary ripple formation on the surface. Throughout their formation, coarse and fine sand grains undergo regrouping. The response of coarse grains to the change in wind speed lags behind that of fine grains. This process controls the erosion and accumulation of megaripples and affects their size and sedimentary structures. The evolution mode, scale, and sedimentary structure of megaripples are influenced by the grain‐size range under the same wind conditions. The luminescence ages of the coarse‐grained megaripple sediments are less than 700 years. This study provides a fresh perspective on the coexistence of various sand ripples and transverse aeolian ridges found on Mars. Plain Language Summary: Megaripples are intermediate‐scale landforms between sand ripples and dunes, with heights of tens of centimeters and wavelengths of up to 20 m. Megaripples contain valuable environmental information. This makes them important for understanding the planetary environment and evolution. Fieldwork in the Qaidam Basin has shown that megaripples of varying shapes and sizes are formed through diverse evolution modes. We identified and elaborated on three models of megaripple formation by studying the wind patterns, shape, grain‐size distribution, sedimentary structure, and age of megaripples at three sites in the Qaidam Basin. Transient megaripples consist of coarse sand grains on their upper half and poorly sorted fine sand grains on their lower half. Stable megaripples have alternating layers of coarse and fine sand grains that correspond to different aeolian sand‐transport intensities, and metastable megaripples have secondary sand ripples on the surface due to transient strong wind causing the saltation of coarse sand grains. Changes in the wind strength regroup the fine and coarse sand, which drives the bimodal distribution of the sand grains, and the sediment grain size controls the evolution mode, sedimentary structure, and scale. This provides insights into the spatial pattern of ripple‐like aeolian landforms on Mars. Key Points: Megaripples have various evolution modesDuring the formation of megaripples, coarse and fine sand grains undergo regroupingThe grain‐size range plays a crucial role in facilitating the coexistence of multi‐scale megaripples [ABSTRACT FROM AUTHOR] |
| Subject Terms: | *Sand dunes, *Landforms, Sedimentary structures, Planetary surfaces, Wind speed, Grain size |
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| ISSN: | 21699003 |
| DOI: | 10.1029/2023JF007417 |
| Database: | GreenFILE |
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