Wang et al. (2026) Westerly reorganization driven by orbital forcing: Late Miocene aridification in the Tarim Basin, Central Asia

Identification

• Journal: Global and Planetary Change
• Year: 2026
• Date: 2026-04-01
• Authors: Dong Wang, Qingqing Qiao, Chuang Xuan, Zhuangzhuang Lv, Sunyi Dong, Gangqiang Li, Long Ma, Yudong Chen, Zhanwei Lin, Zhongyin Gao
• DOI: 10.1016/j.gloplacha.2026.105466

Research Groups

• Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, China
• State Key Laboratory of Ecological Safety and Sustainable Development in Arid Lands, Xinjiang Institute of Ecology and Geography, Chinese Academy of Sciences, Urumqi, China
• University of Chinese Academy of Sciences, Beijing, China
• Xinjiang Key Laboratory of Mineral Resources and Digital Geology, Urumqi, China
• School of Ocean and Earth Science, National Oceanography Centre Southampton, University of Southampton, Southampton, United Kingdom
• Research Center for Ecology and Environment of Central Asia, Chinese Academy of Sciences, Urumqi, China

Short Summary

This study utilizes high-resolution multi-proxy records from the western Tarim Basin to demonstrate that Late Miocene aridification (~8.1 Ma) was primarily driven by eccentricity-paced Antarctic ice sheet expansion, which reorganized Northern Hemisphere westerlies and amplified Central Asian aridification.

Objective

• To reconstruct orbital-scale hydroclimate variability in the western Tarim Basin during the Late Miocene (~9.1–7.28 Ma) and elucidate its linkage to the evolution and reorganization of the mid-latitude westerlies, thereby providing insights into the mechanisms driving long-term climate change in arid Central Asia.

Study Configuration

• Spatial Scale: Kashi Depression, western Tarim Basin, Central Asia (Xinjiang, northwestern China).
• Temporal Scale: Late Miocene, approximately 9.1 to 7.28 million years ago.

Methodology and Data

• Models used:
  • Acycle 2.8 (for pre-processing, pre-whitening, Gaussian band-pass filtering)
  • 2π Multi-Taper Method (MTM) in the SSA-MTM Toolkit (for spectral analysis)
  • Qgrain software (for grain size data processing)
  • Bayesian spectral analysis
  • Monte Carlo simulations
• Data sources:
  • High-resolution multi-proxy records from a 460 meter (m) thick fluvial-lacustrine succession (Pakabulake Formation) in the Kashi Depression, western Tarim Basin.
  • Proxies: Mass-specific low-field magnetic susceptibility (χlf), anhysteretic remanent magnetization (ARM), χARM, Rb/Sr ratio, mean grain size, V, Zn, Ti, Zr concentrations.
  • Magnetostratigraphy (Qiao et al., 2016) for age model.
  • External comparative data: deep-sea Mn nodule P₂O₅, eolian dust mass accumulation rates (MAR) at ODP Sites 885/886, illite/smectite ratios at IODP Site U1430, loess accumulation rates on the Chinese Loess Plateau, equatorial Pacific sea-surface temperature (SST), global deep-sea δ18Obenthic, δ18Obenthic from ODP1148.

Main Results

• A pronounced aridification event occurred in the western Tarim Basin at approximately 8.1 Ma, indicated by consistent increases in magnetic susceptibility (χlf, χARM), higher Rb/Sr ratios, finer mean grain sizes (increased <4 micrometer (μm) aeolian fraction, decreased 32–125 μm fluvial fraction), and localized gypsum deposition.
• Spectral analyses of the proxy records reveal dominant orbital-scale periodicities: ~405 kiloyear (kyr) and ~100 kyr eccentricity cycles in all proxies, and a ~41 kyr obliquity signal specifically in the mean grain-size record.
• The ~8.1 Ma aridification event is primarily attributed to orbital forcing, with progressive tectonic processes establishing a long-term arid background but not directly driving the abrupt aridification.
• Eccentricity-driven Antarctic ice sheet expansion led to global cooling, enhanced meridional temperature gradients, and reorganized Northern Hemisphere westerlies through hemispheric teleconnections.
• These reorganized westerlies modulated Central Asian hydroclimate, amplifying inland aridification in the Tarim Basin by reducing moisture transport.
• Low obliquity further influenced high-latitude insolation, contributing to polar cooling and reinforcing atmospheric circulation changes, including a northward migration of the westerlies that reduced moisture availability to the Tarim Basin.

Contributions

• Provides the first high-resolution, orbital-scale paleoclimate records for the Late Miocene (~9.1–7.28 Ma) in the western Tarim Basin, addressing a critical gap in understanding Central Asian hydroclimate evolution.
• Demonstrates that an orbitally forced ice sheet-westerly system exerted primary control on Late Miocene inland Asian aridification.
• Proposes a physically coherent mechanism linking eccentricity-driven Antarctic ice sheet expansion, equatorial Pacific cooling, enhanced meridional temperature gradients, and reorganization of Northern Hemisphere westerlies to Central Asian aridification.
• Rigorously distinguishes the role of orbital forcing as the immediate trigger for the ~8.1 Ma aridification event from the long-term tectonic conditioning of aridity in the region.
• Offers critical insights for understanding past climate transitions and improving projections of future hydroclimate change in arid Central Asia.

Funding

• “Western Young Scholars” Fund of Chinese Academy of Sciences (CAS) (2022-XBQNXZ-005)
• National Natural Science Foundation of China (Grant 42122028, 42474100, 41774077, 42488201)
• National Key Research & Development Program of China (2023YFF0803500)
• Natural Science Foundation of Xinjiang Uygur Autonomous Region (2024D01E34)
• International Partnership Program of Chinese Academy of Sciences (Grant 131551KYSB20200021)
• Project of Theory of Hydrocarbon Enrichment under Multi-Spheric Interactions of the Earth (THEMSIE)
• IGCP 662

Citation

@article{Wang2026Westerly,
  author = {Wang, Dong and Qiao, Qingqing and Xuan, Chuang and Lv, Zhuangzhuang and Dong, Sunyi and Li, Gangqiang and Ma, Long and Chen, Yudong and Lin, Zhanwei and Gao, Zhongyin},
  title = {Westerly reorganization driven by orbital forcing: Late Miocene aridification in the Tarim Basin, Central Asia},
  journal = {Global and Planetary Change},
  year = {2026},
  doi = {10.1016/j.gloplacha.2026.105466},
  url = {https://doi.org/10.1016/j.gloplacha.2026.105466}
}