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<p>Seismogenic structures and sequences preserved in sediments are important archives of paleo-seismic events and regional tectonism. However, investigations of such features have been limited in pre-Quaternary aeolian deposits. Here sedimentological analysis of the 8.3–7.0 Ma interval in Neogene aeolian deposits in the Xihe Basin, western Qinling Mountains, identified multiple layers characterized by abrupt inputs of sandy gravels. These gravel clasts were derived from bedrock in piedmont zones and exhibit subaerial depositional features without significant involvement of flowing water, suggesting earthquake-triggered collapse and landslide due to active tectonism. At least eight paleo-seismic events were identified in the section, which can be clustered into six seismic episodes that occurred predominantly in two stages (8.3–8.0 and 7.6–7.0 Ma). This paleo-seismic record indicates that the western Qinling Mountains experienced a tectonically active phase during 8.3–7.0 Ma in response to the expansion and uplift of the northeastern Tibetan Plateau, which occurred in a two-stage, multiepisode deformation process. The well-preserved aeolian sequences with minimal erosion and deformation imply that there were no significant changes in topography due to uplift in the western Qinling Mountains during this period. Our findings highlight the significance of aeolian deposits in reconstructing paleo-seismic activities and deciphering intricate regional tectonism.</p>

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Late Miocene paleo-seismic events and tectonic responses of the western Qinling Mountains recorded in aeolian deposits

  • 期刊论文

  • 发表日期：

    2025年4月18日

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  • Long Chen,
  • Zhengtang Guo,
  • Xin Zhou,
  • Junyi Ge,
  • Chaoqin Chen,
  • Zhilin He

摘要

Seismogenic structures and sequences preserved in sediments are important archives of paleo-seismic events and regional tectonism. However, investigations of such features have been limited in pre-Quaternary aeolian deposits. Here sedimentological analysis of the 8.3–7.0 Ma interval in Neogene aeolian deposits in the Xihe Basin, western Qinling Mountains, identified multiple layers characterized by abrupt inputs of sandy gravels. These gravel clasts were derived from bedrock in piedmont zones and exhibit subaerial depositional features without significant involvement of flowing water, suggesting earthquake-triggered collapse and landslide due to active tectonism. At least eight paleo-seismic events were identified in the section, which can be clustered into six seismic episodes that occurred predominantly in two stages (8.3–8.0 and 7.6–7.0 Ma). This paleo-seismic record indicates that the western Qinling Mountains experienced a tectonically active phase during 8.3–7.0 Ma in response to the expansion and uplift of the northeastern Tibetan Plateau, which occurred in a two-stage, multiepisode deformation process. The well-preserved aeolian sequences with minimal erosion and deformation imply that there were no significant changes in topography due to uplift in the western Qinling Mountains during this period. Our findings highlight the significance of aeolian deposits in reconstructing paleo-seismic activities and deciphering intricate regional tectonism.