EGU24-7403, updated on 08 Mar 2024
EGU General Assembly 2024
© Author(s) 2024. This work is distributed under
the Creative Commons Attribution 4.0 License.

Quaternary volcanism in southeastern Tibetan Plateau: A record of stagnant oceanic slab in the mantle transitional zone

Huan Kang1, Yongwei Zhao2, Xiaoran Zhang3,4, Liyun Zhang5, Huiping Zhang1, and Haibo Zou6
Huan Kang et al.
  • 1Institute of Geology, China Earthquake Administration, China (
  • 2Key Laboratory of Active Tectonics and Volcano, Institute of Geology, Chinese Earthquake Administration, Beijing
  • 3State Key Laboratory of Lithospheric Evolution, Institute of Geology and Geophysics, Chinese Academy of Sciences
  • 4College of Earth and Planetary Sciences, University of Chinese Academy of Sciences
  • 5Key Laboratory of Tibetan Plateau Earth System, Environment and Resources, Institute of Tibetan Plateau Research, Chinese Academy of Sciences
  • 6Department of Geosciences, Auburn University

The Tibetan lateral mantle flow bears considerable significance in deciphering the material movement mechanisms within global plate convergence zones. However, the front edge of this mantle flow is unclear. Here we conduct petrological, geochronological, mineralogical, geochemical and Sr-Nd-Pb isotopic investigations on Quaternary intracontinental alkali basalts from the southwestern Yunnan (the south of 27°N), to determine the source characteristics and geodynamic mechanisms of the Quaternary alkali basalts in southeastern Tibetan Plateau and to trace the recent Tibetan mantle flow. Alkali basalts in the region are mainly basanite and trachybasalt with eruptions during the Pleistocene epoch. They possess a highly incompatible elemental and radiogenic Sr-Nd-Pb isotopic composition similar to those of the Ocean Island Basalts, consistent with melts derived from asthenospheric mantle with low-degree partial melting. Calculated magma-water contents of regional alkali basalts range from 1.32 ± 0.48 wt.% to 2.23 ± 0.18 wt.%, corresponding to 269 ppm to 3591 ppm water contents of their mantle source, which are significantly higher than that of the normal upper mantle (i.e., 50–250 ppm). Quantitative trace-element modelling and dramatic variations in oceanic crust-sensitive indicators such as Eu/Eu*, Sr/Sr*, Ce/Pb, (Nb/Th)N-PM and (Ta/U)N-PM indicate variable contributions of upper and lower oceanic crust to magma sources. Systematic examinations of petrological, geochemical, and geophysical evidence reveal that the temporary small-volume Quaternary volcanism in southeastern Tibetan Plateau is not related to Tibetan southeastward mantle flow but is primarily attributed to stagnant Neo-Tethyan slab in the mantle transition zone.

How to cite: Kang, H., Zhao, Y., Zhang, X., Zhang, L., Zhang, H., and Zou, H.: Quaternary volcanism in southeastern Tibetan Plateau: A record of stagnant oceanic slab in the mantle transitional zone, EGU General Assembly 2024, Vienna, Austria, 14–19 Apr 2024, EGU24-7403,, 2024.

Corresponding supplementary materials formerly uploaded have been withdrawn.