Depositional processes of reworked tephra from the Late Pleistocene Youngest Toba Tuff deposits in the Lenggong Valley, Malaysia

Reworked tephra from the Late Pleistocene Youngest Toba Tuff (YTT) deposits in Malaysia's Lenggong Valley exhibit complex sedimentological characteristics that challenge traditional distinctions between primary and reworked tephra. Analysis of particle-size distributions, magnetic susceptibility, and mineralogical associations revealed that reworked tephra can mimic primary deposits, highlighting the limitations of particle size alone for differentiation. The study identified three depositional facies—flood flow, mudflow, and slumping—suggesting rapid accumulation over days to months. While Kampung Luat 3 emerged as a potential site for paleoenvironmental reconstructions due to distinct ash phases, the study cautions against overreliance on reworked tephra records, given uncertainties about time lags and site-specific modifications.

Gatti, E., Saidin, M., Talib, K., Rashidi, N., Gibbard, P., & Oppenheimer, C. (2013). Depositional processes of reworked tephra from the Late Pleistocene Youngest Toba Tuff deposits in the Lenggong Valley, Malaysia. Quaternary Research, 79(2), 228–241. https://doi.org/10.1016/j.yqres.2012.11.006