Nannoliths abundance and distribution in tsunami deposits: example from the December 26, 2004 tsunami in Lhok Nga (northwest Sumatra, Indonesia)

摘要: Nannoliths are heterogeneous morphological suites of biogenic carbonate particles with silt-clay size dimensions. They mainly composed coccoliths, a suite calcite complex structures produced by marine coccolithophores belonging to the Haptophyta microalgae division. Coccoliths can be found in and coastal facies, they used as palaeoenvironmental proxy tracer sediments. Among microscopic commonly observed tsunami deposits, diatoms often determine provenance sediment source, but very few investigations about nannoliths were carried out so far. In this paper, we investigate abundance, distribution 2004 deposits near Lhok Nga (northwest Sumatra, Indonesia) their implications terms sources flow dynamics. The display abundances that significantly higher (1.0 x 104 7.2 nn/g) than other (4.5 103 nn/g), lower innershelf (1.3 6.9 105 nn/g). Such enrichments could represent tool recognize palaeo-tsunami deposits. A remarkable characteristic is nannolith assemblages despite relative impoverishment clay content, which under normal hydrodynamic conditions would prevent settle. abundance tends decrease landward upward, variations due successive erosion/sedimentation phases waves, topographical effects. When coupled grain-size analyses, study vertical trends thus represents complementary data for interpreting