Abstract:
This paper addresses a distinctive event bedset encased by coastal erg-margin deposits, at a preferred stratigraphic level near
the base of the Neoproterozoic Upper Bhander Sandstone in central India. The bedset is composed of couplets of sandstone
beds that exhibit incisive amalgamation although they differ in geometry, structures (at soles, within and at tops of beds),
vertical grain-size variation as well as palaeocurrent pattern and direction. The wide extent of the bedset is evident from
several exposures spread over a distance of more than 50 km roughly in strike-parallel direction. Flow and depositional
dynamics interpreted from the coupled event beds are more consistent with a tsunami origin than alternative
palaeogeography-compatible models of climate-induced storm, flash flood or accentuated tide deposits. A palaeotsunamiite
model is thus discussed, with separate incoming and outgoing components. Considering the overall depositional setting to be
an epeiric sea coast in an intracratonic sag basin, the relevant bedset is inferred to reflect the record of a teletsunamiite; it
would also be one of the very few Precambrian tsunamiites known so far. Exceptional preservation of this possible tsunamiite
was facilitated by sheltered deposition behind the backshore zone and the berm, as well as by rapid burial by wind-deflated
sands and advancing aeolian dunes.
