Late Archaean tidalites from western margin of Chitradurga greenstone belt, southern India

• First report of Late Archaean tidal sediments from India.
• Tidal sedimentation in 2.8–2.6 Ga old Chitradurga greenstone belt, India.
• Neap–spring cyclicity in a Late Archaean semidiurnal tidal system.

Tidalites are preserved within a metavolcano-sedimentary succession of the Late Archaean Bababudan Group (Dharwar Supergroup) along the western boundary of the NNW-SSE trending Chitradurga greenstone belt, West Dharwar Craton, southern India. These may represent the oldest record of tidal processes in peninsular India. Millimetre thick sand–mud alternations, bidirectional cross-strata, mudstone-draped sandy foresets, reactivation surfaces indicating time–velocity asymmetry, sigmoidal cross-strata and mudstone draped flaser/lenticular bedding are displayed by the sandstone mudstone heterolithic facies in the upper part of the Bababudan succession, together implying a tidal depositional system. Thick–thin pairs of rhythmic foreset bundles correspond to neap–spring tidal cycles within a semidiurnal tidal system. Development of the studied coastal sediments suggests formation of stable platform along the western margin of the late Archaean Chitradurga greenstone belt.