Sequence Stratigraphy of Dalmiapuram formation, Kallakudi Quarry - II, South India

A sequence stratigraphic framework is worked out for the first time for the Dalmiapuram Formation exposed in Kallakudi quarry near Kallakudi village in Tiruchirapalli District. Thc complete lithological succession of this formation is designated as 'Dalmiapuram Sequence' of latest Albian - Cenomanian age and consists of grey shale, coral/algal limestone and bedded biostromal limestone and marl in ascending order. Grey shale rests unconformably ovcr thc Archaean basement. This contact forms the lower sequencc boundary of Dalmiapuram Sequence. The middle lithounit, the coral algal limestone rests ovcr grey shale. This unit abruptly grades into bedded limestone/marl alternations. This abrupt termination of coral algal limestone may be due to relative sea level rise and possibly this surface represents 'drowning unconformity'. The upper lithounit, which has alternating bands of biostromal limcstonc and marl, might indicatc cyclic carbonate precipitation (?Milankovich cycles). This unit is unconformably overlain by Neogene Cuddalore sandstone. This unconformity surface represents the upper boundary of the sequencc. The entire Dalmiapuram Sequence appears to have been deposited as Transgressive Systems Tract (TST) dcposit and got exposed as a result of basinal rise.