Integrated lithofacies, microfacies and sequence stratigraphic framework of the Takche Formation (Ordovician- Early Silurian), Pin Valley, Spiti Himalaya, India

An integrated litho-microfacies and sequence stratigraphic analysis of the Takche Forma-tion (Ordovician-Silurian) has been carried out in the Pin Valley, Spiti region. Ten lithofacies were identified in the Takche Formation, i.e. (i) siltstone-sandstone facies, (ii) sandy limestone facies A, (iii) sandy limestone facies B, (iv) sandy limestone facies C, (v) sandy limestone facies D, (vi) calcar-eous shale-siltstone facies, (vii) fossiliferous limestone facies, (viii) nodular/ribbon mudstone facies, (ix) bedded sandstone facies and (x) silicified sandstone-siltstone facies. The rocks of the Takche Formation belong to nine distinct microfacies characteristic for a shallow marine carbonate ramp deposited under highly fluctuating energetic condition. The sequence stratigraphic analysis of the Takche Formation in the Pin Valley revealed the presence of three sequences (S1-S3), two maximum flooding surfaces (MFSs) and five upward shoaling cycles indicating transgressive and regressive events. The three disconformity surfaces (U1-U3) resulted from submarine erosion or rapid fall in relative sea-levels.

Automated summary

An integrated litho-microfacies and sequence stratigraphic analysis was conducted on the Takche Formation (Ordovician-Silurian) in the Pin Valley, Spiti region. Ten lithofacies were identified, indicating deposition in a shallow marine carbonate ramp with highly fluctuating energetic conditions. The sequence stratigraphic analysis revealed three sequences, two maximum flooding surfaces, and five upward shoaling cycles, suggesting transgressive and regressive events. The presence of three disconformity surfaces resulted from submarine erosion or rapid fall in relative sea-levels.