Facies Associations and Discontinuous Surfaces in the Syringothyris Limestone Formation of Tethyan Margin of Gondwana, Kashmir

Abstract

The early Carboniferous sedimentation of the Tethyan Margin of Gondwana in the Kashmir Himalaya represents alternating siliciclastic - carbonate succession consisting of distinct stratigraphic sequences which are bounded by discontinuities. The discontinuities in the sedimentation are related to environmental changes in the form of subaerial exposure, subaqueous erosion, subaqueous omission or changes in texture and facies. These distinct surface zones or time significant boundaries can be correlated across the depositional platform. Low stand, high stand and transgressive sedimentation units in the lower and middle parts of early Carboniferous Syringothyris Limestone Formation in Banihal area have been recognised. This is explained by superposition of high frequency and low amplitude sea level fluctuations on a large-scale trend under greenhouse conditions during the early Carboniferous period. The facies associations present in the early Carboniferous succession of the Himalaya broadly represent intertidal (peritidal), shallow subtidal, deeper subtidal, off-shore-slope and deeper environments. Discontinuities that are interpreted as progradational, retrogradational and aggradational phases of sedimentation bound these facies associations. This formation represents continental margin depositional setting which is authenticated by deposition of siliciclastic sediments. This marginal depositional setting is greatly affected by numerous dynamic processes including tectonic and other active sea as well as continental processes. The records of all those processes in this formation reflect the eustatic changes in sea level. These periodic eustatic changes have generated the various discontinuities, stratigraphic sequences or systems tracts. Overall it appears that interplay of many processes such as sediment supply, thermal and tectonic activity, eustatic and climatic changes in the Kashmir Tethyan depositional basin generated these distinct depositional sequences during the early Carboniferous period.