Facies characteristics and cyclicity of Lower Siwalik sediments, Jammu area: a new perspective

The Lower Siwalik succession of the Jammu area has been distinguished into three major lithofacies associations: a sand-dominant association, a sandy- mud-dominant association, and a siltyheterolithic association. The sand-dom inant association is made up of three lithofacies: cross-bedded sandstone. rippled silty sandstone and bioturbated sandy siltstone, which are organize d in multistoreyed sandbodies representing deposition in major river channe ls. The sandy-mud-dominant association is made up of two lithofacies, mottl ed clayey siltstone and interbedded sandstone, siltstone and mudstone, repr esenting deposition in overbank areas of flood-plain and natural levee-crev asse splays. The sand-dominant association and sandy-mud-dominant associati on are grouped together as a channel-related succession and are products of processes in the river channel. The silty-heterolithic association consist s of four lithofacies: mottled siltstone, mottled silty sandstone, bedded c alcrete and mottled mudstone. They are considered to be deposits of Doab (u pland interfluve) areas operating independently of present-day major river channels. These deposits have been formed in minor channels. sloping surfac es, and takes and ponds of the interfluve regions. The cyclicity of both su ccessions (channel-related and Doab-related) has been determined using a pa rtial-independence statistical model.