Micromorphology to Distinguish Diagenetic Overprinting and Paleopedogenic Features in Lithified Paleosols of the Himalayan Foreland Basin

This chapter provides the micromorphological guidelines to identify paleopedogenic features in lithified paleosols that were influenced by burial diagenesis up to ~7.5 km depth in the Himalayan foreland basin. The fluvial sequence of the Dagshai Formation and Dharamshala Formation of ~31 Ma age in the NW Himalaya shows four types (Type-I to Type-IV) of paleosols with an increase in abundance of well-developed lithified paleosols in the lower part of the Dagshai and Dharamshala Formations. The 7.5 km burial has resulted in 54–78% compaction, cementation by iron oxide, plugging of voids, disruption of the paleopedofeatures, fracturing and breaking down of large mineral grains and pedogenic nodules, coarsening of the pedogenic calcite, and the mineralization of the root channels. Given the diagenetic overprinting, it is not easy to identify and interpret the paleopedogenic events and processes in these lithified paleosols. However, micromorphology has helped to distinguish digenetic overprinting and paleopedogenic features to reconstruct the paleopedogenic history and paleoenvironments of these lithified paleosols. The paleopedogenic features of these paleosols suggest humid to sub-humid conditions during their formation in the early Oligocene (~31 Ma) time.