Lithostratigraphy of the Siwalik Group, Khutia Khola section, Far Western Nepal Himalaya

Abstract

The Neogene fl uival sediments (Siwalik Group) forming the southernmost hills in the Himalaya is well exposed along the Khutia Khola in the Far Western Nepal. The newly established lithostratigraphy is subdivided into the Jagati Formation (2110 m, equivalent to the Lower Siwalik) and the Kala Formation (2050 m, equivalent to the Middle Siwalik) in ascending order. Each formation is further divided into three members; the lower, middle and upper, based on the ratio of mudstone vs. sandstone beds as well as color and grain size of sandstone. The Jagati Formation is characterized by reddish-brown mudstones interbedded with very fi ne-to coarse-grained sandstones. Paleosols characterized with burrows, rhizoliths, desiccation cracks, concretions and nodules are present in higher proportion than thinly laminated or massive mudstone beds. The Kala Formation comprises thin-to thick-bedded, very fi ne-to very coarse-grained sandstones and pebbly sandstones interbedded with reddishbrown, greenish-grey to dark-grey mudstones. Sandstone beds exhibit "salt and pepper" appearance. In the lower part of the upper member sub-rounded to rounded pebbles are scattered along with trough and planar cross-laminations in sandstone beds, whereas the gravel size tends to be larger and few cobble size gravels also appear in the upper part. Thinly laminated or massive mudstones are common and paleosols are less frequent. The age of the boundary between the Jagati and Kala Formations (Lower-Middle Siwaliks) is around 11.05 Ma. The boundaries age between the middle and upper members of the Jagati Formation is around 12.7 Ma and between the lower and middle members of the Kala Formation is around 9.0 Ma. The dominance of fi ner sediments and thinner sandstone units than that of neighboring Siwalik successions indicate the fl uvial facies of the Khutia Khola section is deposited by a small river system and may represent the interfl uve setting of major river systems.

Erosional unroofing of Himalaya in far western Nepal: a detrital zircon U-Pb geochronology and petrography study

“…A lithostratigraphic study in Karnali River section has shown that the paleo-Karnali River had a large drainage basin system, which accommodate the sediments from Higher Himalaya, earlier than rest of the sections in Central Himalaya (Sigdel et al 2011). However, in Khutia Khola section (~50 Km west of the Karnali River) the fluvial facies during the Neogene was interfluve setting of major streams (Adhikari and Sakai 2015).…”

Review of the Geology of the Arun-Tamor Region, Eastern Nepal: Present Understndings, Controversies and Research Gaps

“…In Nepal, the Siwalik succession is 4-6 km thick and represents a coarsening upward sequence of rocks, i.e. shale, mudstone, siltstone, fine sandstone at basal part, followed by a medium to coarse salt-pepper sandstone, pebbly-sandstone at middle section, while pebble-cobble to boulder conglomerate at the upper section, with fining up cycles (Tokuoka et al, 1990;Dhital et al, 1995;Ulak, 2004Ulak, , 2009Sigdel et al, 2011;Adhikari & Sakai, 2016). The distribution of these sedimentary successions is comparatively narrow in the Arun-Tamor section, in comparison with the western regions where wide distribution is accompanied by the presence of dun valleys.…”

Is male out‐migration associated with women's participation in post‐disaster rebuilding? Evidence from Nepal after the 2015 Gorkha earthquake

“…However, the relationship between male out-migration and women's behaviour is far from clear. While scholars have theorised that male out-migration could increase a household's economic resources and empower women to fill vacant decision-making and labour roles (see, for example, Hondagneu-Sotelo, 1994), recently, researchers have begun to investigate how the potential empowering effects of out-migration can interact with factors such as family structures or remittance levels (Lokshin and Glinskaya, 2009;Maharjan, Bauer, and Knerr, 2012;Sadiqi and Ennaji, 2012;McEvoy et al, 2012;Adhikari and Hobley, 2015;Eastin, 2018;Pandey, 2021). Where women are supported by these factors, their autonomy in relation to household decisions and mobility might increase.…”