Geological setting and lithostratigraphy of the Lesser Himalaya in the Mugling-Banspani area, central Nepal

Abstract

The Lesser Himalaya in central Nepal is a fold-and-thrust belt with a complex stratigraphy and structure. In the present study, detailed geological mapping was carried out in the Mugling-Banspani area based on stratigraphic units proposed by Stocklin and Bhattarai (1977) to reveal the geological setting and lithostratigraphy of the area. The study shows that the area is occupied by the low-grade metasedimentary rocks of the Lower Nawakot Group. However, there are several discrepancies in classification of the rocks of the Lower Nawakot Group and their classification does not correspond with the field realities. The Anpu Quartzite thought to be the oldest unit of the Nawakot Complex laterally joins to the Fagfog Quartzite. Similarly, the Banspani Quartzite and Labdi Phyllite laterally join to the Purebensi Qu artzite and Dandagao n Phyllite, respectively. Si milar ly, the Nourpul Formation is clearly divisible into three members with distinct lithological characteristics. Based on the above facts, a revise d stratigraphic classification has been proposed for the rocks of the Lower Nawakot Group in the Mugling­ Banspani area. The Lower Nawakot Group can be divided into the oldest Kunchha Formation followed up section by the Fagfog Quartzite (~Anpu Quartzite), Dandagaon Phyllite (~Labdi Phyllite), Nourpul Formation and Dhading Dolomite. The Nourpul Formation comprises three members namely the Purebensi Quartzite, the Amdanda Phyllite and the Labdi Khola Carbonate. The Jalbire Syncline, Mugling Anticline, Aklang Syncline and the Anpu Anticline are the major geological structures of the study area.

Discrepancies and Research Gaps on the Lithostratigraphy of the Jajarkot Thrust Sheet, Western Nepal Himalaya

“…Likewise, the MCT has carried the older high-grade metamorphic crystalline rocks of the Higher Himalaya to the Lesser Himalaya. The regional geology of the Lesser Himalaya in Nepal is well-mapped (Figure), and its east-west extent is well documented (Stöcklin & Bhattarai, 1977;Dhital & Kizaki, 1987;Amatya & Jnawali, 1994;Paudel & Arita, 1998;Paudyal & Paudel, 2013;Dhital, 2015).…”

“…Stratigraphic classification of thrust sheets like the Kathmandu Nappe, Kahun Klippe and Jajarkot Thrust Sheet have been assigned by various researchers Ohta et al, 1973;Hirayama et al, 1988;Amatya & Jnawali, 1994;Dhital et al, 2002;Paudyal & Paudel, 2011, 2013Paudyal, 2014;Sah, 1999Sah, , 2007.…”

“…A massive thrust sheet covers a large area in central Nepal near Kathmandu (Stöcklin & Bhattarai, 1977;Stöcklin, 1980). A thrust sheet has been mapped in the Mugling-Damauli section, and the rocks of this thrust sheet have been correlated with the nearby nappes and klippes (Paudyal & Paudel, 2013;Paudyal, 2014). The Jajarkot Thrust Sheet is a large thrust sheet in western Nepal (Sharma, 1980;Kansakar, 1991Kansakar, , 1992Dhital, 2015;Soucy La Roche, 2018).…”

Geological Exploration, Landslide Characterization and Susceptibility Mapping at the Boundary between Two Crystalline Bodies in Jajarkot, Nepal

“…Within the study area, there are four megascopic structures: the south-dipping Thalaha Thrust (TT), the gently north-dipping Main Central Thrust (MCT), and two large-scale gently plunging, non-cylindrical syncline and anticline fold, Suwa Gad Anticline (SA) and Bhoor Syncline (BS) (Figure 2). The Thalaha Thrust, named after the village Thalaha in the present study, is equivalent to the Mahabharat Thrust (MT) [43] of the Kathmandu Nappe and the Dubung Thrust of the Kahun Klippe [44]. The MCT overrides the Lesser Himalayan rocks and places it over the high-grade metamorphic rocks of the Higher Himalayan crystalline slab.…”

Lithostratigraphy and metamorphism of the Khudi-Tal area, west central Nepal

“…The research in the Lesser and Higher Himalaya are mainly focused in geological evolution, tectonics, petrography, micro-tectonics, metamorphism, structural studies and geochronology (Gansser, 1964;Le Fort, 1975;Pêcher, 1977;Stöcklin and Bhattarai, 1977;Colchen et al, 1986Colchen et al, , 1980Stöcklin, 1980;Arita, 1983;Hodges et al, 1988Hodges et al, , 1996Harrison et al, 1997;Paudel and Arita, 2000;Catlos et al, 2001;Avouac, 2003;Gehrels et al, 2003;Martin et al, 2005;Pearson and DeCelles, 2005;Wobus et al, 2005;Bollinger et al, 2006;Kohn, 2008;Searle et al, 2008;Corrie and Kohn, 2011;Paudyal and Paudel, 2011;Nadin and Martin, 2012;Khanal and Robinson, 2013;Godard et al, 2014;Dhital, 2015). The Higher Himalaya of Western Nepal consists of Mesoproterozoic to Early Palaeozoic medium to high-grade metasedimentary rocks and crustal melts (Parrish and Hodges, 1996).…”