Lithostratigraphy and Structure of the Musikot-Khalanga Area, Western Nepal

Abstract

The study area encompasses the eastern portion of the Karnali Klippe and the Bheri tectonic window of Western Nepal, focusing on lithostratigraphy and geological structures. Geological mapping and cross-sections at a 1:25,000 scale detail the Lesser Himalayan Sequence and Higher Himalayan Crystallines in Musikot-Khalanga area. The Lesser Himalayan Sequence comprises sedimentary and low- to medium-grade metamorphic rocks, divided into the Kuchibang Formation, Deu Khola Formation, Puma Khola Dolomite, Morabang Formation, and Jibu Formation, respectively. The Thabang Formation constitutes the Higher Himalayan Crystallines. Major structures include the Main Central Thrust, Ghatte Khola Thrust, several imbricate thrusts, and two prominent NW-SE trending synclines: the Simruth Syncline and Syalpakha Syncline. Small-scale structures include bedding, cross bedding, mud cracks, ripple marks, stromatolites, foliation, small-scale folds, joints, boudins, and tension gashes. Small-scale folds trend along the WNW-ESE direction as like those of the major folds. Microstructures such as syntectonic garnet porphyroblasts, sutured grain contacts in quartzites, triple junctions in polygonized quartz, quartz ribbon structures, and crenulation folds in the schists of the Kuchibang Formation indicate multiple phases of deformation in the Main Central Thrust zone. Overall, this study seeks insights into the regional tectonic evolution and the geological history of the western Nepal Lesser Himalaya.