@article{oai:soar-ir.repo.nii.ac.jp:00012001, author = {REGUMI, Amar, Deep and DHITAL, Megh, Raj and GADTAULA, Rishi and TAMRAKAR, Naresh, Kaji and YOSHIDA, Kohki}, journal = {Journal of the Faculty of Science Shinshu University}, month = {Mar}, note = {Late Cainozoic fluvial sedimentary sequences of the Siwalik Group is extensively accumulated in the southern frontal part of the Himalaya and well exposed along southern part of Dang and in all sides of the Deukahari Valley of west-central Nepal Himalaya.Lithostratigraphy of the succession consists of the Bankas Formation, Chor Khola Formation, Suria Khola Formation, Dobata Formation,and the Dhan Khola Formation in an ascending order.The Bankas Formation is represented by an interbedding of red-purple mudstones, shales, and fine-to very fine-grained sandstones. The Chor Khola Formation shows a gradual increase of sandstone grain size as well as thickness of beds. The sandstones are calcareous and rich in plant fossils. The mudstones are variegated in the lower part and gray-green in the upper part. The Surai Khola Formation is mainly represented by multi-storied, coarse-to very coarse-grained ‘salt and pepper’sandstones.The beds yield a great amount of petrified wood in the form of steams, branches, and roots. The Dobata Formation is predominated by mudstones with a minor amount of sandstones and conglomerates.The Dhan Khola Formation comprises compact and hard boulder-and pebble-bearing conglomerates with yellow mudstones in the lower part and not well cemented conglomerates with yellow mudstones in the upper part.The sandstones of the study area mostly belong to the litharenite and subordinately to the sub-litharenite.The rocks show coarsening-upward succession in general but many fining-upward fluvial successions on a scale from several to tens of meters is established in each lithological unit. The Siwalik rocks show a coarsening-upwards sequence, evidencing a continuous uplift of the Himalayas. However, the individual depositional units show a detailed lithostratigraphic study and geological mapping of the area show that the rocks of the present study area are lithostratigraphically similar to those of the Surai Khola area located in the east of the study area. The rocks distributed in the study area are highly deformed. The persistence of shortening between Indian Plate and Asian Plate involves their deformation. This deformation is expressed in the form of faults and folds which succeed one another in both space and time.The study area is subjected to more than one phase of deformational process.Series of faults such as the Bheri Thrust, Mali Khola Thrust, Babai Back Thrust, Tui Khola Back Thrust, and Rapti Back Thrust and also a number of folds as Baijapur Anticline, Bhaisahi Anticline, Khairi Khola Anticline, and Malai Khola Anticline, Agaiya Syncline, Satbariya Syncline, and Masot Khola Syncline delineate the study area. The pattern of thrusting here is related to the thin-skin tectonic model. The thrusts show the ramp-flat geometry and the thrusting is related to the piggy-back propagation pattern. Due to this thrusting the rocks here are repeated more than five times.The Dang Valley is located in a triangle zone bounded by the thrusts, which seems to be generated by retardation of faulting, thrusting and folding., Article, Journal of the Faculty of Science Shinshu University 43: 1-42(2011)}, pages = {1--42}, title = {Lithostratigraphy and structures of the Siwaliks rocks in the southern part of Dang and its surrounding area, Southwestern Nepal}, volume = {43}, year = {2011} }