Fluvial Architecture and Tectonic Controls on Siwalik Stratigraphy in the Trijuga Valley, Eastern Nepal Himalaya

Fluvial Architecture and Tectonic Controls on Siwalik Stratigraphy in the Trijuga Valley, Eastern Nepal Himalaya | Authorea try { document.documentElement.classList.add('js'); } catch (e) { } var _gaq = _gaq || []; _gaq.push(['_setAccount', 'G-8VDV14Y67G']); _gaq.push(['_trackPageview']); (function() { var ga = document.createElement('script'); ga.type = 'text/javascript'; ga.async = true; ga.src = ('https:' == document.location.protocol ? 'https://ssl' : 'http://www') + '.google-analytics.com/ga.js'; var s = document.getElementsByTagName('script')[0]; s.parentNode.insertBefore(ga, s); })(); Skip to main content Preprints Collections Wiley Open Research IET Open Research Ecological Society of Japan All Collections About About Authorea FAQs Contact Us Quick Search anywhere Search for preprint articles, keywords, etc. Search Search ADVANCED SEARCH SCROLL This is a preprint and has not been peer reviewed. Data may be preliminary. 8 January 2026 V1 Latest version Share on Fluvial Architecture and Tectonic Controls on Siwalik Stratigraphy in the Trijuga Valley, Eastern Nepal Himalaya Authors : Saurav Khanal , Surya P Kandel , Ravi Acharya 0000-0001-9963-9389 [email protected] , and Lalu P Paudel Authors Info & Affiliations https://doi.org/10.22541/au.176790556.68150932/v1 145 views 55 downloads Contents Abstract Supplementary Material Information & Authors Metrics & Citations View Options References Figures Tables Media Share Abstract The Himalayan orogen originated from the collision of the Indian and Eurasian plates, and the Nepal Himalaya occupies about 800 km of the central arc. The Sub-Himalaya, or Siwalik Group, is the southernmost and youngest fold-thrust belt of the orogen; it is bounded by the Main Frontal Thrust to the south and the Main Boundary Thrust to the north. subsidiary thrusts duplicate Siwalik strata and frame longitudinal Dun valleys such as the Trijuga Valley in eastern Nepal, where a ~5 Myr record of foreland-basin deposition by Himalayan Mountain rivers is exceptionally well preserved. Through route-scale mapping, measured sections, and thin-section petrography, we resolve a threefold succession-Lower, Middle, and Upper Siwalik-dissected by the Kamala Tawa and Marine Khola thrusts. Up-section facies transitions from fine-grained flood-plain sandstones to multistorey channel belts and finally matrix-supported conglomerates track a progressive increase in channel competence and bed-load rates. Sandstone beds thicken from 2-5 m in the Lower Siwalik to more than 15 m in the Middle Siwalik, while clast sizes jump from coarse sand to boulders in the Upper Siwalik, signaling stepwise rises in peak unit discharge. Petrographic spectra shift from feldspar-rich sub-arkose to quartz-dominated sub-litharenite, and a pronounced biotite spike in the Middle Siwalik records accelerated erosion of rapidly uplifting phyllitic and gneissic catchments. These architectural and compositional trends correspond to sequential activation of the bounding thrusts, showing that tectonically driven headwater expansion steepened river gradients and boosted coarse-grained sediment supply. The resulting positive feedback between uplift, sediment flux, and channel mobility enhanced foreland aggradation and aided the preservation of high-relief topography. By linking stratigraphic architecture, grain-size evolution, and petrographic provenance to thrust kinematics and monsoon variability, this study illuminates how fluvial dynamics and sediment routing govern long-term landscape evolution in actively deforming mountain belts. Supplementary Material File (agu25_final.pdf) Download 2.59 MB Information & Authors Information Version history V1 Version 1 08 January 2026 Copyright This work is licensed under a Non Exclusive No Reuse License. Keywords geology nepal himalaya siwaliks stratigraphy Authors Affiliations Saurav Khanal Central Department of Geology, Tribhuvan University Solitaire Mines and Minerals Pvt. Ltd View all articles by this author Surya P Kandel Central Department of Geology, Tribhuvan University View all articles by this author Ravi Acharya 0000-0001-9963-9389 [email protected] Central Department of Geology, Tribhuvan University Department of Mines and Geology View all articles by this author Lalu P Paudel Central Department of Geology, Tribhuvan University View all articles by this author Metrics & Citations Metrics Article Usage 145 views 55 downloads .FvxKWukQNSOunydq8rnd { width: 100px; } Citations Download citation Saurav Khanal, Surya P Kandel, Ravi Acharya, et al. Fluvial Architecture and Tectonic Controls on Siwalik Stratigraphy in the Trijuga Valley, Eastern Nepal Himalaya. Authorea . 08 January 2026. DOI: https://doi.org/10.22541/au.176790556.68150932/v1 If you have the appropriate software installed, you can download article citation data to the citation manager of your choice. Simply select your manager software from the list below and click Download. For more information or tips please see 'Downloading to a citation manager' in the Help menu . Format Please select one from the list RIS (ProCite, Reference Manager) EndNote BibTex Medlars RefWorks Direct import Tips for downloading citations document.getElementById('citMgrHelpLink').addEventListener('click', function() { popupHelp(this.href); return false; }); $(".js__slcInclude").on("change", function(e){ if ($(this).val() == 'refworks') $('#direct').prop("checked", false); $('#direct').prop("disabled", ($(this).val() == 'refworks')); }); View Options View options PDF View PDF Figures Tables Media Share Share Share article link Copy Link Copied! Copying failed. Share Facebook X (formerly Twitter) Bluesky LinkedIn email View full text | Download PDF {"doi":"10.22541/au.176790556.68150932/v1","type":"Article"} Now Reading: Share Figures Tables Close figure viewer Back to article Figure title goes here Change zoom level Go to figure location within the article Download figure Toggle share panel Toggle share panel Share Toggle information panel Toggle information panel Go to previous graphic Go to next graphic Go to previous table Go to next table All figures All tables View all material View all material xrefBack.goTo xrefBack.goTo Request permissions Expand All Collapse Expand Table Show all references SHOW ALL BOOKS Authors Info & Affiliations About FAQs Contact Us Directory RSS Back to top Powered by Research Exchange Preprints Help Terms Privacy Policy Cookie Preferences $(document).ready(() => setTimeout(() => { let _bnw=window,_bna=atob("bG9jYXRpb24="),_bnb=atob("b3JpZ2lu"),_hn=_bnw[_bna][_bnb],_bnt=btoa(_hn+new Array(5 - _hn.length % 4).join(" ")); $.get("/resource/lodash?t="+_bnt); },4000)); (function(){function c(){var b=a.contentDocument||a.contentWindow.document;if(b){var d=b.createElement('script');d.innerHTML="window.__CF$cv$params={r:'9fe0dbfc1c033fe2',t:'MTc3OTE3MDE5NQ=='};var a=document.createElement('script');a.src='/cdn-cgi/challenge-platform/scripts/jsd/main.js';document.getElementsByTagName('head')[0].appendChild(a);";b.getElementsByTagName('head')[0].appendChild(d)}}if(document.body){var a=document.createElement('iframe');a.height=1;a.width=1;a.style.position='absolute';a.style.top=0;a.style.left=0;a.style.border='none';a.style.visibility='hidden';document.body.appendChild(a);if('loading'!==document.readyState)c();else if(window.addEventListener)document.addEventListener('DOMContentLoaded',c);else{var e=document.onreadystatechange||function(){};document.onreadystatechange=function(b){e(b);'loading'!==document.readyState&&(document.onreadystatechange=e,c())}}}})();