Journal - The Lower Siwalik - Basement unconformity in the Sub-Himalaya of eastern Nepal and its significance

The Lower Siwalik - Basement unconformity in the Sub-Himalaya of eastern Nepal and its significance

Rajendra Bahadur Shrestha and Shardesh Raj Sharma

Petroleum Exploration Promotion Project, Department of Mines and Geology

Lainchaur, Kathmandu, Nepal

Jour. Nep. Geol. Soc., Vol. 13, 1996, 29-36


South of the Main Boundary Thrust (MBT), in the Sub-Himalaya of central and eastern Nepal, pre-Siwalik rocks in the form of fault bound slices are known to occur. Recently the present authors have mapped these rocks in the Udayapur district of south eastern Nepal. In the area about 1 km wide pre-Siwalik rocks extend for over 50 km along a NE-SW direction. In the eastern area around Tintale village (near the Tawa Khola-Baijanath Khola confluence), the stromatolitic dolomites of Tintale Formation of the pre-Siwalik Group is overlain by the Lower Siwalik with a prominent unconformity marked by a 4.5 m thick basal conglomerate. Likewise, in the western area along the Manba Khola, the Siwalik Group overlies the pink sandstones and shales of the Manba Formation of the pre-Siwalik Group with an unconformity, again with a conglomerate horizon at the base. It is perhaps the only occurrence where the base of the Siwalik Group is recorded in Nepal. In this part of the Himalaya, the Siwalik sediments directly overlie the Precambrian-Lower Paleozoic (?) basement rocks with an unconformity. The basement rocks along with its Siwalik cover was brought to the surface by thrusting within the Sub-Himalaya.

Member Login
  • Jul

    Academic and professional development Sub Committee of the Nepal Geological Society and Nepal Geological Students’ Society in collaboration with Central Department of Geology has organized a training and interaction program entitled “Mining and Engineering Geology in field” on 23rd  Asadh 2075 at the conference hall of the Central Department of Geology, Kirtipur.

  • May

    Nepal Geological Society has organized a press meeting on the memory of 2015 Gorkha Earthquake on 2075/1/12 at the conference hall of Department of Irrigation, Jawalakhel

Activities and Information

Activities of 17th and 18th Executive Committee
Nepal Geological Society
P.O.Box No. 231
Kathmandu, Nepal
FREEPHONE: +977-01-4437874