TECTONO SEDIMENTARY EVOLUTION OF DEHRADUN FAN

Abstract

I .ocated w itliin the Shi val ik lbrclaiid basin in Garhwal I-li malaya. the Dchradun Valley lorms a synclinal 'nternion.anc Valley/piggyback basin. It is bounded along the south by the Shivalik range and along the north by the Mussoorie range. Along its northern niargin the Main Boundary Thrust (MAT) places the Precambrian rocks of the Lesser Himalayan (LH) sequence over the Shivalik Group of rocks. The southern margin of the Shivahik range is bounded by the Main Frontal Thrust (MET), local lv known as the Mohand Thrust, which is demarcated by the sudden topographic rise of this range over the recent alluvium of the plains. Major parts of the Deliradun Valley are covered by three fons. from west to east i.e. the Donga Fan. the Dehradun Fan and the Bhogpur Fan. l'ectonic activity along the MBT and probably the footwall inibricates and the paleochimate have played a signiflcani role in the evolution of the Dehradun Fan. The Ireser1t study aims to find out the implicafions of' neotectonic activity on the evolution of Dehradun Fan by carrying out detailed stratigraphic analysis and establishing absolute LLlminescence ages of the different siratigraphic units. Neotectonic activity has played an important role in the evolution of Deliradun Fan, by affecting the whole Can. The development of the fan is marked by different episodes of deposition for different lobes. Mappiiig of deformation features in the fan suggests both the M FT and the MAT are active at present