MORPHOTECTONIC EVOLUTION OF THE LATERITE PROFILES OVER SUKINDA ULTRAMAFICS, JAJPUR DISTRICT, ORISSA

Sukinda ultramafic field of Jajpur district, Orissa is capped by thick lateritic duricrust. Two generations of laterite are inferred in the studied area. The older laterite (in situ) is capped by transported la terite (younger). The entire area is divided into two sub areas (A(1) and A(2)). Physiographically, three terraces are identified in A(1) ar ea, of which, the oldest one (T-3) comprises of insitu lateritic hard crust. The other two terraces (T-2 and T-1) are made up of valley fill deposits, which are later lateritised. The area A(2) shows the latera l continuity of T-3 terrace of A(1) area along with valley fill deposi t of T-1 terrace and the absence of T-2 terrace. Drainage analysis sho w the A(1) area is structurally more disturbed than A(1) area. Correla tion of geomorphological evolution and lateritisation indicates three stages of development in the A(1) area. Lateritisation was initiated o n a comparatively flat ground (T-3 terrace) and subsequent destabilisa tion of the area developed the younger terraces (T-2 and T-1) with the modification of older laterite profile.