Geology and structure of the north-west portion of the Cambrai Sheet.

Abstract

The geological history of the area is interpreted as follows. Deposition of the Saunders Creek Formation under shallow water marine conditions from a stable land mass. Deposition of the Pine Hut Formation and Eden Valley Formation under shallow water marine conditions with an unstable land mass, possibly due to an uplift. Deep burial under later sediments not revealed in the area. East-west compression resulting in tight folding, followed by axial plane faulting giving rise to the East Limb Fault and Somme River Shear. Intrusion of the dolerites, contemporaneous with or followed by granitisation and development of quartz blows. Uplift above sea level followed by a long erosional period resulting in a peneplaned surface. Deposition of the Tertiary shallow fresh water sediments and the formation of the residual deposits. Early Tertiary block faulting resulting in the formation of the Murray Range Fault. Deposition of the later Tertiary limestones of the Murray Plains with erosion of the uplifted block. Uplift of the whole area with recession of the Murravian Gulf. Deposition of recent deposits and erosion giving the present topography.