Culmination Collapse in Fanjah Saddle, Oman: ABSTRACT

Abstract

Culmination collapse structures in the central Oman Mountains have overprinted and clouded the surface expression of deep-seated regional structures, as typified by the Fanjah Saddle. The saddle forms a domain of low structural relief situated along the trend of a series of major structural culminations. It is bounded on the east and west by the plunging noses of the parautochthonous Mesozoic shelf carbonates of the Saih Hatat and Jabal Nakhl culminations, respectively, and contains a stack of Late Cretaceous basinal and ophiolitic thrust sheets. Culmination collapse, initiated by backslip movement of the dense overlying nappes, has resulted in a saddle geometry containing both extensional and compressional regimes. Listric normal faults in the culminations converge toward the saddle and serve as feeder zones to the saddle core which acts as a sink for the thrust sheets. Smaller surge zones with extensional trailing edges and compressional fronts defined by recumbent folds radiate outward from the culminations. This has been superimposed over earlier isoclinal folding produced by the emplacement of the overlying nappes. The final result is a complex internal geometry and distribution pattern of structures. Distinguishing these shallow deformational events from deep seated structural styles is essential for the correct extrapol tion of surface data to the subsurface in any exploration program. End_of_Article - Last_Page 463------------