Field Study of the Positive Flower Structures of the Gombe Inlier, Upper Benue Trough, Northeastern Nigeria

Abstract

Abstract The Gombe inlier can be considered as a geological microcosm of the Gongola basin as it vividly displays general stratigraphic and structural styles within a relatively small, easily accessible area. The Cretaceous lithostratigraphic sequence of the Gombe inlier has been affected by sinistral strike-slip faults; the Gombe and Wuro Ladde-Wurin Dole faults with a Benue and Gongola trend respectively. Detailed study of these two faults shows that the Gombe fault is older and synsedimentary fault movement started in at least the mid-Santonian. Precambrian basement upthrust along the Gombe Fault is likely to have initiated during the first of the two compressive events that affected the upper Benue trough; the mid-Santonian N - S to N 174° E compression. The Wuro Ladde - Wurin Dole fault is relatively younger because (1) it sinistrally truncates the Liji hill anticlines that occur at the northern end of Gombe hill, resulting in a NEE - SWW trend, and (2) the orientation of transpressional structures along this fault suggest they developed during the end-Cretaceous N 140° E to N 150° E compression. Well-preserved transpressional structures along these faults provide the structural geologist a rare field examples to study their 3-dimensional (3D) geometry and kinematic evolution; and also as an analog for interpreting seismic reflection data that images complex strike-slip structures in the sub-surface.