In and Around the Rift: Faults on the Nsukka Formation


ikpuankwu

Overview of the Ikpuankwu quarry section (photo taken at the entrance). The fault is to the left. 

The Anambra basin is known to be faulted in many places but coming across outcrop size examples for the purpose of teaching is rare. This outcrop is a must visit for any trip around the Anambra basin.

The photo is from a large outcrop exposure, the Ikpankwu sand quarry located just off the Enugu-Port Hacourt express way at Ihube (approaching Okigwe).

The outcrop is composed of bluish grey shales (at the bottom) passing to sandstones interbedded with mudstones and siltstones.

Notice the listric (curved) fault geometry, rotation of the units on the hanging wall (downthrown) block and the dragging and smearing of the clay units on the fault plane.

Also apart from the cliff exposure we see an extension of the fault plane marked by the jutxaposition of dark shales and sanstones with a thick band of ferruginized and sheared mudstone which marks the fault plane.

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