Fabric development and emplacement mechanism of the Cenozoic Fossong-Wentcheng trachytic dome (Mount Bambouto, West Cameroon): an integrated AMS investigation.

Of Cenozoic age, the Fossong-Wentcheng trachytic dome is located on the southwestern slope of Mount Bambouto. It was probably emplaced during the second period of activity (between 18.5 and 15.3 Ma) of the Mount Bambouto, within the Pan-African granitic basement rock. The dome shows aphyric and porphyritic textures with crystals such as sanidine, clinopyroxene, and oxides. These oxides may be magnetite due to the dominant ferromagnetic behavior of the rock. The dominance of planar AMS ellipsoids and low P_j values reflect the high viscosity of the magma that sets up the Fossong-Wentcheng trachytic dome. The magnetic fabric (foliation and lineation) displays roughly sub-circular trends in the central and the northern parts of the dome with the feeder zone located on its southern part where they display fabrics in the NE-SW direction with steep dips and plunges. This implies that the magma rose through a NE-SW–directed fracture in the basement granitic rock before its propagation towards the NNW-SSE direction by developing one lobe flow emplacement. [ABSTRACT FROM AUTHOR]