Environmental mineralogy of unconsolidated surface sediments associated with the 2001 landslides on volcanic cones, Mabeta New Layout, Limbe, Cameroon

Abstract

Samples of unconsolidated surface sediments from the 2001 landslide occurrences in the Mabeta New Layout, Limbe, Cameroon were studied using sediment colour characterization as well as x-ray powder diffraction (XRPD) and optical microscopy (OM) techniques in order to ascertain mineral phases contained in them and postulate any influence the minerals may have had in triggering off the event. In terms of colour characterization, the hue/value/chroma of the sediments ranged from 5YR/5/3 to 5YR/4/6 to 5YR/3/4 with corresponding colour shades from reddish-brown to yellowish-red to dark reddish brown. Results of XRPD indicated that the samples consisted of the following mineral phases: anatase, annite, augite, goethite, hematite and kaolin, with the Fe-bearing minerals being dominant. Traces of maghemite were found in a few of the samples, and clinopyroxene was identified in the saprolite. The OM results confirmed those obtained for colour characterization and minerals identification. The findings of the study depict that hydrologic, tectonic and seismic factors combined with the physical properties of the mineral assemblages in triggering the landslides. These physical properties included the shapes and sizes of the mineral particles as well as mineral density.

Keywords: landslides, unconsolidated sediments, saprolite, x-ray diffraction

Global Journal of Environmental Sciences Vol. 4(2) 2005: 115–122