Mineral Chemistry of Wehrlite Xenoliths Hosted in Basalts from the SW of Hoss&amp;#233;r&amp;#233; Dammougalr&amp;#233; (Adamawa Plateau, Cameroon): Thermobarometric Implications

Isaac Bertrand Gbambié Mbowou,Ismaïla Ngounouno,Dagwaï Nguihdama,Fadimatou Ngounouno Yamgouot,Mama Ntoumbe,Abdel Aziz Youpoungam

doi:10.4236/ojg.2017.710098

Abstract

Wehrlite samples (size: ~4 cm) hosted in basaltic lavas from the SW of Hosséré Dammougalré are located in the western Adamawa Plateau. Porphyritic and allotriomorphic texture characterize respectively host Basalt and wehrlite xenoliths. The phenocrysts of olivine (Fo68−74), and Ti-magnetite are scattered in host basalt. Wehrlite xenoliths (~4 cm size) contain Cr-rich clinopyroxene (diopise-augite), olivine (Fo76−88) and chromiferous spinel. Equilibrium temperatures calculated from Fe/Mg exchange reaction for olivine/spinel vary between 944°C and 1102°C. The wehrlite olivine crystals with low Fo (vi and Aliv contents. The studied spinel-bearing wehrlite xenoliths represent probably the residual portions of the upper mantle, which are an important source of information about lithospheric composition and thermal evolution beneath the Adamawa Plateau.

Highlights

Wehrlite samples hosted in basaltic lavas from the SW of Hosséré Dammougalré are located in the western Adamawa Plateau
The studied spinelbearing wehrlite xenoliths represent probably the residual portions of the upper mantle, which are an important source of information about lithospheric composition and thermal evolution beneath the Adamawa Plateau
The contact between the host basalt and wehrlite xenoliths is materialized by the accumulation of small Fe-Ti oxides and plagioclase crystals or the tiny host basalt veins

Summary

Introduction

They are an important source of information about lithospheric composition and thermal evolution in mantle regions associated with alkaline volcanism [1]. In the Adamawa Plateau (Figure 1), previously ultramafic xenoliths data are from Dibi area ([2] [3]), Youkou maar [4], Ngao Voglar [5] and Hosséré Garba [6]. These ultramafic xenoliths studied are of dunite and lherzolite composition. This plateau presented as the horst, is situated to the north of the Congo Craton, as the result of the fold belt shearing, oriented WSW-ENE [8]

Objectives

Methods

Results

Conclusion