Discovery of heavy mineral sand in Djiboutian coastline (Obock area, SE Afar rift)

Abstract

Background

In this paper, we present the first study of black sand deposits collected along the coastline of the Obock area, which is located in the North East part of Djibouti (SE Afar Rif). This area consists mainly of uplifted madrepores, sand dunes and alluvial deposits.

Materials and Methods

Geochemical studies were carried out using techniques such as X-ray fluorescence (XRF) to quantify the heavy mineral sands. Electron microprobe and X-ray diffraction (XRD) techniques were used to identify minerals.

Results

Mineral sands have been identified in coastal backshore deposits, containing light minerals (calcite, aragonite, quartz, anorthite, augite, microcline, albite, enstatite, nontronite and diopside) and heavy minerals (hematite, ilmenite, chromite and magnetite). In general, titanium dioxide (TiO₂) and iron oxide (Fe₂O₃) are found in the backshore, with averages of TiO₂ (23.9 %) and Fe₂O₃ (53.9 %) in the total of heavy mineral fraction.

Conclusions

Although, titanomagnetite is not widely exploited in the world due of the treatment to enrich ores with Fe and Ti, the presence of ilmenite and vanadium as trace elements in the subsurface and in titanomagnetite respectively, even at very low grades may potentially justify further of the lateral extent and depth geochemical and drilling investigations in order to upgrade the concentration of titanium oxide in the Obock coastal sands.