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Geology researchers are concerned with studying the layers of ophiolites in order to understand the history of the geographical and natural space that includes them. The latter are part of the surrounding crust of the Earth, located on the rocks of the continental crust as a result of their displacement due to tectonic movements and integration with mountains.

Exploring new mineral resources, such as chromite and copper deposits, within the Masirah ophiolite is essential and requires detailed subsurface geophysical exploration to estimate their extensions and reserves. Finding the origin of chromite and the host mantle rocks will enhance the mechanism of ophiolite chromite formation, especially in terms of the origin of these deeply derived minerals and the thermal convection of the mantle.

As such, a study was conducted by Prof. Sobhi Nasir – Earth Sciences Research Centre – to investigate newly discovered chromite and gossan deposits and evaluate their economic value. Many gossan iron hydroxide and chromitite deposits were recently discovered in the Masirah Island ophiolite and the Batin area mixture east of Oman, through geological exploration and ophiolite mapping operations in eastern Oman. This is the first record of lenticular deposits in the Batinah ophiolite mixture. Many gossan rock deposits were also discovered on Masirah Island.

According to the study’s findings, the chromite rocks in Wadi Musawa in the Al-Batinah region have the shape of small lenses, ranging in thickness from 3-10 metres, and are characterised by a high concentration of chromium oxide at a rate of 45-50%, which makes mining economically feasible. Geochemical and petroleum analyses indicate that these deposits are of the lenticular type, and contain reddish-brown chromite grains, which partially transform into black chromite. The results also show that they were formed in the mantle region due to the partial melting of shallow mantle peridotite. The surface chromite reserve in Wadi Musawa is estimated to be about 20,000 tons, while the small chromite lenses in the Dunit of Masirah Island have no economic value.

Exploration and mapping operations in the Masirah ophiolite rocks revealed the presence of gossan deposits within the basalt rock sequence. These deposits included highly thermally and hydrothermally oxidised zones, and contained multiple minerals, including hematite, limonite, goethite, chlorite, epidote, calcite, kaolin, sercite and illite. Sample laboratory analysis showed that they were formed in the environment of the central Indian Ocean, with high concentrations of transition and rare earth elements, while high concentrations of copper were observed in the oxidation and phyllic zones.

The study’s recommendations include carrying out drilling operations in Wadi Musawa to better determine the subsurface extensions and reserves of chromite deposits as a means of enhancing the utilisation of these resources, and encouraging the mining of chromite deposits in Wadi Musawa due to the high concentration of chromium oxide. However, mining small chromite lenses in the Dunit of Masirah Island is economically infeasible. The researcher also suggested that a comprehensive geophysical survey in the gossan areas of Masirah Island be made in order to estimate the reserves of copper and other economically feasible elements, especially in the oxidised and phyllic areas, as this may contribute to developing the mining sector locally.

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Prof. Sobhi Nasir – Earth Sciences Research Centre