Chromite Geology

The dominate feature of the geology of Northern Oman is the Samail Ophiolite sequence. The Samail Ophiolite Nappe of Northern Oman was abducted at the close of the Tethyan Ocean during the Upper Cretaceous period approximately 90 million years ago. The sequence consists of a suite of oceanic and mantle related lithologies and occurs as the mountainous region in Northern Oman. The sequence is host to a number of mineral deposits including chromite.

The Oman Chromite deposits of significance have two main modes of occurrence within rocks of the Samail Ophiolite namely:

• As small bodies concentrated within the uppermost 1.5 km of the Mantle Sequence, just below the base of the Cumulate Sequence; and

• As large, less abundant bodies scattered within the deeper levels of the Mantle Sequence.

Lithologies found in association with the chromites are Mantle Sequence and Cumulate Sequence rocks. The Mantle sequence consists of two main rock types: harzburgite and dunite. The Cumulate Sequence represents the lowest part of the mid-ocean ridge, consisting of ultramafic cumulates and gabbro cumulates. The chromite deposits are confined to the Mantle Sequence and the ultramafic cumulates.

The chroimte deposits range in form from tabular or lenticular when least deformed, to podiform when most deformed. Most of the bodies strike parallel to regional structures in the Mantle Sequence rocks.