Iron–titanium sands of the Atlantic beaches between Tan-Tan and Tarfaya (southwest Morocco): Characterisation and origin

Abstract

In Morocco, the most important placers of ferrotitanium minerals are found along the Laâouina–Cape Juby Atlantic coastline, where they accumulate in the upper parts of the foreshores. The heavy minerals would come from the dismantling of the acidic to intermediate magmatic rocks of the Precambrian Anti-Atlasic buttonholes and from the Meseta basement where crystallophyllous rocks predominate. The sands emanating from this erosion, once ejected by the rivers in the Atlantic, are transported by the littoral drift in the direction of the south before being trapped at the level of the great virgation of the shoreline of Laâouina–Cape Juby. The wind deflation, in its turn, reinforces this sorting by carrying away the white sands towards the continent and also the black sands sometimes. The cliffs along the coast of Laâouina–Sidi Akhfenir are, however, barriers against wind loss unlike the sector of Sidi-Akhfenir–Cape Juby where the continuous migration of sands to the hinterland is facilitated by the absence of cliffs. The conjunction of these factors has the consequence of weakening the retention of sands' ferrotitanium in the sector Sidi Akhfenir–Cape Juby compared with its counterpart of Laâouina–Sidi Akhfenir. In general, the Laâouina–Cape Juby coastline can be considered a morphological and hydrodynamic trap whose concentrations in ferrotitanium minerals are likely to earn the quality of a mining district despite its seasonal instability and the difficulty of estimating reserves. Indeed, in this supposed district, heavy minerals total about 95 % of the raw sediments and ilmenite predominates and its alteration state is only superficial.