Second Projet de Renforcement Institutionnel du Secteur Minier de la Republique Islamique de Mauritanie (prism-ii)
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| BIF’s produce short (10’s of km) narrow wavy high amplitude (>500 nT-3000nT) positive magnetic anomalies (Fig. 22). The BIF's act as structural markers within deformed non-magnetic greenstone belts. They can be differentiated from all other anomaly sources by the very high amplitudes of the anomalies that they produce. The broad, high amplitude anomalies in the center correspond to the Paleoproterozoic Kediat Ijil complex whose susceptibilities range from 0.027 x 10-3 SI in the hematites to 570 x 10-3 SI in the magnetite bearing units (Compex d’Ijil, Excel spread sheet; O’Connor et al., 2005). In addition, the Kediat Ijil is associated with low concentrations of radioelements (Figs. 12-15). The longer wavelength anomalies in the SE portion of the map correspond to BIF’s beneath the Taoudeni Basin. The gneissic and granitic basement are magnetically quiet, with susceptibilities <~50 x 10-3 SI (Excel spread sheet (O’Connor, Pitfield et al. 2005). Calculated maximum depths to the top of magnetic basement in this region (Fig. 11, Plate 3) is less than ~1000 m.
Figure 23. Close-up of crystalline basement map over Triassic-Jurassic sills and volcanic rocks at the western border of the Taoudeni Basin (box 23, Fig. 17, Plates 1 and 2). 
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