Figure 21. Close-up of crystalline basement map over the Archean (south)-Paleoproterozoic boundary (north) (box 21, Fig. 17, Plates 1 and 2).
A linear east-trending magnetic low characterizes the Zednes fault that marks the boundary between the Archean (south) and Paleoproterozoic rocks (north) (Fig. 21). Easterly anomaly trends associated with BIF’s in the south are truncated by the low associated with the fault. Linear anomalies crossing this boundary indicate younger dikes. BIF’s occur within the fault zone (Plates 1 and 2). Other faults in the region are also lows. Age relations can be determined by examination of anomaly relations. Calculated depths to the top of magnetic basement (Fig. 11, Plate 3) range from ~60-800 m.
Figure 22. Close-up of crystalline basement map over BIF’s in F’Derick (box 22, Fig. 17, Plates 1 and 2).
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