Structural pattern deduced from aeromagnetic dataover parts of Nasarawa and environs Northcentral Nigeria.

Abstract

Interpretation of high-resolution aeromagnetic data over Nasarawa area was carried out to observe near surface source magnetic features that are associated with geological structures in the study area, Prominent lineaments in this study may be related to fractures that were not revealed by previous studies. Some of these lineaments coincide with concealed faults and fractures at Akiri warm spring and vicinity. Because this area has known warm springs, faults or fault intersections at depth can lead to upward movement of warm water that enhances permeability. Thus, mapping concealed fractures provides a focus for follow-up geothermal studies. Fault interpretation was accomplished by synthesizing interpretative maps derived from first vertical derivative and analytical signal along with preliminary depth estimates. Faults were interpreted along linear aeromagnetic anomalies and breaks in anomaly patterns. Many linear features correspond to topographic features, such as drainages. A few of these are inferred to be fault-related. The interpreted faults show criss-crossing pattern of fault zones, some of which appear to step over where they cross, and show zones of west-northwest, north-, and northwest-striking faults that cross west-northwest around Akiri warm spring. North easterly striking faults extend east from this juncture. The associated aeromagnetic anomalies are likely caused by magnetic contrasts associated with rifting of crust beneath the Benue Trough.

KEY WORDS: Derivative, Structural Pattern, Rift Zones, Akiri.