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The density and orientation of lineaments have been mapped from Landsat imagery in a 30,000 km2 (11,583 mi2) area in central Kentucky and central Tennessee to determine whether known lower crustal intrusion is expressed on the surface through anomalous lineament patterns. A seismic refraction line through northern Tennessee and southern Kentucky indicates an anomalous region approximately 200 km (125 mi) long and 70 km (43 mi) wide where the upper crust is less than 10 km (32,808 ft) thick. The anomaly is coincident with a magnetic high seen on aeromagnetic surveys and with a Bouguer gravity high. Satellite magnetic surveys indicate a high in the general region of the anomaly. A basement core in the southern part of the anomaly is composed of peralka ine riebeckite syenite, a rock characteristic of a rift tectonic environment.
Lineaments were mapped as alignments of morphologic features such as streams, escarpments, mountain ranges, and tonal features on 1:500,000 scale multispectral scanner images of Bank 6. Winter scenes were chosen for a lower sun angle for better lineament mapping. The location of the anomaly was not revealed until lineament mapping was completed. Density and orientation of the mapped lineaments were then analyzed.
The following conclusions were reached from these data. (1) The lower crustal structure has no apparent expression through anomalous direction of lineaments over the structure. (2) The lower crustal structure is expressed on the surface through an increase in density of lineaments over the structure. (3) Aeromagnetic and satellite magnetic highs coincident with lineament density highs suggest correlation with deep crustal intrusive structures.
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