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An equivalent layer magnetization model obtained from inversion of long wavelength satellite magnetic anomaly data indicates a very magnetic source region centered in south central Kentucky. The magnetization maximum nearly coincides with a gravity high elongated north-south and extending into Tennessee. Previous refraction profiles suggest that the source of the gravity anomaly is a large mass of rock occupying much of the crustal thickness. The outline of the source delineated by gravity contours is also discernible in aeromagnetic anomaly patterns. Taken together, the geophysical data suggest a large, localized mass of intracrustal rock which is both dense and very magnetic. A simple magnetization/density model is given which accounts for the gravity and long wavelength aeromagnetic anomalies due to the body. We interpret it as a mafic plutonic complex, and several lines of evidence are consistent with a rift association. The body is, however, clearly related to the inferred position of the Grenville Front. It is bounded on the north by the fault zones of the 38th Parallel Lineament. The inferred mean magnetization (4 A/m) of the body is large, but not inconsistent with values reported by others for deep crustal bodies associated with long wavelength magnetic anomalies. Such magnetization levels can be ach'eved with :magnetic mineralogies produced by normal oxidation and.metamorph°c processes and enhanced by viscous build-up, especially in mafic rocks of alkaline character.
Vegetation patterns in the North Black River peatland, northern Minnesota
Raised bogs and water tracks in the 193-km2 North Black River peatland in northern Minnesota were examined in relation to the vegetation, water chemistry, and surficial water movements as inferred from infrared aerial photographs, LANDSAT imagery, and orthophoto topographic maps. Two noda of bog vegetation were distinguished by the Braun–Blanquet system; both bog noda are associated with relatively dilute, acidic waters (pH range 3.9–4.1; Ca2+ concentration range 0.6–1.6 mg L−1; specific conductivity, Kcorr range 1.3–83 μS cm−1). Rich-fen vegetation in contrast is more variable within this peatland and generally occurs in water tracks with a correspondingly wide range of pH (range 5.0–6.2), Ca2+ concentration (range 3.6–30.4 mg L−1), and Kcorr (range 31 to 182 μS cm−1). Poor-fen vegetation was most distinguishable by the transitional nature of its vegetation and water chemistry with at least a few minerotrophic indicator species present in all cases and intermediate ranges in pH (3.7–5.2), Ca2+ concentrat...
Archaeological Survey of Dangoyama Kofun by 3DGPR
We presented a three-dimensional ground penetrating radar (3DGPR) system for the archeological investigation in a harsh site, where we have to deal with many trees and/or great topographic variations. This system consists of a commercial GPR system with a laser positioning system. With this system, we can move the GPR antenna freely, on which a positioning detector can record accurate position for each GPR data trace. We applied our 3DGPR system at Dangoyama Kofun, a burial mound, in Fukushima prefecture, Japan. A lot of trees and bushes covered the survey area and cannot be cut. We acquired six datasets in two days in this area. We successfully imaged the boundary between the original surface of the burial mound and the covering soil clearly at about 0.3 m depth around the mound. Furthermore, we found some strong reflections appeared at 0.8 m depth in the top area of the mound, which can be from the artificial parts of the burial mound. The results would greatly aid the following archaeological excavation. In addition, we compared the non-interpolated depth slice with interpolated depth slice at same position and demonstrated that the interpolation process on threedimensional GPR data may introduce some artifacts which might mislead our interpretation.