List of Figures
Figure 1: The Baltimore Canyon Trough is between the Carolina Trough to the south and Georges Bank Basin to the northeast. Bathymetry is denoted by dotted lines. Fracture zones (FZ) in medium solid lines, and the East Coast and Blake Spur magnetic anomalies by light lines, are from Klitgord and others (1988). Multichannel seismic lines, with CMP (common mid-point) numbers annotated, are shown by the heavy lines. Approximate area of salt lens is shown by the hatchured area. HOM 676 is the location of the well that penetrated salt.
Figure 2: Interpreted, amplitude-modulated display of wavelet-processed multichannel reflection data. Vertical scale is two-way traveltime in seconds. Boxes show areas enlarged for Figure 3.
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Line 2 at the northern end of the Baltimore Canyon Trough shows the negative-polarity lens at about 5.2 s (two-way traveltime) on the landward side of the Schlee Dome and about 5.8 s (two-way traveltime) on the seaward side.
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Line 6 in the middle Baltimore Canyon Trough shows the salt seaward of the hinge zone and stratigraphically below the reef structure.
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Line 10 at the south end of the Baltimore Canyon Trough shows the salt lens seaward of the complex hinge zone and overlying possible volcanic rocks.
Figure 3: True-amplitude-processed sections of profiles shown in Figure 2. These exemplify the anomalously high amplitude of the negative-polarity reflector. Vertical scale is two-way traveltime.
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Figure 3A
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Figure 3B
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Figure 3C
Figure 4: Plots of amplitude decrease with time for the three multichannel seismic lines. The plots are shown for two CMP's in each line -- one in the salt lens area and, for comparison, one away from the salt. Curves shown are the least-squares best fit of the amplitude into a power law (t**n, where t=two-way traveltime).
Figure 5: Amplitude versus offset analysis for Line 10 near CMP 4250. Reflection coefficient versus incident angle is plotted for both positive and negative reflection coefficients. Solid lines show least-squares fit solution. Note that reflection coefficient decreases with increasing offset.
Figure 6: Two-layer model for encasing medium above and salt layer as lower layer. Plot shows reflection coefficient versus incident angle with the S-wave velocity solutions.
Figure 7: Integrated seismic section for a portion of Line 10. This mimics the impedance log for a given frequency band. The low impedance of the anomalous zone is noted.
Figure 8: One-dimensional model for the anomaly using a 15-Hz Ricker wavelet and five possible layer thicknesses. Scale for time (vertical axis) and reflection coefficient amplitude (horizontal axis) is shown. The spike represents the reflection coefficient amplitude. The heavy solid line represents the total seismic response -- similar to what is observed on the seismic sections.
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