ODP logging contractor: Delaware Geological Survey

Hole: Oceanview

Leg: 174AX

Location: Sea Isle City, Dennis Township (New Jersey)

Elevation: 2.87 m

Latitude: 39 10' 43.826" N

Longitude: 74 43' 31.643" W

Logging date: October, 1999

Total penetration: 480.18 m

Total core recovered: 387.53 m (80.7 %)

Logging Runs

Logging string 1: Gamma Ray

Logging string 2: Gamma Ray-Resistivity-SP-Temperature

Logging string 3: Full Wave Sonic Tool

Logging string 4: Caliper

Logging string 5: Gamma Ray

On October 8 the first logging string (Gamma Ray) was run through the rods from land's surface to 342.4 m with sampling at 3.05 cm. Log quality was excellent as judged by the match between gamma-ray log kicks and lithologic changes. With the rods pulled, the second logging string was run from land' s surface to 342.3 m. Tools on the sonde included natural gamma ray, 16 and 64-in. normal resistivity, fluid resistivity, lateral resistivity, spontaneous potential, single point resistance, temperature, and delta temperature. A third logging string consisting of a full wave sonic tool (run to 342.3 m) was run next, followed by a fourth logging string (3-arm caliper), also run to 342.3 m. Logging operations were concluded on October 28, with a gamma ray log recorded through the rods.

Processing

Depth shift: No depth match between runs has been performed.

Gamma-ray processing. The Natural Gamma Ray logs recorded uphole on October 28 were smoothed in IgorTM using a 21-pt binomial function. Binomial smoothing convolves the data with a (discrete) triangular function. The values of this function are normalized coefficients derived from Pascal's triangle at a level equal to the Smoothing parameter. The coefficient is that of a binomial (a + b)N , where N is the smoothing parameter, normalized to preserve the signal amplitude. At the given sampling rate (1/10 ft) and with N = 21, the width of the filter function is 2 ft. The algorithm used is derived from Marchand and Marmet (1983).

In frequency domain binomial smoothing is a Gaussian filter that removes higher frequency signals that are random (i.e., 'noise'). This is illustrated (Figure below) by the frequency response of the binomial smoothing algorithm applied to the Ocean View logs. Frequency cuts are not sharp and the high frequency signal is reduced in amplitude but not completely removed. The benefit of this filter is that it is very smooth (i.e., there is no frequency "ringing"). Such are filters superior to the moving average smoothing because the latter are 'boxcars' in the frequency domain; such filters do not smooth in the frequency domain and thus simply reduce amplitude without removing high frequency noise. Binomial smoothing is similar to Gaussian convolution filtering used by Miller et al. (1987) to smooth and present Cenozoic stable isotopic record. Although more sophisticated means exist to remove noise from data sets (i.e., those that maintain the full amplitude and gain that are lost in binomial smoothing), the filtering that we used is simple, statistically valid, and visually pleasing.