ODP Leg 208: Early Cenozoic Extreme Climates: the Walvis Ridge Transect

Figure 12

Wavelet Transform (modulus) of density (RHOM), porosity (APLC), total gamma ray (HSGR), medium resistivity (IMPH) and surface resistivity (SFLU) between 110 and 270 mbsf at Hole 1263A. Vertical axis: logging depth (linear scale, mbsf); horizontal axis: scale (log2 scale, m). Red: high modulus, blue: low modulus. Thin solid lines indicate interval of statistically significant modulus. Thick solid line indicates zone where edge effects become important. Thin dashed lines mark the main cycles around 4, 11, 15 and 25 m. The density (RHOM), anti-correlated with the porosity (APLC), shows much smaller fluctuations than the cycles about 30 m, 15 m and 10 m. The porosity (APLC) and the gamma ray (HSGR) logs both show cyclicity down to the sub-meter scale. Resistivity (medium: IMPH and shallow; SFLU) cycles are similar to density cycles, but with a greater detail. The changes in the spatial distribution of these localized cycles conform with, and thus reinforce the previously defined unit sub-division (note the change in the pattern of the Wavelet Transform representation around 170 mbsf).