Figure F5. A. Deep-towed sidescan sonar imagery across Hydrate Ridge. High backscatter sites (light tones), which were groundtruthed by seafloor observations and sampling, represent sites of seafloor or shallow subseafloor authigenic carbonate locations (Johnson et al., 2003). B. The same region with sidescan data removed to emphasize the greater abundance of authigenic carbonates (high backscatter sites outlined in black) on northern Hydrate Ridge (NHR) compared to southern Hydrate Ridge (SHR). The approximate extent of the older (>1.7–1.6 Ma) stratigraphy exposed at or near the seafloor at NHR is shown as gray overlay and is coincident with the region of most intense authigenic carbonate precipitation. This is in contrast to SHR, which has limited authigenic carbonate occurrences and is capped by younger (from <1.7–1.6 Ma to recent) slope basin stratigraphy.

Figure F5. A. Deep-towed sidescan sonar imagery across Hydrate Ridge. High backscatter sites (light tones), which were groundtruthed by seafloor observations and sampling, represent sites of seafloor or shallow subseafloor authigenic carbonate locations (Johnson et al., 2003). B. The same region with sidescan data removed to emphasize the greater abundance of authigenic carbonates (high backscatter sites outlined in black) on northern Hydrate Ridge (NHR) compared to southern Hydrate Ridge (SHR). The approximate extent of the older (>1.7–1.6 Ma) stratigraphy exposed at or near the seafloor at NHR is shown as gray overlay and is coincident with the region of most intense authigenic carbonate precipitation. This is in contrast to SHR, which has limited authigenic carbonate occurrences and is capped by younger (from <1.7–1.6 Ma to recent) slope basin stratigraphy.