Geochemical Analysis as a Complementary Tool to Estimate the Uplift of Sediments Caused by Shallow Gas Hydrates in Mounds at the Seafloor of Joetsu Basin, Eastern Margin of the Japan Sea

Figure 8

Correlation of cores from background area (red diamonds) and mounds of both Umitaka Spur (black circles) and Joetsu Knoll (green squares). The graphs show the geochemical parameters versus age, obtained by core correlation. Geochemical signatures of sediments placed over mounds, associated to gas hydrates, are a mixture of both Holocene and LGM signatures, in spite of being located at the seafloor and where only Holocene sediments expected to occur. Purple squares and open diamonds represent samples collected from both piston and push cores located at mounds of Umitaka Spur, where gas hydrate occurs. They are plotted at the top in the absence of age data for these cores. Their signatures range from the LGM to the present, indicating a mixture on the surface of mounds.