U. Suzuki, 1983. "The Volcanic Mound", Seismic Expression of Structural Styles: A Picture and Work Atlas. Volume 1–The Layered Earth, Volume 2–Tectonics Of Extensional Provinces, & Volume 3–Tectonics Of Compressional Provinces, A. W. Bally
Download citation file:
This volcanic mound is a circular or cone-shaped feature situated in the Sea of Japan, a backarc basin. The slopes of the anomaly on the seismic time section measure about 160 and regional paleoecological data suggest the enclosing lithologies are of deepwater origin. Some seismic reflections within the feature mimic the external shape suggesting buildup by successive addition of material from the central part through sedimentary processes.
It was confirmed by drilling that the round was a convex volcanic body which consists of basaltic lavas, basaltic to andesitic tuffs, and lavas with multiple dolerite intrusions.
The volcanic mound appears to have formed during middle Miocene, and several similar volcanic features can be seen in addition to the one shown. Generally, the volcanic mounds rest on the "Green Tuff Platform" of which genesis appears to be related to the horst-graben activity (the initiation of the Sea of Japan) during Paleogene to early Miocene (Suzuki, 1979; see paleogeographic map).
In some cases, such volcanic mounds are preferred sites for hydrocarbon accumulations, such as the Mitsuke oil field, and the Yoshii and Katagai gas fields onshore in Japan (Kujiraoka, 1980).