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
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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).
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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
Until a few decades ago, structural and regional geology were traditionally the preserve of field geologists. They usually mapped areas of outcropping deformed rocks and supplemented their work by laboratory studies of rock deformation and by theoretical work. Structural geology became tied to the geology of uplifts, folded belts, and underground mines, all of which were accessible to direct observation. Since World War II we have witnessed a tremendous development of geophysics in oceanography and in petroleum geology. Academic geophysicists in oceanography led their geological colleagues into modern plate tectonics and industry geophysicists developed reflection seismology into a superb structural mapping tool that penetrated the subsurface.
Today we are facing a situation where instruction and textbooks in structural geology are almost entirely dedicated to rock deformation, analytical techniques in detailed field geology and summaries of plate tectonics. Illustrations based on reflection seismic profiles are virtually absent in textbooks of structural geology. These texts illustrate only the parts of the proverbial elephant, together with some conjecture, but without ever offering a glimpse of the whole elephant.
Some of the reason cited for the relative scarcity of published reflection profiles are: 1) the confidentiality of exploration data; 2) difficulties in the photographic reduction and reproduction of seismic profiles for a book format; 3) the two-dimensional nature of vertical reflection profiles; and 4) the obvious distortions in reflection profiles that are typically recorded in time.
The AAPG leadership felt that it was time to attempt to correct the situation and to produce this picture and work atlas. The first volumes, of what may become a series of volumes, are addressing an audience that includes: petroleum geologists concerned with structural interpretations; exploration companies that provide in-house training; the AAPG continuing education program; and academic colleagues interested in updating their curricula in structural geology by inclusion of reflection profiles from the “real world” in their teaching.
The atlas is not meant to be a textbook in reflection seismology (instead we listed some at the end of this introduction) nor a text in structural and/or regional geology. Our intent is simply to provide a teaching tool.