Petrobras, 1983. "Acre and Upper Amazon Basins, Brazil", 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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Seismic data were digitally recorded with 6-fold coverage, 24-channel equipment, source was shallow shaped charges and an off-end configuration with maximum offset of 2,900 m (9,514 ft) (15 charges of 3 kg per shotpoint), and the geophone array was 69 m (226 ft) long with 24 equi-spaced elements.
UPPER AMAZON BASIN
This seismic line is located in the Upper Amazon Paleozoic Basin (Jurua Area) and its orientation is northwest to southeast. The line crosses an expressive northeast to southwest structural trend developed in the central part of the basin.
The reflectors highlighted on the seismic section represent, from top to bottom:
— the top of the Cretaceous section (1);
— the pre-Cretaceous unconformity (2);
— the top of the Carboniferous section (3); and,
— the unconformity between the Permo-Carboniferous and Devonian sections (4).
The Permo-Carboniferous section is intruded by Juro-Triassic diabase sills.
The folding and reverse faulting of the Paleozoic rocks and of the Mesozoic intrusives, is presently being interpreted as the result of compressive efforts that were active in Neo-Jurassic - Eo-Cretaceous time.
The folded and faulted sections are truncated by a regional unconformity over which lies a Cretaceous sandy section.
Figures & Tables
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.