Reflection Profiles Across the Aquitaine Basin (Salt Tectonics)
Published:January 01, 1983
R. Curnelle, R. Marco, 1983. "Reflection Profiles Across the Aquitaine Basin (Salt Tectonics)", 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 profile (Figures 2a, 2b) shows three halokinetic (Triassic salt) structures in different stages of theirs evolution:
To the north a structure which grew during the Cretaceous as indicated by the thinning of the corresponding beds. Erosion at the base of the Tertiary suggests later reactivation of the salt structure.
To the south a pre-Oligocene piercement structure.
in the center of the section an exaggerated piercement which almost reaches the present sea floor.
Sedimentation during the Albo-Aptian involves thickening of the beds in synclines between salt swells.
This profile (Figures 3a, 3b) shows the following features:
Outflow of salt during the Eocene.
The "roots" of the structure are related to a deep structural feature causing doming during the Albe-Aptian extensional phase.
The Pyreneen compressional phase was very active during the Eocene and leads to the outflow of the salt.
The roof of the salt dome carries a Senonian fragment that was encountered by Well B but not penetrated in Well A.
The doming of the salt seemingly affects the northern flank of the section with thickening of the beds during the Eocene. Synclinal compensatory filling during the Eocene is also associated with the southern flank.
Halokinetic processes ceased during the Miocene and Pliocene. This period corresponds to the east to west progradation of the continental shelf as indicated by a number of channels displayed on the section.
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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.