P.L. Inderwiesen, 1983. "Salt Anticline—East Texas Basin", 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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The seismic line depicting the salt anticline is located in Van Zandt County, Texas (Figure 1). The line is oriented in a northwest to southeast direction and is approximately 18.1 km (11.25 mi) long.
The structural deformation of Mesozoic and Tertiary sediments in the East Texas basin is caused by movement of the underlying Middle Jurassic salt. The East Texas basin is one of several grabens which developed in response to the Triassic rifting of the Gulf of Mexico (Kreitler, 1980; Jackson, 1981). The boundary of the East Texas basin is delineated by the Mexia-Talco Fault System to the north and west, by the Sabine Uplift to the east, and the Angelina-Caldwell flexure to the south which separates the embayment from the Gulf Coast basin (Figure 1; Collins et al, 1981; Wood and Guevara, 1981).
Initially the East Texas basin was partly restricted allowing the deposition of up to 2 km (1.2 mi) of salt (Kreitler, 1980). Subsequent subsidence of the basin combined with the rapid deposition of clastics in the Early Cretaceous (Seni and Kreitler, 1981) provided the differential loading required for salt movement (Trusheim, 1960). Consequently, both salt anticlines and salt domes were formed from the lateral and vertical migration of salt. Regionally the salt anticlines are found mainly on the outer edges of the basin while salt domes are located toward the middle of the basin where both the overburden and salt may have been the thickest (Wood, 1981).
Turtle-shaped anticlines are regionally found among salt domes and salt anticlines. The formation of these structures is summarized here from descriptions by Wood (1981) and Wood and Guevara (1981). Initially salt migrates away from an area of maximum deposition causing the formation of a withdrawal basin in the overlying sediments. Complete withdrawal of salt first occurs at the basin's center where the sediments are the thickest and then progresses outward. Once the salt is completely withdrawn from beneath the basin the thickest sediments form the core and the collapsed flanks of the withdrawal basin form the limbs of the turtle-shaped anticline.
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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.