F.J. Shaub, 1983. "Origin of Catoche Tongue", 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:
The Catoche Tongue is a major reentrant in the Campeche Platform in the southeastern Gulf of Mexico (Figure 1, 1a). This feature extends about 125 km (77.6 mi) into the platform and varies in width from 25 to 100 km (15.5 to 62 mi). Bathymetric data indicate that the floor of the Tongue is a continuation of the Gulf of Mexico abyssal plain and that the steep margin of the Tongue is a continuation of the Campeche Escarpment which forms the outer margin of the Campeche Platform itself. The main questions about this feature are: (1) what is the mechanism of formation; (2) what is the age of formation; (3) do the margins of the Catoche Tongue consist of the same geologic section as the outer platform escarpment; and (4) what is the age and geology of the fill. Mechanism and margin similarities are interpreted in this paper by means of multichannel seismic data, and reason able suggestions are made as to age and lithology of fill by extrapolating published drilling results and regional geology.
The Campeche Platform itself, including the emergent Yucatan Peninsula, is a major geomorphological block with a steep escarpment boundary on its western, northern, and eastern sides. The Platform is probably underlain by Paleozoic metamorphic and igneous basement (Bryant et al, 1969; Baie, 1970; Viniegra, 1971, 1981; Schlager, Buffler et al, in press). The overlying sedimentary column recovered from Yucatan wells (i.e., the central platform area) consists of a thin section of Upper-Jurassic alternating marine and continental sediments and 2.5 to 3.5 km (1.5 to 2 mi) of Lower Cretaceous through Holocene shallow-marine carbonate facies and evaporites (Viniegra, 1971, 1981). At the outer platform margin shallow marine middle-Cretaceous deposition was confirmed by DSDP holes 86, 94, and 95 (Worzel, Bryant et al, 1973; Viniegra, 1971, 1981).
Lower Cretaceous reef and fore-reef material have also been dredged from the escarpment (Bryant et al, 1969) and drilled along its base (Schlager, Buffler, et al, in press). A shallow-marine environment, then, appears to have existed over the entire Campeche Platform during Early Cretaceous time. It was a "great thickness of limestone and evaporites" which formed as the upper surface of these deposits remained essentially at sea level while their base subsided (Garrison and Martin, 1973). However, in Late Cretaceous time the outer platform foundered, possibly because of an acceleration of the subsidence postulated above (Worzel, Bryant et al, 1973; Antoine et al, 1974). The outer platform strata thereafter consisted of foraminiferal ooze and chalk (Worzel, Bryant et al, 1973).
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.