Hudson Bay Basin
V. Dimian, R. Gray, J. Stout, B. Wood, 1983. "Hudson Bay 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 Hudson Bay basin is a cratonic basin situated in the central part of the Canadian Shield. Its basement is composed of crystalline rocks belonging to the Superior Province (2.9 Ga) in the southern and central part and to the Churchill Province (1.6 to 1.9 Ga) in the northern part. The eastern part of the basement of the basin has been affected by the Hudsonian Crogeny.
The Hudson Bay basin is filled with Paleozoic sediments with a thickness of at least 1,576 m (5,170 ft) proven by drilling in the central part of the basin. The subsidence and sedimentation rates were moderate with several periods of uplift and erosion during the Paleozoic. The Mesozoic is absent in the Hudson Bay basin.
The Paleozoic sedimentation, typical of a cratonic basin (Figure 1), started in Upper Ordovician time with basal orthoquartzitic sandstones, and continued with platform-type limestones and dolomites with some anhydride and salt (Bad Cache Rapids and Churchill River Groups). Oil shales 2 to 8 cm (1 to 3 in) thick are interbedded in the upper part of Bad Cache Rapids group carbonates outcropping on Southampton Island. A few similar but thinner interbeds, in a similar position, occur in carbonates in the Kaskattama well also onshore in the Hudson Bay Lowlands.
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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.