T.D. Crutcher, 1983. "Baltimore Canyon Trough", 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 Baltimore Canyon Trough is an elongate sedimentary basin bounded on the north by the Long Island Platform and on the south, less precisely, by a basement promontory offshore from Cape Hatteras. The Trough probably has been open to the sea to the east through most of its history.
The seismic line is approximately 75 mi (120 km) long and extends from a point 20 mi (32 km) from the New Jersey coastline eastward to the 3,000 ft (914 m) isobath. The reflector at 1.84 secs, at the west end of the line, probably represents the 'breakup unconformity' of Falvey (1974) which is inferred to be Early Jurassic in age here. Beneath the unconformity the section may be comprised of Paleozoic metamorphic or igneous rocks and/or Triassic to Lower Jurassic synrift continental clastics. Above the unconformity are Lower Jurassic evaporites overlain by a wedge of Middle Jurassic through Lower Cretaceous Neocomian shelf carbonates and clastics. The shelf sequence is 25,000 to 30,000 ft (7,620 to 9,144 m) thick in the center of the trough. It was built during a progradational mega-cycle that advanced the shelf edge 25 mi (40 km) seaward from its initial position following plate separation. Most of the post-Neocomian section is composed of shallow marine clastics deposited during the long Cretaceous period of relative sea-level rise.
Near the center of the seismic line is the "Great Stone Dome." This ultramafic body (lamprophere has been identified in well cuttings) intruded the Baltimore Trough during middle Early Cretaceous time. Some intrusive bodies of inferred igneous origin seaward of Georges Bank Basin, 270 mi (435 km) to the east-northeast, were also emplaced during Early Cretaceous time. These bodies are on trend with the Kelvin Seamounts and the Kelvin Fault Zone.
After a period of erosion which nearly base-leveled the Dome, a blanket of lower Lower Cretaceous clastic rocks was deposited across the uplift area before rejuvenation of the Dome occurred during Late Cretaceous and early Tertiary time. The nearly circular dome has an areal closure of nearly 47,000 acres at the Upper Cretaceous level. Seven exploratory wells have been drilling on the anomaly by industry. None is believed to have encountered significant hydrocarbon shows.
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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.