Structure of Precambrian crust in the U. S. from COCORP deep seismic profiling

Conference · Wed Jan 01 00:00:00 EST 1992 · Geological Society of America, Abstracts with Programs; (United States)

OSTI ID:5930447

Brown, L D ^[1]

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1. Cornell Univ., Ithaca, NY (United States)

COCORP and industry seismic reflection profiles probing beneath the thin veneer of Paleozoic sedimentary rocks of the US mid-continent are mapping a complex, largely unknown three dimensional mosaic of major fault zones and sutures, a highly variable Moho, and extensive sequences of unexplored volcanic and/or sedimentary strata. Key features of the Precambrian suggested by COCORP and other deep profiling include: Pervasive, distributed reflectivity, often diffractive, dominating the middle and lower crust. Moho that is rarely reflective, usually evident as a downward transition of distributed crustal reflectivity into mantle transparency. Volcano-clastic filled graben of the late Proterozoic Keweenawan rift buried beneath Paleozoic strata in Kansas and Michigan. Extensive, subhorizontal Precambrian stratification in the upper crust beneath the east- central US and the Texas-Oklahoma border region, argued to be either an extensive volcano-clastic basin, a voluminous felsic volcanic outpouring or a major intrusive sill complex. Crustal penetrating, dipping reflection zones that mark known (Grenville front) or inferred (Cashocton zone, Trans-Hudson orogen) shear zones. Non-reflective ( ) basement beneath the Appalachian foreland suggesting transparent massifs'' that serve as collisional buttresses during terrane accretion. Deep structure is sometimes at odds with simple extrapolations of surface geology. Clearly deep seismic profiling has only begun to reveal the buried craton in the US. It is time for an integrated program for the systematic exploration of this special scientific frontier.

• OSTI ID: 5930447
• Report Number(s): CONF-921058-; CODEN: GAAPBC
• Journal Information: Geological Society of America, Abstracts with Programs; (United States), Vol. 24:7; Conference: 1992 annual meeting of the Geological Society of America (GSA), Cincinnati, OH (United States), 26-29 Oct 1992; ISSN 0016-7592
• Country of Publication: United States
• Language: English

Related Subjects

58 GEOSCIENCES
CONTINENTAL CRUST
GEOLOGIC STRUCTURES
USA
DEPTH
GEOLOGIC FAULTS
PRECAMBRIAN ERA
REFLECTIVITY
SEISMIC SURVEYS
VOLCANIC REGIONS
DEVELOPED COUNTRIES
DIMENSIONS
EARTH CRUST
GEOLOGIC AGES
GEOLOGIC FRACTURES
GEOPHYSICAL SURVEYS
NORTH AMERICA
OPTICAL PROPERTIES
PHYSICAL PROPERTIES
SURFACE PROPERTIES
SURVEYS
580000* - Geosciences