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    Structure of the southern Keweenawan rift from COCORP surveys across the Midcontinent Geophysical Anomaly in northeastern Kansas

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    SteeplesD_Tectonics_3(3)367.pdf (1.710Mb)
    Issue Date
    1984-06
    Author
    Serpa, L.
    Setzer, T.
    Farmer, H.
    Brown, L.
    Oliver, James
    Kaufman, S.
    Sharp, J.
    Steeples, Don W.
    Publisher
    American Geophysical Union
    Type
    Article
    Article Version
    Scholarly/refereed, publisher version
    Metadata
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    Abstract
    COCORP profiling across the midcontinent geophysical anomaly in northeastern Kansas reveals structural basins and other features of the Precambrian Keweenawan rift buried beneath the Phanerozoic cover. The 40-km-wide main basin is asymmetric, with a maximum depth of 3 km on the east and 8 km on the west. The basin fill is characterized by a lower layered sequence of strong continuous west dipping reflectors which may be correlated with Middle Keweenawan interbedded volcanic and clastic rocks exposed along the MGA in the Lake Superior region. Overlying this layered sequence is a zone of weak, discontinuous reflectors correlated here with the predominantly clastic rocks characteristic of the Upper Keweenawan sequence near Lake Superior. A second tilted but shallower basin lies to the east of the main basin and appears to be filled predominantly with clastic sedimentary rocks. The character of the seismic data, the seismic velocity distribution, and gravity modeling suggest that mafic intrusions lie beneath the main rift basin. Normal faults associated with the rift dip at moderate angles to the east. Palinspastic reconstruction indicates that the rift basin formed by the rotation of fault bounded blocks during crustal extension. Although reactivation of preexisting structures appears to have occurred in many other rifts profiled by COCORP, the evidence is inconclusive on this point in the case of the Kansas data. The structures mapped by COCORP surveys in Kansas and elsewhere suggest that asymmetric sequences of layered reflectors are characteristic, and perhaps diagnostic, of rift basin deposits in general.
    Description
    This is the published version. Copyright 1984 American Geophysical Union. All Rights Reserved.
    URI
    http://hdl.handle.net/1808/17107
    DOI
    https://doi.org/10.1029/TC003i003p00367
    Collections
    • Geology Scholarly Works [247]
    Citation
    Serpa, L., T. Setzer, H. Farmer, L. Brown, J. Oliver, S. Kaufman, J. Sharp, and D. W. Steeples (1984), Structure of the Southern Keweenawan Rift from COCORP Surveys across the midcontinent geophysical anomaly in northeastern Kansas, Tectonics, 3(3), 367–384, http://dx.doi.org/10.1029/TC003i003p00367.

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    Contact KU ScholarWorks
    785-864-8983
    KU Libraries
    1425 Jayhawk Blvd
    Lawrence, KS 66045
    785-864-8983

    KU Libraries
    1425 Jayhawk Blvd
    Lawrence, KS 66045
    Image Credits
     

     

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