TexasScholarWorks
    • Login
    • Submit
    View Item 
    •   Repository Home
    • UT Electronic Theses and Dissertations
    • UT Electronic Theses and Dissertations
    • View Item
    • Repository Home
    • UT Electronic Theses and Dissertations
    • UT Electronic Theses and Dissertations
    • View Item
    JavaScript is disabled for your browser. Some features of this site may not work without it.

    Seismic structural analysis of deformation in the southern Mexican Ridges

    Thumbnail
    View/Open
    txu-oclc-8661372.pdf (197.1Mb)
    Date
    1982-05
    Author
    Pew, Elliott
    Share
     Facebook
     Twitter
     LinkedIn
    Metadata
    Show full item record
    Abstract
    The southernmost region of the Mexican Ridges extends from Bryant's gap near 22.5 N latitude to the Campeche Knolls near 19.0 N latitude. Analysis of 23,030 kilometers of sparker and CDP seismic data from six surveys reveals the existence of two separate areas of folding, Zones 4a and 4b. In the Zone 4a foldbelt symmetrical folds form a gentle salient which parallels the curved outline of Isla de Tuxpan. Structural relief often in excess of 500 meters is reflected by similar bathymetric relief. Fold wavelengths average 10-12 kilometers. A detachment or decollement is interpreted in a thick Upper Cretaceous to Lower Tertiary pelagic shale sequence by the existence of relatively undeformed reflectors below this interval. The 3 to 3.5 kilometer thick allochthonous sheet has experienced approximately 1% shortening and a maximum displacement of 1 to 2 kilometers. The Zone 4a foldbelt appears to be a massive gravity slide. Folded Plio-Pleistocene strata establish the youth of these folds. A large deep-rooted structure of questionable origin is observed on GLG 22. This structure, exhibiting roughly 1500 meters of bathymetric relief, acts as a foreland buttress against which the gliding allochthonous mass deforms. The tightly appressed thrust-faulted folds up dip from the buttress exhibit anomalously short wavelengths. While no folding is observed directly down dip from the buttress, folding is observed 30 to 50 kilometers basinward of this structure just a few kilometers to the south. The boundary separating Zones 4a and 4b is a linear feature oriented transversely to regional strike and may be a tear fault. Reflections at depth are not continuous across this feature. The Zone 4b foldbelt lies directly down dip from the Veracruz Basin. Structural relief commonly doubling that observed in Zone 4a is rarely expressed as bathymetric relief. Individual folds are asymmetric, having gently dipping landward flanks and either steeply dipping or growth-faulted seaward flanks. Fold cores appear to contain diapiric material. Fold growth due to gravity sliding began in the Middle Miocene. Subsequent loading by a thick Middle-Upper Miocene section gradually halted downslope movement and initiated flowage of plastic substrata from beneath loaded synclinal troughs into anticlinal cores. This deformation has continued to the present in some folds.
    Department
    Geological Sciences
    Description
    text
    Subject
    Rock deformation--Mexico, Gulf of
    Geology, Structural--Mexico, Gulf of
    URI
    http://hdl.handle.net/2152/13919
    Collections
    • UT Electronic Theses and Dissertations

    University of Texas at Austin Libraries
    • facebook
    • twitter
    • instagram
    • youtube
    • CONTACT US
    • MAPS & DIRECTIONS
    • JOB OPPORTUNITIES
    • UT Austin Home
    • Emergency Information
    • Site Policies
    • Web Accessibility Policy
    • Web Privacy Policy
    • Adobe Reader
    Subscribe to our NewsletterGive to the Libraries

    © The University of Texas at Austin

     

     

    Browse

    Entire RepositoryCommunities & CollectionsDate IssuedAuthorsTitlesSubjectsDepartmentsThis CollectionDate IssuedAuthorsTitlesSubjectsDepartments

    My Account

    Login

    Statistics

    View Usage Statistics

    Information

    About Contact Policies Getting Started Glossary Help FAQs

    University of Texas at Austin Libraries
    • facebook
    • twitter
    • instagram
    • youtube
    • CONTACT US
    • MAPS & DIRECTIONS
    • JOB OPPORTUNITIES
    • UT Austin Home
    • Emergency Information
    • Site Policies
    • Web Accessibility Policy
    • Web Privacy Policy
    • Adobe Reader
    Subscribe to our NewsletterGive to the Libraries

    © The University of Texas at Austin