Home ]

 

SWLGS Luncheon Topics

Updated Jan. 10, 2009

Jan. 13, 2009

 Jurassic Kinematics of the Gulf of Mexico and Surrounding Regions

  Dale Bird, Bird Geophysical

 


Abstract Summary

The formation of the Gulf of Mexico is best considered within a larger framework that also includes the opening of the Central Atlantic Ocean and the assembly of Mexico. Closing ocean basins along geomagnetic isochrons is an objective way of reconstructing continents because, in general, intracontinental extension stops on passive margins once new oceanic lithosphere is created. The size and shape of the Gulf of Mexico prevent mapping seafloor spreading anomalies, however its evolution can be considered in the context of closed Atlantic Ocean basins and the eastern crustal blocks of Mexico. Holding Africa fixed, we closed the South Atlantic Ocean to Chron M4 (126.6 Ma) and the Central Atlantic Ocean to Chron M40 (165.1 Ma). In this configuration, and with the Gulf of Mexico closed by clockwise rotation of the Yucatan continental block (~42 degrees), the positions of North America and South America indicate that the Gulf of Mexico opened at least 20 My after the opening of the Central Atlantic Ocean (ca. 180 Ma). The Gondwanan parts of eastern Mexico, Yucatan, Florida, and the United States south of the Suwaneee-Marathon Suture, remained attached to Laurasia after the breakup of Pangea. The Gulf of Mexico formed, in Late Jurassic to earliest Cretaceous times (ca. 160 Ma to 140 Ma), by continental extension and sea floor spreading as the Yucatan block rotated counterclockwise (~42 degrees).

Two prominent basement structures, defined by seismic refraction and gravity data, are interpreted to be hotspot tracks created by a single mantle plume during this rotation. A third prominent basement structure is interpreted to be a marginal ridge that formed along the ocean-continent boundary as the transform fault between the Yucatan block and eastern Mexico developed. Sea-floor spreading in the Gulf of Mexico is associated with a ridge-centered mantle plume eruption (ca. 150 Ma to 140 Ma) that produced two hotspot tracks initially on North American Plate and the Yucatan block, and then a single hotspot track on the Yucatan block. An ocean-continent boundary can be interpreted by connecting the endpoints of the hotspot tracks with the outboard edge of the marginal ridge. Salt deposition on extended continental crust was widespread at a time between ca. 160 Ma and ca.150 Ma.

  • Bird, D. E., 2001, Shear margins: continent  ocean transform and fracture zone boundaries: The Leading Edge, vol. 20, no. 2, pp. 150-159.
  • Bird, D. E., Burke, K., 2006, Pangea breakup: Mexico, Gulf of Mexico, and Central Atlantic Ocean: in, Expanded Abstracts of the Technical Program: Society of Exploration Geophysicists 76th Annual International Meeting and Exposition, pp. 1013-1016.
  • Bird, D. E., Burke, K., Hall., S. A., Casey, J. f., 2005, Gulf of Mexico tectonic history: Hotspot tracks, crustal boundaries, and early salt distribution: Am. Assoc. Petr. Geol. Bull., 89, 311-328.
  • Bird, D. E., Hall, S. A., Burke, K., Casey, J. F., Sawyer, D. S., 2008, Mesozoic seafloor spreading history of the Central Atlantic Ocean: Conjugate Margins Conference, Dalhousie Univ., Halifax, Nova Scotia
  • Bird, D. E., Hall, S. A., Burke, K., Casey, J. F., Sawyer, D. S., 2007, Early Central Atlantic Ocean seafloor spreading history: GeoSphere, vol. 3, 282-298.


 

Biographical Sketch

 

 After serving honorably in the U.S. Army (1st Military Intelligence Battalion) Dale has worked with Aero Service, Digicon, Marathon, World Geoscience, and Aerodat. In 1997 he established Bird Geophysical. Dale has earned three degrees in geophysics from the University of Houston: BS, MS and Ph.D. (2004).  He is a licensed Texas Professional Geoscientist and a member of several professional organizations.


 

 

D