UTIG RESEARCH PROJECTS ARCHIVEWas Laurentia the "southeast Pacific continent?"Principal Investigator: Ian W. D. Dalziel Funded by: National Science Foundation A new scenario for global Paleozoic paleogeography began to emerge three years ago with the publication of "SouthWest US - East Antarctica" ("SWEAT") hypothesis that East Antarctica-Australia had been juxtaposed with the Pacific margin of North America in the late Precambrian. It was also suggested at that time that the proto-Appalachian margin of Laurentia might have been juxtaposed with the Pacific margin of South America, the opening of the Pacific Ocean basin between Laurentia and East Antarctica in the late Precambrian to Cambrian being balanced on a globe of constant radius by the closure of pan-African and Brazilide ocean basins during assembly of Gondwana. Paleomagnetic data are in keeping with the idea that Laurentia made an "end-run" around the proto-Andean margin during the Paleozoic, perhaps colliding with it more than once. The hypothesis that the proto-Appalachian margin of Laurentia rifted from the
proto-Andean margin of South America at the end of the Precambrian, and that the
Appalachian and Andean orogens were initially a single mountain system resulting from
Paleozoic Laurentia-Gondwana interaction, has many and far-reaching implications. The work
proposed in Chile, Argentina, and possibly Peru is designed to test the "Laurentian
end-run" hypothesis, but will make significant contributions to understanding of the
origin and development of the Pacific margin of South America regardless of its validity. |