Abstract: Continental Drift in Space and Time

By

Robert S. Dietz
ESSA, Atlantic Oceanographic & Meteorological Labs, 901 South Miami Avenue,
Miami, Florida, 33130

Computerized matching of 1,000-fm isobaths has resulted in a satisfying continental drift reconstruction of Pangaea, complemented by a closing of the Atlantic and Indian rift oceans as of -200 m.y. (mid-Triassic). A series of maps is offered which displays the drift dispersion of the continents at the end of the Triassic, Jurassic, Cretaceous, and Cenozoic. Paleomagnetics (both polar and reversal methods) are used as guides as well as some assumed rules of sea floor spreading and plate tectonics. Absolute geographic coordinates are inferred by using the Walvis "hot spot" as a non-drifting fix.

Sizeable overlaps and underlaps remain in the Pangaea reconstruction which must be obviated before it is acceptable. A case in point is the Bahama platform, which overlaps onto Africa when the North Atlantic is closed. This projection from the North American craton appears to have been laid down on oceanic crust in a small "window" opened with the initial breakup of Laurasia. Shallow-water carbonates were subsequently deposited on the subsiding clastic infill after it was stranded on the North American plate by further drifting.

Detailed understanding of the mechanics breakup and of the mismatches are of much interest for off-shore oil exploration.

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