Jurassic, Cretaceous, and Tertiary stratigraphy is analyzed

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in relation to its plate tectonic significance. Based on the I. O. Norton-J. G. Sclater reconstructions for the breakup of southern Gondwana, a scheme is developed illustrating the plate tectonic evolution from Triassic to present that includes (1) opening of the south Atlantic-Indian Ocean areas, (2) the formation of a marginal basin in the southern Andes in Late Jurassic-Early Cretaceous and its subsequent destruction by arc-continent collision and attendant ophiolite obduction, and (3) interaction during the Tertiary of the convergent Pacific margin and a northward migrating RRR triple junction.

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