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Break-up of Gondwana and opening of the South Atlantic: Review of existing plate tectonic models

January 1, 2007

The opening history of both the Weddell Sea and South Atlantic Ocean is critical to understanding the break-
up of Gondwana and the evolution of Antarctica since Early Jurassic times. The dispersal of the Gondwanide fragments
is important to understanding the development of past ocean circulation. Unfortunately the tectonics of the Weddell Sea
region is difficult to resolve because of the paucity of data coverage and the region’s inherent complexity. Although
considerable progress has been achieved in the past 20 years with new marine aeromagnetic data and satellite derived
gravity anomaly maps, there are still several models in consideration which differ in crustal ages and schemes of opening. In this paper we present a review of four of those models. Focusing on poles of rotation, synthetic isochrons and
flowlines, we proceed backward in time beginning at Chron 34 (83.5 Ma), as it is relatively well defined ocean wide,
and present crustal age maps that display the estimated trace of the South America-Antarctica-Africa triple junction for
each model. We also plot reconstructions at four selected epochs for all models using the same projection and scale to facilitate comparison. The diverse simplifying assumptions that need to be made in every case regarding plate fragmentation to account for the numerous syn-rift basins and periods of stretching are strong indicators that rigid plate tectonics is too simple a model for the present problem.

Publication Year 2007
Title Break-up of Gondwana and opening of the South Atlantic: Review of existing plate tectonic models
DOI 10.3133/ofr20071047SRP055
Authors M.E. Ghidella, L.A. Lawver, L.M. Gahagan
Publication Type Report
Publication Subtype USGS Numbered Series
Series Title Open-File Report
Series Number 2007-1047-SRP-055
Index ID ofr20071047SRP055
Record Source USGS Publications Warehouse