Decipher the driving force in continental drift from new insights about the South Atlantic breakup process

doi:10.13745/j.esf.sf.2021.12.27-en

Abstract

Abstract:

It has been widely recognized that the separation of the African and South American continents is caused by the South Atlantic breakup. The South Atlantic region is highly relevant to the development of the continental drift hypothesis. The driving force behind continental drift, however, has been in debate ever since the hypothesis was proposed. Therefore, quantitative analysis of the forces driving plate movement in the process of Atlantic breakup is particularly important. Here, we analyzed two deep seismic reflection survey profiles located on either side of the South Atlantic, in passive continental margin basins, and estimated the Moho dip angle of the African continent on the basis of tectonic geological interpretation. We then calculated the magnitude of crustal gravitational slip shear force along the Moho to explain the dynamic mechanism of African continent movement in the process of Atlantic breakup. We demonstrated that the African continental crust can produce a strong gravitational slip force on the inclined interface formed by mantle upwelling, and the shear force is greater in the south than in the middle part of the crust. According to our analysis, the continental crust can drift continuously by continuous hot mantle upwelling and gravitational slide. This model can reasonably explain the genetic mechanism for the many linear continental fragments in the Atlantic Ocean, and it can also provide an internal reason for why the South Atlantic today is wider in the south than it is in the middle. Based on this model we reconstructed the tectonic evolutionary history of the South Atlantic breakup process. This research established a new dynamic model of plate motion and provided more accurate constraint for understanding the driving force behind plate movement.

Key words: Atlantic breakup, African continental crust, South American continental crust, gravitational slip, continental drift

LIANG Guanghe, YANG Weiran. Decipher the driving force in continental drift from new insights about the South Atlantic breakup process[J]. Earth Science Frontiers, 2022, 29(1): 328-341.

Figures/Tables 8

References 44

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