Novel plate kinematic constraints show Africa-Eurasia convergence acceleration due to Neotethyan double subduction during the Cretaceous Normal Superchron

D. Gürer, R. Granot, D.~J.~J. Van Hinsbergen

Research output: Contribution to journalMeeting Abstract

Abstract

The motion history of tectonic plates shows remarkable variation through time. A recent hypothesis links rapid plate acceleration with the initiation of a double in line subduction zones (Jagoutz et al., 2015). An ideal test case for this hypothesis is the initiation of a several thousand-kilometer-long intra-oceanic subduction zone in the Neotethys between Africa-Arabia and Eurasia. Along with an already existing subduction zone along the southern Eurasian margin, this initiated a period of double subduction. Relics of the intra-oceanic subduction zone in the form of ophiolites found between Turkey and Oman show that forced subduction initiation occurred around ~105 Ma, and led to upper plate extension, likely marking the inception of slab pull and roll-back at ~96-90 Ma. Later arrival of continental crust to this subduction zone led to its demise between 85 and 70 Ma.

Using this example to test geodynamic effects of double subduction is problematic, however, because intra-oceanic subduction initiation occurred during the Cretaceous Normal Superchron (CNS, ~124-83 Ma), during which the relative plate motion is poorly constrained due to the lack of magnetic anomalies related to geomagnetic reversals. Here we use variations in the strength of the geomagnetic field (termed Q1 (92 Ma) and Q2 (108 Ma)), previously defined as within-superchron time markers (Granot et al., 2012), to compute two new intra-Cretaceous Normal Superchron North America - Africa rotation poles. This new kinematic model provides a major increase in the resolution of Cretaceous plate motions. An increase of up to 6 cm/yr Arabia-Eurasia plate convergence is evident during the CNS, mostly in the ~92-83 Ma interval. High convergence rates continued during the first chron after the CNS (i.e., C33r), followed by a rapid decrease of similar magnitude after 80 Ma. We positively test the hypothesis that double subduction may have a first-order effect on plate motions.
Original languageEnglish
JournalGeophysical Research Abstracts
Volume2019
StatePublished - 2019

Keywords

  • 7218 Lithosphere
  • SEISMOLOGY
  • 7220 Oceanic crust
  • 8120 Dynamics of lithosphere and mantle: general
  • TECTONOPHYSICS
  • 8416 Mid-oceanic ridge processes
  • VOLCANOLOGY

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