Plate kinematics beyond geomagnetic reversals: the South Atlantic Ocean during the Cretaceous superchron

R Granot, J Dyment

Research output: Chapter in Book/Report/Conference proceedingConference contribution

Abstract

Globally correlatable marine magnetic anomalies record past polarity reversals and changes in the strength of the dipolar geomagnetic field. Traditionally, plate reconstruction models rely on reversals-related anomalies leading to a well-known major temporal gap and tectonic ambiguities in the existing kinematic models for the Cretaceous normal superchron (120.6-83.5 Ma), a long period when no polarity reversal took place. Recent findings on the behavior of the geomagnetic field during the superchron (Granot et al., 2012) provide new time markers that may be used to define internal isochrons within the Quiet Zones. We examined the magnetic anomalies above the slow to intermediate spreading South Atlantic Quiet Zones to build a new kinematic model for the opening of the basin. We calculated six sets of finite rotation parameters for Anomalies M4 (126.5 Ma), M0 (120.6 Ma), Q2 (~108 Ma), Q1 (~92 Ma), C34 (83.5 Ma) and C33r (79 Ma) that illuminate in details the break-up and initial drift of Africa and South America. We confirm the validity of these results by tracing the fracture zones with synthetic flowlines and by predicting the location of magnetic anomalies outside of our studied area. Based on these new rotations we present the first magnetically-constrained opening model for the Equatorial Atlantic Gateway.
Original languageEnglish
Title of host publicationAmerican Geophysical Union, Fall Meeting 2013
PagesGP11A-02
StatePublished - 2013

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