Detailed Cretaceous reconstruction model for the South Atlantic

The temporal resolution of plate reconstruction models linearily depends on the frequency at which the geomagnetic field flipped its polarity. Accordingly, past plate motions during the long period of the Cretaceous normal superchron (CNS, 83.5-120.6 Ma) is poorly resolved. Recent findings on the behaviour of the geomagnetic field during the CNS (Granot et al., 2012) provide two new time markers that may be used to define internal isochrons within the Quiet zones. Here we present preliminary results of the first attempt to utilize these magnetic anomalies (Q2 and Q1, 108 and 92 Myr ago, respectively) in the South Atlantic Cretaceous Quiet zones. We have 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 detail the break-up of Africa and South America. We confirm the validity of the results by tracing the fracture zones with synthetic flowlines and predictions of magnetic anomalies location outside of our studied area. Based on these new rotation parameters, we present kinematic analysis that shed new light on the major changes in plate motion that took place in the South Atlantic during the Cretaceous. Granot, R., J. Dyment, and Y. Gallet, Geomagnetic field variability during the Cretaceous Normal superchron, Nature Geoscience, V. 5, 220-223, 2012