Paleomagnetic Study of the Cretaceous Atajaña Formation and the Arica Dike Swarm, Northernmost Chile

Abstract

Remanent magnetization directions were obtained from 28 red sandstone samples of the Lower Cretaceous Atajaña Formation. Paleomagnetic studies were also performed on 103 igneous rock samples taken from 19 dikes in the Arica dike swarm, which intrudes into the Atajaña Formation sandstone. They showed 10°–15° counterclockwise rotation of the Arica region, northernmost Chile, with respect to the stable South American platform. These data suggest that the northernmost Chilean region underwent a tectonic rotation at least after the Cretaceous period, as the southern end of the Peruvian block. © 1985, Society of Geomagnetism and Earth, Planetary and Space Sciences. All rights reserved.