New Data on the Ben Levy Anticline, With Reverse Reactivation on the Coolin Fault Giving Up-Side-Down Silurian Rocks in Joyces Country, Connemara

Abstract

In Joyces Country in western Ireland, the ~ E-W striking axial plane of the D7 Ben Levy anticline folded Dalradian and unconformable Silurian rocks. The north side of the fold is mostly coincident with the contemporaneous ESE-WNW striking steeply dipping Coolin Fault close to the Dalradian-basal Silurian contact. This fault was first initiated by sinistral strike-slip motion, probably of Ordovician age, and then secondly used by post-Wenlock down throw on the north side to form the D7 anticline. Later a newly recognised third motion of reverse reactivation on the fault uplifted the north limb of the fold and locally overturned the Silurian succession against irregularities in the SSW dip of the fault. Still later, but pre-374Ma (Devonian), NE-SW faulting exposed different previous levels of the Coolin Fault zone. The superb Dalradian rock exposure provides details not generally apparent on other reactivated faults in Connemara.