Locating the Shannawona Fault: Field and Geobarometric Studies from the Galway Batholith, Western Ireland

Abstract

Abstract:The Shannawona Fault Zone is a critical region of the Galway Batholith, juxtaposing deep-level Central Block lithologies against shallower-level granites of the Western Block. This paper presents results of the first detailed field mapping of the Shannawona Fault Zone between Casla Bay and Lackadunna Hill. Here the Shannawona Fault is not a discrete structure, but bifurcates and conjoins repeatedly to form an anastomosing fault system. Minor fault-bounded blocks defined by this fault system are lithologically associated with the Western Block New geobarometric studies undertaken in the area reveal a contrast of >1kbar in crystallisation pressures across the main Shannawona Fault, as identified from the field mapping Geobarometry indicates that the minor fault-bounded blocks originated at depths similar to the Western Block.