1. Reactivation Research Group, Department of Earth Sciences, Durham University, Durham DH1 3LE, UK
2. Current address: BP Exploration and Production, Chertsey Road, Sunbury on Thames, Middlesex TW16 7LN, UK
3. Department of Geology, University of Leicester, University Road, Leicester LE1 7RH, UK
4. School of Earth & Environmental Sciences, University of Portsmouth, Burnaby Road, Portsmouth PO1 3QL, UK