Affiliation: | (1) Department of Geology, Imperial College of Science and Technology, SW7 2BP London, England;(2) Department of Geology, University of Georgia, 30602 Athens, Georgia, USA;(3) Present address: Nova Scotia Department of Mines and Energy, B3J 2X1 Halifax, N.S., Canada;(4) Department of Mathematics and Statistics, University of Delaware, 19711 Newark, Delaware, USA |