1. Department of Earth Sciences, University of Oregon, Eugene, Oregon 97403, U.S.A.
2. Department of Earth and Environmental Science, University of Michigan, Ann Arbor, Michigan 48109, U.S.A.,
3. Department of Marine Biology, Department of Wildlife and Fisheries Sciences, Texas A&M University, Galveston, Texas 77553, U.S.A.
4. Department of Earth Sciences, Clark Honors College, University of Oregon, Eugene, Oregon 97403, U.S.A.,