1 Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, 2020-2207 Main Mall, Vancouver, V6T 1Z4, Canada. msmit@eoas.ubc.ca.
2 Department of Geosciences, Swedish Museum of Natural History, Frescativägen 40, SE-104 05, Stockholm, Sweden. msmit@eoas.ubc.ca.
3 Department of Earth, Ocean and Atmospheric Sciences, University of British Columbia, 2020-2207 Main Mall, Vancouver, V6T 1Z4, Canada.