CompuServe Messages

Hello, Doug: <<last I heard on the subject, people were still wrangling about how carbonatites formed.>> No one seriously questions that it is possible to form a carbonate melt anymore – it's verified by experiment and observation (e.g. East African carbonate lavas). I believe that the mechanisms of emplacement for kimberlites & carbonatites (commonly occuring as diatremes, or "pipes") may not be terribly well understood as yet. <<Perhaps the wrangling has more to do with where the calcite lava originates – is it melted limestone or does it come from beneath the crust?>> The source regions are (almost certainly) subcrustal. If you can be patient for a couple of days, I'll thumb through some back issues of _Science_ and my technical references to dig out more info than I can pull off the top of my head <g>. Talk to you later! Scott M.