Meteorite/Planetary Science Quiz

Question #9

What is the petrogenesis of ureilites?

Ureilites are assemblages of coarse-grained olivine and pyroxene with carbonaceous interstitial materials. Their petrogenesis (conditions of origin) has been debated for more than two decades.

Initially, the arguments centered mainly on whether ureilites are partial melt residues of primitive materials (created by nebula instead of planetary igneous processes) or magmatic cumulates (igneous). However with continuing studies, geochemical data has revealed them to have the characteristics of both.

Many petrogenetic models, either igneous or primitive have been proposed, but none of them have been successful in explaining all of the contrasting characteristics of these meteorites. During thirty years of research they have remained, as Dodd stated in "Meteorites: A Petrologic-Chemical Synthesis" (1981), "…. the most enigmatic of meteorites".

Back to Question 9