CRYSTALLINE MICROMETEORITES FROM GREENLAND BLUE LAKES - THEIR CHEMICAL-COMPOSITION, MINERALOGY AND POSSIBLE ORIGIN

Among the different populations of cosmic particles found in the Greenland cryoconites, the irregular-shaped population is probably the most interesting one because it provides direct information about the nature of small meteoroids that impact the Earth. Petrographic and trace element analyses of this material reveal two main families labelled as coarse-grained (CG) and fine-grained (FG) which have, respectively, compact and porous structures. We have restricted our study to the coarse-grained particles which contain large relic minerals and thus are well adapted to the SEM and microprobe analysis techniques. We compare the mineralogical associations of 49 coarse-grained particles to that of meteorites and find that a majority of them belong to the same population of mineral grains previously found in CM chondrites and a minority of ordinary chondrites. © 1990.