Eintrag weiter verarbeiten
Genesis of the IIICD iron meteorites: Evidence from silicate‐bearing inclusions
Gespeichert in:
| Zeitschriftentitel: | Meteoritics |
|---|---|
| Personen und Körperschaften: | , , , |
| In: | Meteoritics, 28, 1993, 4, S. 552-560 |
| Format: | E-Article |
| Sprache: | Englisch |
| veröffentlicht: |
Wiley
|
| Schlagwörter: |
| Zusammenfassung: | <jats:p><jats:bold>Abstract—</jats:bold> Our studies of the silicate‐bearing inclusions in the IIICD iron meteorites Maltahöhe, Carlton and Dayton suggest that their mineralogy and mineral compositions are related to the composition of the metal in the host meteorites. An inclusion in the low‐Ni Maltahöhe is similar in mineralogy to those in IAB irons, which contain olivine, pyroxene, plagioclase, graphite and troilite. With increasing Ni concentration of the metal, silicate inclusions become poorer in graphite, richer in phosphates, and the phosphate and silicate assemblages become more complex. Dayton contains pyroxene, plagioclase, SiO<jats:sub>2</jats:sub>, brianite, panethite and whitlockite, without graphite. In addition, mafic silicates become more FeO‐rich with increasing Ni concentration of the hosts. In contrast, silicates in IAB irons show no such correlation with host Ni concentration, nor do they have the complex mineral assemblages of Dayton. These trends in inclusion composition and mineralogy in IIICD iron meteorites have been established by reactions between the S‐rich metallic magma and the silicates, but the physical setting is uncertain. Of the two processes invoked by other authors to account for groups IAB and IIICD, fractional crystallization of S‐rich cores and impact generation of melt pools, we prefer core crystallization. However, the absence of relationships between silicate inclusion mineralogy and metal compositions among IAB irons analogous to those that we have discovered in IIICD irons suggests that the IAB and IIICD cores/metallic magmas evolved in rather different ways. We suggest that the solidification of the IIICD core may have been very complex, involving fractional crystallization, nucleation effects and, possibly, liquid immiscibility.</jats:p> |
|---|---|
| Umfang: | 552-560 |
| ISSN: |
0026-1114
|
| DOI: | 10.1111/j.1945-5100.1993.tb00278.x |