IGDI


Eucrite
Monomict breccia, noncumulate
(Main Group–Nuevo Laredo trend)

standby for igdi photo
Found February 2000
29° 14' N., 8° 22' W.

A 1,470 g meteorite was recovered in several pieces in Morocco. Igdi is composed of plagioclase, pigeonite with exsolved clinopyroxene, silica, ilmenite, chromite, and troilite. The Nuevo Laredo trend eucrites are thought to be the product of in situ crystallization of residual melts in a differentiating magma ocean. This origin is consistent with the decoupling between major elements and incompatible trace elements; i.e., for an increase in incompatible element abundances there is a decrease in Mg/(Mg + Fe). On a plot of Mg# versus an incompatible element such as Ti, Igdi falls comfortably within the Nuevo Laredo trend meteorites. The Nuevo Laredo trend has been combined with the Main Group eucrites in the currently recognized classification scheme (Barrat et al., 2007).

In a study of several Antarctic non-cumulate basaltic eucrites by Bermingham et al. (2008), a possible new subgroup was identified. In contrast to the other eucrites studied, members of this new subgroup exhibit LREE-depleted patterns with positive Eu anomalies, and other incompatible trace element abundances are lower than those in the other non-cumulate basaltic eucrites studied. Moreover, in contrast to the plagiophile elements in the other eucrites studied, the new subgroup contains higher Sr/Nd ratios when plotted against the magnitude of the Eu anomaly. It was proposed that this new subgroup might represent a parental source which was enriched in a plagioclase melt. It should be considered that high Sr, Ba, and Pb concentrations could be the result of severe weathering. The specimen of Igdi shown above is a 2.2 g complete slice.