DaG 872 has recently been classified as a eucrite [Patzer, A. et al (2002) LPSC XXXIII, Abstract # 1106], but subsequent oxygen isotope data suggests a possible lunar origin. Additional studies will be conducted to resolve this apparent contradiction.
METEORITICS & PLANETARY SCIENCE, Volume 38, Issue 5, May 2003, Abstract
New eucrite Dar al Gani 872: Petrography, chemical composition, and evolution.
Andrea PATZER,* Dolores H. HILL, and William V. BOYNTON
*Corresponding author. Lunar and Planetary Laboratory, University of Arizona, Tucson, Arizona 85721, USA.
Dar al Gani 872 (DaG 872) is a new meteorite from Libya that we classified by means of Instrumental Neutron Activation Analysis (INAA), electron microprobe, and optical microscopy. According to our results, DaG 872 is a Mg-rich main group eucrite, i.e., a monomict noncumulate basaltic eucrite displaying a predominant coarse-grained relict subophitic and a fine-grained granulitic texture. The meteorite also shows pockets of late-stage mesostasis and is penetrated by several calcite veins due to terrestrial weathering. Finally, it exhibits shock phenomena of stage 1–2 including heavily fractured mineral components, undulose extinction of plagioclase, kinked lamellae, and mosaicism in pyroxenes corresponding to peak pressures of ~20 GPa. In view of petrographic criteria as well as compositional and exsolution characteristics of its pyroxenes, the sample represents a metamorphic type 5 eucrite. Assuming the metamorphic type to be a function of burial depth on the parent body and taking into account the relatively high shock stage, the excavation of DaG 872 was likely induced by a major impact event. Prior to this point, DaG 872 apparently underwent a 4-stage geological evolution that is reflected by intricate textural and mineralogical features.
Lunar and Planetary Science XXXIII (2002): Abstract # 1106
Dar al Gani 872: Yet another eucrite, yet another lesson to learn?