New eucrite Dar al Gani 872: Petrography, chemical composition, and evolution

Abstract

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.

The new polymict eucrite Dar al Gani 983: Petrography, chemical composition, noble gas record, and evolution

“…3). This textural detail implies turbulent crystallization conditions similar to those inferred for the noncumulate eucrite DaG 872 (Patzer et al 2003b).…”

HED-like cosmic spherules from the Transantarctic Mountains, Antarctica: Major and trace element abundances and oxygen isotopic compositions

“…Field for chondrites and trends for achondrites are from Goodrich and Delaney (2000). The bulk compositions of eucrites, howardites and diogenites (HEDs) from literature are shown for comparison (McCarthy et al, 1973;Fukuoka et al, 1977;Floran et al, 1981;Cleverly et al, 1986;Laul and Gosselin, 1990;Lindstrom, 1993, 2003;Mittlefehldt, 1994;Kitts and Lodders, 1998;Barrat et al, 1999Barrat et al, , 2000Barrat et al, , 2003Barrat et al, , 2007Barrat et al, , 2009Buchanan et al, 2000;Papike et al, 2000;Patzer et al, 2003Patzer et al, , 2005Yamaguchi et al, 2009). is a reliable technique for a first identification of differentiated particles in large micrometeorite collections.…”

Characterization of achondritic cosmic spherules from the Widerøefjellet micrometeorite collection (Sør Rondane Mountains, East Antarctica)

“…8). For S-type cosmic spherules, Fe isotope fractionation appears to be negatively correlated with the FeO (1986), Lindstrom (1993, 2003), Kitts and Lodders (1998), Barrat et al (2000Barrat et al ( , 2007, Buchanan et al (2000), Patzer et al (2003Patzer et al ( , 2005 and Yamaguchi et al (2009). Reference values for 'mare basalts' from Haskin and Warren (1991).…”

“…Trace element compositions of the achondritic spherules. Reference values for 'eucrites' from McCarthy et al (1973), Cleverly et al(1986), Lindstrom (1993, 2003),Kitts and Lodders (1998),Barrat et al (2000Barrat et al ( , 2007,Buchanan et al (2000),Patzer et al (2003Patzer et al ( , 2005 andYamaguchi et al (2009). Reference values for 'mare basalts' fromHaskin and Warren (1991).…”