Classification Data
Found on the surface of the desert. Brecciated stones of total mass 21.270 kg; 37 pieces. Nature of recovery site: rocky planes with carbonate stones, low areas covered with quarz-carbonate sand overgrown by low small bushes. Classification: eucrite, cumulate. Black impact melt veins and pockets are abundant. Classified by Dr. Marina A. Ivanova, Vernadsky Institute of Geochemistry and Analytical Chemistry of the Russian Academy of Sciences (RAS), Kosygin St. 19, Moscow 117795, e-mail venus@glasnet.ru. Sample used for classification has been deposited to Committee on Meteorites of the Russian Academy of Sciences (RAS) Vernadsky Institute of Geochemistry and Analytical Chemistry of the Russian Academy of Sciences (RAS), Kosygin St. 19, Moscow 117795, e-mail venus@glasnet.ru. Key classification information: Fs of pyroxene vary from 38 to 46 (mol %), An of plagioclase is 92 (mol %). Analyzed by Dr. N. N. Kononkova, Vernadsky Institute of Geochemistry and Analytical Chemistry RAS.
A recent study by Yamaguchi et al. suggests that Dhofar 007 is an anomalous eucrite which may be related to mesosiderites. Below is the abstract from METEORITICS & PLANETARY SCIENCE, Volume 41, Issue 6 June 2006
An anomalous eucrite, Dhofar 007, and a possible genetic relationship with mesosiderites
Akira YAMAGUCHI1, 2*, Takehiko SETOYANAGI3, and Mitsuru EBIHARA1, 3
1Antarctic Meteorite Research Center, National Institute of Polar Research, Tokyo 173-8515, Japan
2Department of Polar Science, School of Multidisciplinary Science, Graduate University for Advanced Studies, Tokyo 173-8515, Japan
3Department of Chemistry, Tokyo Metropolitan University, Hachioji, Tokyo 192-0397, Japan
*Corresponding author. E-mail: yamaguch@nipr.ac.jp
We studied the texture, mineralogy, and bulk chemical composition of Dhofar 007, a basaltic achondrite. Dhofar 007 is a polymict breccia that is mostly composed of coarse-grained granular (CG) clasts with a minor amount of xenolithic components, such as a fragment of Mg-rich pyroxene. The coarse-grained, relict gabbroic texture, mineral chemistry, and bulk chemical data of the coarse-grained clast indicate that the CG clasts were originally a cumulate rock crystallized in a crust of the parent body. However, in contrast to monomict eucrites, the siderophile elements are highly enriched and could have been introduced by impact events. Dhofar 007 appears to have experienced a two-stage postcrystallization thermal history: rapid cooling at high temperatures and slow cooling at lower temperatures. The presence of pigeonite with closely spaced, fine augite lamellae suggests that this rock was cooled rapidly from higher temperatures (>0.5 °C/yr at ~1000 °C) than typical cumulate eucrites. However, the presence of the cloudy zone in taenite and the Ni profile across the kamacite-taenite boundaries indicates that the cooling rate was very slow at lower temperatures (~1–10 °C/Myr at <600–700 °C). The slow cooling rate is comparable to those in mesosiderites and pallasites. The two-stage thermal history and the relative abundance of siderophile elements similar to those for metallic portions in mesosiderites suggest that Dhofar 007 is a large inclusion of mesosiderite. However, we cannot rule out a possibility that Dhofar 007 is an anomalous eucrite.
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