¹Xie, X., ^“Chen, M., ³Zhai, S., ¹Wang, F.
¹Key Laboratory of Mineralogy and Metallogeny, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China
²State Key Laboratory of Isotope Geochemistry, Guangzhou Institute of Geochemistry, Chinese Academy of Sciences, Guangzhou, China
³Key Laboratory of Orogenic Belts and Crustal Evolution, MOE, School of Earth and Space Sciences, Peking University, Beijing, China

An assemblage with FeNi metal, troilite, Fe-Mn-Na phosphate, and Al-free chromite was identified in the metal-troilite eutectic nodules in the shock-produced chondritic melt of the Yanzhuang H6 meteorite. Electron microprobe and Raman spectroscopic analyses show that a few phosphate globules have the composition of Na-bearing graftonite (Fe,Mn,Na)3(PO4)2, whereas most others correspond to Mn-bearing galileiite Na(Fe,Mn)4(PO4)3 and a possible new phosphate phase of Na2(Fe,Mn)17(PO4)12 composition. The Yanzhuang meteorite was shocked to a peak pressure of 50 GPa and a peak temperature of approximately 2000 °C. All minerals were melted after pressure release to form a chondritic melt due to very high postshock heat that brought the chondrite material above its liquidus. The volatile elements P and Na released from whitlockite and plagioclase along with elements Cr and Mn released from chromite are concentrated into the shock-produced Fe-Ni-S-O melt at high temperatures. During cooling, microcrystalline olivine and pyroxene first crystallized from the chondritic melt, metal-troilite eutectic intergrowths, and silicate melt glass finally solidified at about 950–1000 °C. On the other hand, P, Mn, and Na in the Fe-Ni-S-O melt combined with Fe and crystallized as Fe-Mn-Na phosphates within troilite, while Cr combined with Fe and crystallized as Al-free chromite also within troilite.

Reference
Xie X, Chen M, Zhai S, Wang, F (2014) Eutectic metal + troilite + Fe-Mn-Na phosphate + Al-free chromite assemblage in shock-produced chondritic melt of the Yanzhuang chondrite. Meteoritics & Planetary Science (in Press)
Link to Article [doi: 10.1111/maps.12379]

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