Phosphates in the Impact Associations of the Chelyabinsk Meteorite

IF 0.8 4区地球科学 Q4 GEOCHEMISTRY & GEOPHYSICS

Geochemistry International Pub Date : 2025-09-23 DOI:10.1134/S0016702925600476

V. V. Sharygin

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Abstract

Na–Fe and Na–Ca–Mg–Fe phosphates were found in the impact melt associations of the Chelyabinsk meteorite (Chebarkul fragment). They drastically differ in composition from phosphates of the initial chondrite (chlorapatite and merrillite). Chladniite Na_2.25Ca_2.14Mg_6.47Fe_3.76Mn_0.17(PO₄)₉ and a merrillite-like phase Na_1.32Ca_6.80Mg_2.07Fe_0.98Mn_0.04(PO₄)₇ were found in the silicate part in quenched interstitial groundmass between olivine grains; merrillite and chlorapatite are rare in it. The spongy metal–sulfide aggregate in the large vugs and metal–sulfide blebs in the silicate part contain Na–Fe phosphate globules. They consist of sarcopside and graftonite (Fe²⁺,Mn²⁺)₃(PO₄)₂, galileiite Na(Fe²⁺,Mn²⁺)₄(PO₄)₃, xenophyllite Na₄(Fe²⁺,Mn²⁺)₇(PO₄)₆, an unidentified Na–Fe phosphate Na₂(Fe²⁺,Mn²⁺)₁₇(PO₄)₁₂, and sometimes chromite-2. Dendritic–skeletal growth of crystals (providing evidence of very rapid quenching) is found in all associations of the impact melt (silicate part, vugs, metal–sulfide aggregate, metal–sulfide blebs, and phosphate globules). The following crystallization sequence is revealed in the Na–Fe phosphate globules: chromite-2 → sarcоpside/graftonite → galileiite → xenophyllite. They are thought to have formed due to the separation of Na–Fe phosphate liquid from homogenous Fe–Ni metal–sulfide melt enriched in Na, P, Cr, and O. The Na–Ca–Mg–Fe phosphates crystallized without involvement of any processes of liquid immiscibility, directly from silicate melt. The paper provides data on the chemical composition and Raman spectroscopy of all studied phosphates and the major minerals of the impact melt associations of the Chelyabinsk meteorite.

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车里雅宾斯克陨石撞击协会中的磷酸盐

在车里雅宾斯克陨石（Chebarkul碎片）的撞击熔体结合体中发现了Na-Fe和Na-Ca-Mg-Fe磷酸盐。它们在组成上与最初球粒陨石（绿磷灰石和merrillite）的磷酸盐有很大的不同。在橄榄石晶粒间质淬火的硅酸盐部分，发现了一种似软晶石的相：Na2.25Ca2.14Mg6.47Fe3.76Mn0.17(PO4)9和Na1.32Ca6.80Mg2.07Fe0.98Mn0.04(PO4)7；镁磷灰石和绿磷灰石是罕见的。大孔洞中的海绵状金属硫化物聚集体和硅酸盐部分的金属硫化物泡含有磷酸钠铁球。它们由石蜡和接枝石（Fe2+,Mn2+）3(PO4)2，铁橄榄石Na(Fe2+,Mn2+)4(PO4)3, xenophylite Na4(Fe2+,Mn2+)7(PO4)6，一种未知的Na - fe磷酸盐Na2(Fe2+,Mn2+)17(PO4)12，有时还有铬铁矿-2组成。在撞击熔体的所有关联中（硅酸盐部分、孔洞、金属-硫化物聚集体、金属-硫化物泡和磷酸盐球）都发现了晶体的枝状骨骼生长（提供了非常快速淬火的证据）。磷酸钠铁微球的结晶顺序为：铬铁矿-2→铁橄榄石/铁橄榄石→铁橄榄石→铁橄榄石→铁橄榄石。它们被认为是由于Na - fe磷酸盐液体从富含Na， P， Cr和o的均匀Fe-Ni金属硫化物熔体中分离而形成的。Na - ca - mg - fe磷酸盐结晶时没有参与任何液体不混溶过程，直接来自硅酸盐熔体。本文提供了所有研究的磷酸盐和车里雅宾斯克陨石撞击熔体的主要矿物的化学成分和拉曼光谱的数据。

本文章由计算机程序翻译，如有差异，请以英文原文为准。

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来源期刊

Geochemistry International 地学-地球化学与地球物理

CiteScore

1.60

自引率

12.50%

发文量

审稿时长

1 months

期刊介绍： Geochemistry International is a peer reviewed journal that publishes articles on cosmochemistry; geochemistry of magmatic, metamorphic, hydrothermal, and sedimentary processes; isotope geochemistry; organic geochemistry; applied geochemistry; and chemistry of the environment. Geochemistry International provides readers with a unique opportunity to refine their understanding of the geology of the vast territory of the Eurasian continent. The journal welcomes manuscripts from all countries in the English or Russian language.