Platinum group element (PGE) concentrations have been determined in situ in ordinary chondrite kamacite and taenite grains via laser ablation inductively coupled plasma mass spectrometry (LA‐ICP‐MS). Results demonstrate that PGE concentrations in ordinary chondrite metal (kamacite and taenite) are similar among the three ordinary chondrite groups, in contrast to previous bulk metal studies in which PGE concentrations vary in the order H < L < LL. PGE concentrations are higher in taenite than kamacite, consistent with preferential PGE partitioning into taenite. PGE concentrations vary between and within metal grains, although average concentrations in kamacite broadly agree with results from bulk studies. The variability of PGE concentrations in metal decreases with increasing petrologic type; however, variability is still evident in most type six ordinary chondrites, suggesting that equilibration of PGEs does not occur between metal grains, but rather within individual metal grains via self‐diffusion during metamorphism. The constant average PGE concentrations within metal grains across different ordinary chondrite groups are consistent with the formation of metal via nebular condensation prior to the accretion of ordinary chondrite parent bodies. Post‐condensation effects, including heating during chondrule‐formation events, may have affected some element ratios, but have not significantly affected average metal PGE concentrations.

中文翻译：

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平衡的普通球粒陨石，金云母和钙钛矿中铂族元素的原位分析

铂族元素（PGE）的浓度已通过激光烧蚀电感耦合等离子体质谱法（LA-ICP-MS）在普通球粒陨石kamacite和taenite颗粒中原位测定。结果表明，在三个普通球粒陨石组中，普通球粒陨石金属（高锰铁矿和钙钛矿）中的PGE浓度相似，这与之前的PGE浓度以H <L <LL的顺序变化的散装金属研究相反。钙钛矿中PGE的浓度高于高锰土，这与PGE优先分配到钙钛矿中是一致的。PGE的浓度在金属晶粒之间和金属晶粒内部变化，尽管滑石矿中的平均浓度在很大程度上与大量研究的结果一致。金属中PGE浓度的变化随岩石类型的增加而降低；然而，大多数六种普通球粒陨石的变异性仍然很明显，这表明PGEs的平衡不会在金属晶粒之间发生，而是在变质过程中通过自扩散在单个金属晶粒内部发生。不同普通球粒陨石基团中金属晶粒内的恒定平均PGE浓度与在普通球粒陨石母体积聚之前通过星云凝结形成金属一致。冷凝后的影响，包括在球状晶体形成过程中的加热，可能已经影响了某些元素比率，但并未显着影响平均金属PGE浓度。不同普通球粒陨石基团中金属晶粒内的恒定平均PGE浓度与在普通球粒陨石母体积聚之前通过星云凝结形成金属一致。冷凝后的影响，包括在球状晶体形成过程中的加热，可能已经影响了某些元素比率，但并未显着影响平均金属PGE浓度。不同普通球粒陨石基团中金属晶粒内的恒定平均PGE浓度与在普通球粒陨石母体积聚之前通过星云凝结形成金属一致。冷凝后的影响，包括在球状晶体形成过程中的加热，可能已经影响了某些元素比率，但并未显着影响平均金属PGE浓度。