Chondrules are sub-millimetric spheroids that are ubiquitous in chondrites and whose formation mechanism remains elusive. Textural and oxygen isotopic characteristics of chondrules in carbonaceous chondrites (CCs) suggest that they result from the recycling of isotopically heterogeneous early-condensed precursors via gas-melt interactions. Here, we report high-resolution X-ray elemental maps and in situ O isotopic analyses of FeO-poor, olivine-rich chondrules from ordinary chondrites (OCs) to compare the conditions of chondrule formation in these two main classes of chondrites. OC chondrules show minor element (e.g., Ti, Al) zonings at both the chondrule and individual olivine grain scales. Considering the entire isotopic data set, our data define a mass-independent correlation, with olivine grains showing O isotopic variations spanning more than 40 ‰. Though ¹⁶O-rich relict olivine grains were identified in OC chondrules, they are much less abundant than in CC chondrules. They appear as two types: (i) those with low minor element abundances and Δ¹⁷O < −15 ‰ and (ii) those with varying minor element abundances and less negative Δ¹⁷O values averaging −5.5 ‰. The host olivine grains exhibit mass-dependent O isotopic variations within individual chondrules.

Our results reveal that similar processes (precursor recycling and interactions between chondrule melts and a SiO- and Mg-rich gas) established the observed features of OC and CC chondrules. The mass-dependent isotopic variations recorded by host olivine grains result from kinetic effects induced by complex evaporation/recondensation processes during the gas-melt interactions. This suggests that OC chondrules formed through enhanced recycling processes, in good agreement with the lower abundances of relict olivine grains in OC chondrules compared to CC chondrules. We use the Δ¹⁸O = δ¹⁸O − δ¹⁷O parameter to demonstrate that there is no genetic relationship between CC and OC chondrules, suggesting limited radial transport in the protoplanetary disk. Finally, to the first order, the Δ¹⁸O−Δ¹⁷O diagram may allow the non-carbonaceous vs. carbonaceous origin of a given chondrule to be deciphered.

球粒是亚毫米球体，在球粒陨石中无处不在，其形成机制仍然难以捉摸。碳质球粒陨石 (CCs) 球粒的结构和氧同位素特征表明，它们是由同位素异质早期凝聚前体通过气体-熔融相互作用回收的结果。在这里，我们报告了高分辨率 X 射线元素图和原位对来自普通球粒陨石 (OC) 的贫铁、富含橄榄石的球粒进行 O 同位素分析，以比较这两种主要球粒陨石中球粒形成的条件。OC 球粒在球粒和单个橄榄石晶粒尺度上显示出微量元素（例如，Ti、Al）分带。考虑到整个同位素数据集，我们的数据定义了一种与质量无关的相关性，橄榄石颗粒显示 O 同位素变化范围超过 40 ‰。尽管在 OC 球粒中发现了¹⁶个富含 O 的残存橄榄石粒，但它们的数量远不如 CC 球粒中的丰富。它们表现为两种类型：(i) 微量元素丰度低且 Δ ¹⁷ O < -15 ‰ 和 (ii) 微量元素丰度不同且负 Δ ¹⁷较小的那些O 值平均为 -5.5 ‰。寄主橄榄石颗粒在单个球粒内表现出依赖于质量的 O 同位素变化。

我们的结果表明，类似的过程（前体回收和球粒熔体与富含 SiO 和 Mg 的气体之间的相互作用）建立了观察到的 OC 和 CC 球粒特征。寄主橄榄石颗粒记录的与质量有关的同位素变化是由气体-熔体相互作用过程中复杂的蒸发/再冷凝过程引起的动力学效应引起的。这表明 OC 球粒是通过增强的再循环过程形成的，这与 OC 球粒中残存橄榄石粒的丰度低于 CC 球粒的丰度非常吻合。我们使用 Δ ¹⁸ O = δ ¹⁸ O − δ ¹⁷O 参数证明 CC 和 OC 球粒之间没有遗传关系，表明原行星盘中的径向运输有限。最后，对于一阶，Δ ¹⁸ O-Δ ¹⁷ O 图可能允许非碳质与。要破译的给定球粒的碳质起源。