Mineralogically zoned chondrules are a common chondrule type in chondrites. They consist of olivine cores, surrounded by low‐Ca pyroxene rims. By serial sectioning porphyritic chondrules from carbonaceous, ordinary, and enstatite chondrites, we demonstrate that the 2‐D textural appearances of these chondrules largely depend on where they are cut. The same chondrule may appear as a porphyritic pyroxene (PP) chondrule when sectioned through the low‐Ca pyroxene rim, and as a porphyritic olivine‐pyroxene (POP) or porphyritic olivine (PO) chondrule when sectioned close or through its equator. Chondrules previously classified into PP/POP/PO chondrules might therefore not represent different types, but various sections through mineralogically zoned chondrules. Classifying chondrule textures into PP, POP, and PO has therefore no unequivocal genetic meaning, it is merely descriptive. Sectioning effects further introduce a systematic bias when determining mineralogically zoned chondrule fractions from 2‐D sections. We determined correction factors to estimate 3‐D mineralogically zoned chondrule fractions when these have been determined in 2‐D sections: 1.24 for carbonaceous chondrites, 1.29 for ordinary chondrites, and 1.62 for enstatite chondrites. Using these factors then shows that mineralogically zoned chondrules are the dominant chondrule type in chondrites with estimated 3‐D fractions of 92% in CC, 52% in OC, and 46% in EC.

中文翻译：

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斑状软骨的剖面效果：对PP / POP / PO分类的影响以及纠正矿物学上划分的软骨的模态丰度

矿物学上划分的球粒陨石是球粒陨石中的一种常见的球粒陨石类型。它们由橄榄石核组成，被低钙的辉石边缘包围。通过从碳质，普通和顽辉岩球粒岩中依次划分斑状球粒岩，我们证明了这些球粒岩的二维纹理外观很大程度上取决于它们的切割位置。通过低Ca辉石边缘切开时，相同的软骨可能显示为卟啉辉石（PP）软骨切面，如果通过接近或通过其赤道切开，则可能显示为卟啉的橄榄石-辉石（POP）或卟啉的橄榄石（PO）软骨素。因此，先前归类为PP / POP / PO软骨的软骨可能并不代表不同的类型，而是通过矿物学划分的软骨的各个部分。将软骨规则纹理分为PP，POP，因此，PO没有明确的遗传意义，仅是描述性的。在确定二维剖面中按矿物学划分的软骨成分时，剖面效应进一步引入了系统性偏差。当确定了二维剖面中确定的3D矿物学成矿带状碎屑分数时，我们确定了校正因子：碳质球粒陨石为1.24，普通球粒陨石为1.29，顽辉陨石为1.62。然后，利用这些因素可以发现，按矿物学特征划分的球粒状陨石是球粒陨石中的主导球粒状类型，估计3D分量在CC中为92％，在OC中为52％，在EC中为46％。当确定了二维剖面中确定的3D矿物学成矿带状碎屑分数时，我们确定了校正因子：碳质球粒陨石为1.24，普通球粒陨石为1.29，顽辉陨石为1.62。然后，利用这些因素可以看出，按矿物学特征划分的球状陨石是球粒陨石中的主要球状陨石类型，估计3D分量在CC中为92％，在OC中为52％，在EC中为46％。当确定了二维剖面中确定的3D矿物学成矿带状碎屑分数时，我们确定了校正因子：碳质球粒陨石为1.24，普通球粒陨石为1.29，顽辉陨石为1.62。然后，利用这些因素可以发现，按矿物学特征划分的球粒状陨石是球粒陨石中的主导球粒状类型，估计3D分量在CC中为92％，在OC中为52％，在EC中为46％。