¹Mingming Zhang, ^1,3Kohei Fukuda, ²Michael J. Tappa, ²William O. Nachlas, ²²Bil Schneider, ⁴Makoto Kimura, ¹Kouki Kitajima, ²Ann M. Bauer, ¹Noriko T. Kita
Geochimica et Cosmochimica Acta (in Press) Link to Article [https://doi.org/10.1016/j.gca.2025.12.056]
¹WiscSIMS, Department of Geoscience, University of Wisconsin–Madison, Madison, WI 53706, USA
²Department of Geoscience, University of Wisconsin–Madison, Madison, WI 53706, USA
³Graduate School of Science, The University of Osaka, 1-1 Machikaneyama-cho, Toyonaka, Osaka 560-0043, Japan
⁴National Institute of Polar Research, Meteorite Research Center, Midoricho 10-3, Tachikawa, Tokyo 190-8518, Japan
Copyright Elsevier

Chondrules, ferromagnesium spherules prevalent in undifferentiated extraterrestrial materials, are the main high-temperature products of the protoplanetary disk. Relict minerals within them directly record precursor compositions and thermal histories, offering critical constraints on the long-debated chondrule heating mechanism. We identified pervasive relict refractory anorthites in Al-rich chondrules (bulk Al2O3 ≥10 wt%, ARCs) from pristine carbonaceous chondrites. These anorthites form rims around relict spinel aggregates or intergrow with high-Ca pyroxene/olivine relics, indicating preferential recycling of anorthite-rich inclusions during outer-disk chondrule heating events over more abundant melilite-rich ones. The wide occurrence of relict anorthite, which can be readily melted or dissolved in chondrule melts, suggests these ARCs were most likely formed by one-time crystallization. Thus, their Al-Mg ages of ∼2.0–2.5 Ma after CAIs imply refractory materials were continuously involved over nearly the entire period of chondrule formation. Additionally, we infer that a portion of co-formed iron-poor ferromagnesium chondrules must have similarly escaped completely remelting by subsequent intense heating events in the same reservoirs. These findings suggest that the intense heating events that lead to carbonaceous chondrule formation are localized and infrequent, aligning with mechanisms like bow shocks, lightning discharges, and impact jetting but not the large-scale nebular shocks.