In this paper, we describe the metamorphic conditions of Fe-rich granulite and variations in rare earth elements (REE) between peak garnet porphyroblasts and secondary garnet coronae. The Fe-rich granulites were collected from Vesthaugen, Sør-Rondane Mountains, East Antarctica, and consist mainly of cordierite, garnet, spinel, perthite, K-feldspar, plagioclase, and orthopyroxene or sillimanite. Temperatures estimated from perthitc–mesoperthitic feldspar compositions, experimentally calibrated geothermobarometers and the modeling of P-T pseudosections suggest that the rocks experienced peak ultrahigh-temperature (UHT) metamorphic conditions of 900–950 °C and 5.0 ± 0.5 kbar. Spinel contains quartz inclusions that also provide evidence for UHT metamorphism. Evidence of partial melting is characterized by the presence of leucocratic bands. The second generation of garnet occurs as coronae around spinel, formed during isobaric cooling following the peak conditions of UHT metamorphism. Garnet coronae and garnet porphyroblasts have distinct trace element patterns. Textural evidence and REE geochemistry suggest that the development of garnet coronae was controlled by (1) the REE composition of reactant phases and melt and/or (2) the crystallization of HREE-rich accessory phases (e.g., zircon and monazite) during secondary garnet growth.

中文翻译：

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南极东部 Sør-Rondane 山脉麻粒岩两代石榴石的变质 PT 条件和稀土元素变化

在本文中，我们描述了富铁麻粒岩的变质条件以及峰值石榴石斑状体和次生石榴石日冕之间稀土元素 (REE) 的变化。富铁麻粒岩收集自南极洲东部 Sør-Rondane 山脉的 Vesthaugen，主要由堇青石、石榴石、尖晶石、perthite、钾长石、斜长石和斜方辉石或硅线石组成。从 perthitc – 中长石长石成分、实验校准的地温气压计和 PT 假截面模型估计的温度表明，岩石经历了 900–950 °C 和 5.0 ± 0.5 kbar 的峰值超高温 (UHT) 变质条件。尖晶石含有石英包裹体，也为 UHT 变质提供了证据。部分熔化的证据的特征在于存在白带。第二代石榴石以尖晶石周围的冠冕形式出现，在 UHT 变质达到峰值条件后等压冷却过程中形成。石榴石日冕和石榴石成色素细胞具有不同的微量元素模式。结构证据和 REE 地球化学表明，石榴石冠冕的发展受以下因素控制：（1）反应物相和熔体的 REE 组成和/或（2）次生石榴石中富含 HREE 的辅助相（例如锆石和独居石）的结晶生长。