Here we present major element, trace element, and oxygen isotope data for garnet from an amphibolitized eclogite block from Ring Mountain, Franciscan Complex, California, USA. Garnetite veins 1–5 cm thick are laterally continuous up to 10 m within an Mg-rich blackwall zone of the eclogite block. Complex major and trace element zoning patterns reveal multiple stages of garnet growth in both the matrix and garnetite veins. Similarities in major and trace element zoning between matrix and vein garnet suggest that crystallization of the garnetite veins began toward the end of matrix garnet core growth, and continued throughout the garnet growth history of the rock. Oscillatory zoning in rare-earth elements suggests garnet growth in pulses, with matrix-diffusion-limited growth in between pulses. Oxygen isotope analyses of matrix and vein garnet have a range in δ¹⁸O values of 5.3–11.1 ‰. Differences in δ¹⁸O values of up to ~ 4 ‰ between garnet core and rim are observed in both the matrix and vein; garnet cores range from 9.8 to 11.1 ‰ (median 10.4‰), garnet mantles range from 8.3 to 10.0 ‰ (median 9.7 ‰), and garnet rims range from 5.8 to 7.8 ‰ (median 6.7 ‰). Late-stage vein crystallization appears as a garnet “cement” that fills in a network of small (typically 5–50 µm) garnet cores, and likely crystallized from an amorphous phase. The low δ¹⁸O values of this latest stage of garnet growth are consistent with interaction with serpentinites, and likely represent the physical incorporation of the eclogite block into the serpentinite matrix mélange.

在这里，我们介绍了来自美国加利福尼亚州圣芳济山脉环山的闪石化榴辉岩块体中石榴石的主要元素，微量元素和氧同位素数据。在榴辉岩块的富含镁的黑壁区内，厚度为1–5 cm的石榴石脉横向连续达10 m。复杂的主要元素和微量元素分区模式揭示了石榴石在基质和榴石矿脉中都生长的多个阶段。基质石榴石与脉榴石之间主要和微量元素分区的相似性表明，石榴石脉的结晶始于基质石榴石核心生长的末尾，并在整个石榴石生长历史中一直持续。稀土元素的振荡分区表明石榴石在脉冲中生长，而脉冲之间的基质扩散受限。¹⁸ O值为5.3–11.1‰。在δ差异^18个到〜4‰石榴石芯之间的O值和轮缘在基质和静脉两者都观察到 石榴石芯的范围从9.8到11.1‰（中值10.4‰），石榴石披风的范围从8.3到10.0‰（中值9.7‰），石榴石边缘的范围从5.8到7.8‰（中值6.7‰）。后期静脉结晶以石榴石“水泥”的形式出现，填充了一个小的（通常为5–50 µm）石榴石核的网络，并可能从无定形相中结晶出来。δ低^18个石榴石生长的这个最后阶段的O值是与蛇纹相互作用一致，并且可能代表榴块的物理掺入蛇纹岩基质混杂。