Trace Element Mobility in Subducted Marble and Associated Eclogite: Constraints from UHP Rocks in the Shuanghe Area, Central-East China
Trace Element Mobility in Subducted Marble and Associated Eclogite: Constraints from UHP Rocks in the Shuanghe Area, Central-East China
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DOI：
10.1007/s12583-022-1692-3
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发表时间：
2024-02
影响因子：
3.3
通讯作者：
Xingao Hou;Zhiqiang Yu;Shefa Chen;Lei Liu;Yilin Xiao
中科院分区：
文献类型：
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作者：
Xingao Hou;Zhiqiang Yu;Shefa Chen;Lei Liu;Yilin Xiao
为了揭示大陆俯冲带UHP变质沉积岩中元素的流动性，对大别山UHP代表性地区的连续剖面进行了主微量元素组成研究。在岩性接触带中，大理岩和榴辉岩中K、Ca、LREE和LILE含量均向接触带方向呈现不同程度的下降趋势，说明大理岩及其伴生榴辉岩可以释放大量的K、Ca和少量的LILEs和LREE。大理岩和榴辉岩的主要钛相均为钛矿。在榴辉岩中偶尔可以看到围绕金红石的钛矿边缘。大理岩和榴辉岩中Ti和HFSE的含量表现出良好的耦合关系，表明大量Ti和HFSE从榴辉岩向大理岩迁移，这与熔融介质的容量一致。大理岩中金红石和钛矿的Nb/Ta比值变化相对有限（12.9 ~ 16.2），与榴辉岩中钛矿的Nb/Ta比值变化相似（14.2 ~ 16.7），说明大理岩中的金红石和钛矿来源于榴辉岩中Ti和hfse的短距离迁移。根据前人报道的p - tpath和峰值变质的温度和压力条件，与大理岩伴生的榴辉岩可能由于碳酸盐矿物的加入而在俯冲带没有形成超临界流体。
In order to decipher element mobility in UHP meta-sedimentary rocks in the continental subduction zone, major and trace element compositions are investigated for a continuous profile from a representative UHP region in the Dabie Mountains. Among the lithologic contact zone, contents of K, Ca, LREE, and LILE exhibit varying degrees of downward trends in both marble and eclogite toward the contact zone, indicating that marble and their associated eclogite can release a large amount of K, Ca, and a small number of LILEs and LREEs. Titanite is the main Ti phase in both marble and eclogite. Titanite rims around rutile can occasionally be seen in eclogite. Contents of Ti and HFSE exhibit a well-coupled relation among marble and eclogite, indicating that substantial Ti and HFSEs were migrated from eclogite to marble, in accord with the capacity of a melt medium. Rutiles and titanites in marble exhibit a relatively limited variation in Nb/Ta ratios (12.9–16.2), similar to those of titanites in eclogite (14.2–16.7), which demonstrates that rutiles and titanites in marble were sourced from eclogite because of short-distance migrations of Ti and HFSEs. According to theP-Tpath and the temperature and pressure conditions of the peak metamorphism reported by previous studies, the eclogite associated with marble may not form supercritical fluids in the subduction zone because of the addition of carbonate minerals.