Cl, O, and H stable isotope compositions of variably hydrated North American SCLM xenoliths

The sub-continental lithospheric mantle (SCLM) beneath the Colorado Plateau is enriched in volatile elements likely due to interaction with fluids or melts derived from the subducted Farallon plate. This dataset examines bulk rock chlorine (δ37Cl) and hydrogen (δD) isotope compositions, bulk water content, and oxygen (δ18O) isotope compositions of clinopyroxene mineral separates from variably hydrated SCLM xenoliths from the Navajo Volcanic Field on the central Colorado Plateau and from anhydrous SCLM xenoliths from the southern Rio Grande Rift. These stable isotope ratios suggest that the metasomatic fluid source had elevated chlorine and hydrogen isotope ratios relative to the mantle, but lower oxygen isotope ratios. The most likely source of such stable isotope signatures is subducted gabbroic altered oceanic crust in the subducted Farallon plate. This finding has implication on the retention of volatile elements in subducted oceanic crust and on Cl isotope variation in the deep mantle.科罗拉多高原下方的大陆下岩石圈地幔（sub-continental lithospheric mantle, SCLM）富集挥发分元素，其成因大概率为与源自俯冲法拉隆板块的流体或熔体发生相互作用。本数据集针对科罗拉多高原中部纳瓦霍火山场的不同水化程度SCLM捕虏体，以及里奥格兰德裂谷南部的无水SCLM捕虏体中的单斜辉石单矿物试样，分析了全岩氯（δ37Cl）与氢（δD）同位素组成、全岩含水量，以及单斜辉石单矿物试样的氧（δ18O）同位素组成。上述稳定同位素比值表明，交代流体源相较于地幔具有更高的氯与氢同位素比值，但氧同位素比值更低。此类稳定同位素特征最可能的来源为俯冲法拉隆板块内部的蚀变辉长岩洋壳。该发现对于俯冲洋壳中挥发分元素的滞留过程，以及深地幔内的氯同位素变化均具有重要启示意义。