Each of the halogens constrains a different aspect of volatile cycling in the solid Earth. F is moderately incompatible in the mantle and has a low mobility at Earth's surface, meaning that it is preferentially retained in the mantle and continental crust. In contrast, Cl, Br, and I are strongly incompatible and highly soluble. Chloride is the dominant anion in seawater and many geofluids and a major component of evaporite minerals. Br and I are essential for life and significantly incorporated into organic matter that accumulates in marine sediments. Surficial fluids circulated into continental and oceanic crust incorporate surface-derived halogens into alteration minerals. As a result, subducting slabs and arc lavas are weakly enriched in F and strongly enriched in Cl, Br, and I. Subduction has maintained mantle Cl and Br concentrations at relatively constant levels since Earth's early differentiation, but mantle I/Cl has decreased over time. ▪Halogen abundances on the early Earth were affected by I partitioning into Earth's core and possible loss of hydrophilic Cl, Br, and I in an early formed ocean.▪Halogens are powerful tracers of subduction zone processes on the modern Earth, with Cl, Br, and I having a dominantly subducted origin in Earth's mantle.▪The deep subduction cycles of Cl, Br, and I are more similar to that of H2O than they are to F, but the geochemical cycle of each halogen differs in detail.▪Halogen abundance ratios and stable isotope ratios vary systematically in Earth's surface reservoirs, meaning that halogens are powerful tracers of geological fluids and melts.

中文翻译：

---

固体地球中的卤素循环


每一种卤素都限制了固体地球中挥发性循环的不同方面。F 在地幔中处于中等不相容状态，在地球表面的迁移率较低，这意味着它优先保留在地幔和大陆地壳中。相比之下，Cl、Br 和 I 是极不相容且高度可溶的。氯化物是海水和许多地质流体中的主要阴离子，也是蒸发矿物的主要成分。Br 和 I 对生命至关重要，并显着掺入海洋沉积物中积累的有机物中。循环到大陆和海洋地壳中的表面流体将表面衍生的卤素掺入蚀变矿物中。因此，俯冲板块和弧形熔岩在 F 中含量较弱，而在 Cl、Br 和 I 中含量较强。自地球早期分化以来，俯冲作用一直将地幔 Cl 和 Br 浓度维持在相对恒定的水平，但地幔 I/Cl 随着时间的推移而下降。▪卤素在早期地球上的丰度受到 I 分裂到地核以及亲水性 Cl、Br 和 I 在早期形成的海洋中可能损失的影响。▪卤素是现代地球上俯冲带过程的强大示踪剂，其中 Cl、Br 和 I 在地幔中具有主要俯冲起源。▪Cl 的深部俯冲循环， Br 和 I 与 H2O 的相似程度高于与 F 的相似性，但每种卤素的地球化学循环在细节上有所不同。▪卤素丰度比和稳定同位素比在地球表面储层中系统性地变化，这意味着卤素是地质流体和熔体的强大示踪剂。