Abstract Lawsonite is an abundant hydrous mineral in oceanic crust, sediments, and metasomatic rocks at depths of ~45 to 300 km in most subduction zones, but it is rarely preserved in the geologic record because it commonly transforms to epidote and other minerals during prograde or retrograde metamorphism. Owing to the significance of lawsonite for water and element cycling in subduction zones, occurrences of fresh lawsonite in blueschist and, more rarely, eclogite provide important opportunities to determine lawsonite composition, zoning, and inclusion suites and to use this information to reconstruct reaction history during subduction and exhumation. In this review, we use new and published data to document lawsonite composition in eight of the nine known lawsonite eclogite localities in which fresh lawsonite coexists with garnet + omphacite in the rock matrix, as well as the composition of lawsonite inclusions in six of seven known sites in which lawsonite occurs only as inclusions in garnet in eclogite-facies rocks that lack matrix lawsonite. As lawsonite blueschist is much more common than lawsonite eclogite, we survey the composition of lawsonite in representative localities of blueschist, including blueschist associated with eclogite (lawsonite-bearing, epidote-bearing), and blueschist not associated with eclogite at current exposure levels. Included in this review are metabasaltic rocks, silica- and carbonate-rich metasedimentary rocks, metasomatic rocks, and lawsonite-rich veins. This dataset demonstrates that lawsonite composition is a sensitive indicator of reaction history during subduction and exhumation, and specifically of fluid–rock interaction, with implications for element cycling in subduction zones. Furthermore, most exhumed lawsonite eclogite records slab-surface conditions that correspond to the location where the slab-mantle interface transitions from decoupled to coupled, and therefore provides key insights into the thermal history and dynamics of subduction zones.

中文翻译：

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作为俯冲过程示踪剂的劳森石成分和分区：全球综述

摘要 劳森石是一种丰富的含水矿物，存在于大部分俯冲带约 45 至 300 公里深处的洋壳、沉积物和交代岩中，但它在地质记录中很少被保存，因为它通常在前进或退化过程中转化为绿帘石和其他矿物。逆行变质。由于硬柱石对俯冲带中水和元素循环的重要性，蓝片岩中新鲜硬柱石和榴辉岩的出现提供了重要的机会来确定硬柱石成分、分带和包裹体套件，并利用这些信息重建反应过程中的反应历史。俯冲和掘出。在这次审查中，我们使用新的和已发布的数据来记录 9 个已知的硬柱石榴辉岩产地中的 8 个产地的硬柱石成分，其中新鲜硬柱石与岩石基质中的石榴石 + 绿辉石共存，以及七个已知产地中的六个产地的硬柱石内含物成分仅作为榴辉岩相岩石中的石榴石中的包裹体出现，而缺乏基体硬柱石。由于硬柱石蓝片岩比硬柱石榴辉岩更常见，我们调查了蓝片岩代表性产地的硬柱石成分，包括与榴辉岩相关的蓝片岩（含硬柱石、含绿帘石），以及在当前暴露水平下与榴辉岩无关的蓝片岩。本综述包括变玄武岩、富含二氧化硅和碳酸盐的变质沉积岩、交代岩和富含硬镁石的矿脉。该数据集表明硬柱石成分是俯冲和折返过程中反应历史的敏感指标，特别是流体-岩石相互作用，对俯冲带中的元素循环有影响。此外，大多数出土的硬柱石榴辉岩记录了与板片-地幔界面从解耦过渡到耦合位置的板片表面条件，因此提供了对俯冲带的热历史和动力学的关键见解。