Integrated Fluid Inclusion and P–T Dataset from the Himalayan Orogen: Recalculated Fluid Properties and Isochore Constraints with Implications for Fluid Evolution and the Global Carbon Cycle

This dataset represents a comprehensive compilation of mineral P–T conditions and fluid inclusion (FI) data from all lithotectonic units of the Himalayan orogen, significantly enhancing our understanding of this intricate geological system. It encompasses data from the Sub-, Lesser-, Higher-, and Tethyan Himalaya, as well as the Indus–Tsangpo Suture Zone and its associated magmatic arc. The compilation integrates previously published microthermometric results—eutectic temperature (Te), final ice-melting temperature (Tm,ice), CO2 homogenization temperature (ThCO2), and total homogenization temperature (Th)—to recalculate the salinity, density, and molar volume of trapped fluids using updated equations of state and modern fluid inclusion programs. Isochores have been constructed for each lithotectonic unit to infer the pressure–temperature (P–T) conditions of fluid entrapment, maximum burial depths, and metamorphic pathways.<br>The recalculated data offer a unified foundation for intercomparison across the orogen, facilitating a quantitative reconstruction of Himalayan fluid evolution through successive tectonometamorphic stages—from early diagenesis and subduction-related metamorphism to crustal thickening, partial melting, and exhumation. The results indicate that carbonic and aqueous–carbonic fluids are prevalent throughout the orogen, extending from the Lesser Himalayan metasediments to the ultrahigh-pressure eclogites of the Tso-Morari Complex. This continuous presence and movement of CO₂-bearing fluids during the orogenic cycle underscore the dynamic nature of the Himalayan orogen. Furthermore, the identification of N₂-rich inclusions in UHP rocks emphasizes the involvement of reduced nitrogen fluids in deep subduction and their potential role in redox buffering and crust–mantle volatile exchange.<br>Collectively, this dataset illustrates that CO₂- and N₂-bearing fluids were not only present but also served as key agents in metamorphic devolatilization, rock weakening, and carbon transfer throughout the Himalayan evolution. Their widespread occurrence suggests that the Himalaya operated as a dynamic trans-crustal fluid system capable of both releasing and sequestering carbon over geological timescales. These findings establish a crucial link between the fluid history of the Himalayan orogen and the global carbon cycle, emphasizing the role of collisional mountain belts as pivotal regulators of atmospheric CO₂ through deep Earth degassing and surface weathering feedbacks.

本数据集全面汇编了喜马拉雅造山带所有岩石构造单元的矿物温压条件与流体包裹体（fluid inclusion, FI）数据，极大深化了对这一复杂地质系统的认知。数据集涵盖亚喜马拉雅、小喜马拉雅、大喜马拉雅、特提斯喜马拉雅，以及印度河-雅鲁藏布缝合带及其相关岩浆弧的相关数据。本次汇编整合了已发表的显微测温结果——共结温度（eutectic temperature, Te）、最终融冰温度（final ice-melting temperature, Tm,ice）、CO₂均一温度（CO₂ homogenization temperature, ThCO2）与总均一温度（total homogenization temperature, Th），并借助更新的状态方程与现代流体包裹体模拟软件，重新计算了捕获流体的盐度、密度与摩尔体积。研究人员为每个岩石构造单元构建了等容线，以此反演流体捕获时的温压（pressure–temperature, P–T）条件、最大埋藏深度与变质作用路径。
重新计算得到的数据为整个造山带的对比研究提供了统一基础，助力定量重建喜马拉雅地区流体在连续构造-变质阶段的演化历程——从早期成岩作用、俯冲相关变质作用，到地壳增厚、部分熔融与折返过程。研究结果显示，碳酸质流体与水-碳酸质流体遍布整个造山带，分布范围从小喜马拉雅变质沉积岩延伸至措莫拉里杂岩体的超高压（ultrahigh-pressure, UHP）榴辉岩。造山旋回中含CO₂流体的持续存在与运移，凸显了喜马拉雅造山带的动力学特性。此外，在超高压岩石中识别出富N₂包裹体，证实了还原态氮流体参与了深部俯冲过程，且其可能在氧化还原缓冲与壳幔挥发分交换中发挥了重要作用。
综合来看，本数据集表明，在喜马拉雅演化全过程中，含CO₂与N₂的流体不仅广泛存在，更是变质脱挥发作用、岩石弱化与碳迁移的关键媒介。这类流体的广泛分布说明，喜马拉雅是一个动态的跨地壳流体系统，能够在地质时间尺度上实现碳的释放与封存。本研究结果为喜马拉雅造山带流体演化历史与全球碳循环建立了关键关联，强调了碰撞造山带通过深部地球脱气与地表风化反馈，成为大气CO₂的关键调控者的重要作用。