| 大洋岩石圈板块俯冲构造背景下流体的地质作用 |
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| 引用本文： | 徐婕,翟世奎,于增慧,王轲,张侠.大洋岩石圈板块俯冲构造背景下流体的地质作用[J].海洋学报,2021,43(1):27-43. |
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| 作者姓名： | 徐婕 翟世奎 于增慧 王轲 张侠 |
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| 作者单位： | 1.中国海洋大学 海洋地球科学学院，山东 青岛 266100 |
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| 基金项目： | 国家重点基础研究发展计划(2013CB429702)。 |
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| 摘 要： | 地幔中存在着大量的“水”(存在形式:H2O、H+和(HO)?)已是不争的事实，这些“水”既可以以流体或熔体的形式存在，又可以存在于含水矿物、名义上的无水矿物和致密含水镁硅酸盐中。在本文中，“流体”是指以水为主体包括溶解于水中或随水迁移的元素和化合物。在俯冲带的地震作用、地幔部分熔融、岩浆作用以及海底热液活动等重大地质作用过程中，流体都发挥着重要的作用。俯冲带是水化了的大洋岩石圈板块俯冲进入地球深处的关键部位，也是壳幔相互作用的重要地带。在俯冲带，流体随俯冲的岩石圈板块进入地球深部，部分在挤压和摩擦热的作用下脱逸俯冲的岩石圈板块，连同岩石矿物变质所产生的水进入上覆地幔楔，从而降低上覆地幔物质的熔点，产生岩浆；岩浆上升一方面加热了沿裂隙或物质间隙下渗的海水，另一方面也会因岩浆冷却产生岩浆作用后期热液流体，这些加热的下渗海水和岩浆作用后期流体构成了现代海底热液活动的物质基础；海底热液活动不仅将大量地下元素或物质输入大洋水体从而影响了大洋海水的物质组成及生态环境，而且在海底形成了具有重要经济价值的热液多金属矿体。因此，流体是贯穿板块俯冲及其所产生的各种重要地质作用过程的介质，从而成为研究这些重要地质作用的示踪剂。本文在分析了大洋岩石圈板块俯冲构造背景下流体的主要地质作用过程的基础上，探讨了流体在俯冲带地震发生机制、岩浆作用过程、现代海底热液活动模式及俯冲带流体成矿作用等方面的作用，并进一步提出近期研究工作应主要集中在4个方面:(1)进一步准确地定量评估通过板块俯冲作用进入地球深部的“流体”通量，为最终解决全球地球化学或物质循环问题作出贡献；(2)全面、准确地描述俯冲作用中流体的物理和化学行为，建立俯冲带流体地质作用的理论模型；(3)充分利用现代化的测试分析手段，重点获取矿物原位微区分析、矿物流体包裹体物理化学指标测试、稳定和放射性同位素分析等方面的精细准确数据，用于查明当前取样观测手段无法触及的地下深处物质状态和作用过程；(4)发展数值模拟技术，建立俯冲带流体地质作用的理论模型。
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| 关 键 词： | 流体地质作用 俯冲带 研究现状 近期研究方向 |
| 收稿时间： | 2020-02-19 |
Geological processes of fluids in the oceanic lithosphere subduction |
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| Xu Jie,Zhai Shikui,Yu Zenghui,Wang Ke,Zhang Xia.Geological processes of fluids in the oceanic lithosphere subduction[J].Acta Oceanologica Sinica (in Chinese),2021,43(1):27-43. |
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| Authors: | Xu Jie Zhai Shikui Yu Zenghui Wang Ke Zhang Xia |
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| Institution: | 1.College of Marine Geosciences, Ocean University of China, Qingdao 266100, China2.Key Lab of Submarine Geosciences and Prospecting Techniques, Ministry of Education, Qingdao 266100, China |
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| Abstract: | It is no doubt that there is plenty of “water” (existential form: H2O, H2 and (HO)?) existing in the mantle which can either exist in the form of fluids and melts or exist in aqueous minerals, nominally anhydrous minerals (NAMs) and dense hydrous Mg-silicates (DHMS). In this paper, “fluid” mainly refers to water which includes elements and compounds that dissolved in or migrated with it. Fluids, mainly consisting of water, play important roles in major geologic processes such as subduction zone earthquakes, mantle partial melting, magmatism and submarine hydrothermal activities. The subduction zone is a key place where the hydrated oceanic lithospheric plate subducts into the earth’s depth. And it is also an important zone of crust-mantle interaction. In the subduction zone, fluids are carried into the deep earth by the subducting lithospheric plate, part of the fluids are released into the overlying mantle wedge by extrusion, frictional heating and metamorphism, thereby lowering the melting point of mantle materials and causing magmatism; on the one hand, the ascending magma heats seawater that penetrates through cracks or rifts; on the other hand, the heated seawater and post-magmatic fluids generated by magma cooling compose the material basis of modern submarine hydrothermal activities; submarine hydrothermal activities not only affect the material composition of ocean water and ecological environment by importing a large number of underground elements or substances into ocean water, but also lead to the formation of hydrothermal polymetallic ore deposits with important economic value. Therefore, the fluid is a medium in the plate subduction process and the various important geological processes caused by it, thus it is a tracer to study these important geological processes. Based on the analysis of the main geological processes of fluids in the oceanic lithosphere subduction, this paper discussed the roles of fluids in earthquake mechanism, magmatic processes, modern submarine hydrothermal activities and subduction zone fluid mineralization. Furthermore, it is suggested that the recent research work should focus on these four aspects: (1) Making the assessment of the fluid flux subducted into the deep earth more accurate to solve global geochemical or material circulation problems. (2) Describing physical and chemical behaviors of fluids in plate subduction comprehensively and accurately, establishing theoretical models of fluid geological processes in subduction zones. (3) Making full use of modern tests and analysis methods, and obtaining accurate data in terms of in-situ analysis of minerals, testing physical and chemical indexes of fluid inclusions in minerals, stable and radioactive isotope analysis, etc., so as to find out the state and process of substances deep underground which can not be reached by current sampling and observation methods. (4) Developing numerical simulation technique to establish theoretical models of geological processes of fluids in subduction zones. |
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| Keywords: | geological processes of fluids subduction zone research actuality recent research direction |
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