OSCAR - Oceanographic and Seismic Characterisation of heat dissipation and alteration by hydrothermal fluids at an Axial Ridge

OSCAR - 轴脊热液散热和蚀变的海洋学和地震特征

基本信息

批准号：
NE/I022957/2
负责人：
Chi Tong
金额：
$ 24.26万
依托单位：
University College London
依托单位国家：
英国
项目类别：
Research Grant
财政年份：
2015
资助国家：
英国
起止时间：
2015 至无数据
项目状态：
已结题

来源：
https://gtr.ukri.org/projects?ref=NE%2FI022957%2F2
关键词：
OSCAR Oceanographic Seismic Characterisation heat

项目摘要

The cooling of young oceanic crust is the main physical process responsible for removing heat from the solid Earth to the hydrosphere. Close to the mid-ocean ridge rapid cooling is dominated by hydrothermal circulation of seawater through the porous and fractured basalt crust. This hydrothermal fluid is then discharged into the ocean mainly along the ridge. In this interdisciplinary project we will investigate the effects of this heat loss and hydrothermal circulation in both the solid Earth and the ocean. We will, for the first time, derive an integrated model which will be constrained by geophysical, geological and physical oceanography data that includes pathways in both the solid Earth and the ocean including fluxes through seabed.The most rapid heat exchange occurs close to the fast-spreading ridges, where there are little or no sediments, driven by hydrothermal flow. Cold ocean water enters the fractured basalt in areas on the ridge flanks and flows through the permeable crust becoming super-heated in the proximity of the axial magma chamber. This highly buoyant water ascends rapidly and escapes into the oceans along the ridge axis and is known to form distinct vents called black smokers. Once in the ocean the hot water mixes with the ambient cold water through entrainment and forms a plume that rises to its point of neutral density. The entrainment process may increase the volume of the water in the plume by several orders of magnitude thereby providing a mechanism to heat and lift the densest waters away from the bottom boundary layer. These waters are then more readily available for further mixing and heating as part of the global thermohaline circulation system. The intensity of the hydrothermal fluid flow in the crust decays with distance from the ridge axis because of clogging of the pathways by geochemical alteration products which changes the geophysical properties of the crust and with age, pelagic sediments isolate the fractured basaltic upper crust from the overlaying water preventing direct water exchange. Here conductive heat loss is determined by the thickness and structure of this layer of sediment.The project will acquire an interdisciplinary dataset which integrates physical oceanography and geophysics into a single data acquisition cruise. Using these data we will build and parameterise new integrated models that will provide valuable insight and new constraints of the thermal processes close to ocean ridges that includes a permeable seabed. These data and resultant models will set a new benchmark for integrated multi-physics experiments and will result in a new understanding of the fluid and heat fluxes at ocean ridges and, as importantly a better understanding of what geophysical and oceanographic data actually resolve in the context in an oceanic axial ridge setting, and a predictive model that can be applied to similar ocean ridge systems world-wide.

年轻洋壳的冷却是将热量从固体地球转移到水圈的主要物理过程。靠近洋中脊的快速冷却主要是海水通过多孔且破裂的玄武岩地壳的热液循环。然后，这些热液主要沿着海脊排入海洋。在这个跨学科项目中，我们将研究固体地球和海洋中的热量损失和热液循环的影响。我们将首次推导出一个综合模型，该模型将受到地球物理、地质和物理海洋学数据的约束，其中包括固体地球和海洋中的路径，包括通过海底的通量。最快速的热交换发生在接近快速热交换的地方。 - 扩张的山脊，那里很少或没有沉积物，由热液流驱动。寒冷的海水进入山脊侧面区域的裂隙玄武岩，流过可渗透的地壳，在轴向岩浆房附近变得过热。这种高浮力的水迅速上升并沿着山脊轴线逃逸到海洋中，并形成独特的喷口，称为黑烟囱。一旦进入海洋，热水就会通过夹带与周围的冷水混合，并形成羽流，上升到中性密度点。夹带过程可以使羽流中的水体积增加几个数量级，从而提供一种加热最稠密的水并将其从底部边界层提升的机制。然后，作为全球温盐循环系统的一部分，这些水更容易进一步混合和加热。由于地球化学蚀变产物堵塞了路径，从而改变了地壳的地球物理性质，地壳中热液流的强度随着距山脊轴的距离而衰减，并且随着年龄的增长，远洋沉积物将断裂的玄武岩上地壳与覆盖层隔离开来。水阻止直接水交换。这里的传导热损失由沉积物层的厚度和结构决定。该项目将获取一个跨学科数据集，将物理海洋学和地球物理学集成到单个数据采集巡航中。利用这些数据，我们将建立并参数化新的综合模型，这些模型将为包括可渗透海床在内的海脊附近的热过程提供有价值的见解和新的约束。这些数据和由此产生的模型将为综合多物理实验设定新的基准，并将导致对海脊流体和热通量的新理解，更重要的是更好地理解地球物理和海洋学数据在背景下实际解决的问题在海洋轴脊设置中，以及可应用于全球类似海洋脊系统的预测模型。

项目成果

期刊论文数量（3）

专著数量（0）

科研奖励数量（0）

会议论文数量（0）

专利数量（0）

Magma-hydrothermal interactions at the Costa Rica Rift from data collected in 1994 and 2015

DOI：
10.1016/j.epsl.2019.115991
发表时间：
2020-02
期刊：
Earth and Planetary Science Letters
影响因子：
5.3
作者：
R. Lowell;L. Zhang;M. Maqueda;D. Banyte;V. Tong;R. Johnston;R. Harris;R. Hobbs;C. Peirce;A. Robinson;K. Kolandaivelu
通讯作者：
R. Lowell;L. Zhang;M. Maqueda;D. Banyte;V. Tong;R. Johnston;R. Harris;R. Hobbs;C. Peirce;A. Robinson;K. Kolandaivelu

Magmatic and tectonic segmentation of the intermediate-spreading Costa Rica Rift-a fine balance between magma supply rate, faulting and hydrothermal circulation

中等扩张哥斯达黎加裂谷的岩浆和构造分段——岩浆供给率、断层和热液循环之间的良好平衡