The hydration extent of oceanic lithosphere has been estimated by various methods, the results have shown the hydration degree of the oceanic crust is varying during its life cycle. "The hydration of oceanic lithosphere is composed of two key stages. The initial hydration mainly occurs at mid-ocean ridges, where water percolates into newly formed oceanic crust. The secondary hydration occurs at subduction zones, where water percolates into crust and upper mantle through extensional faults in response to plate bending," Fan Says (see below, Figure 1).
The researchers quantitatively estimated the water input rate for different tectonic settings by integrating the controlling factors including length or width of plate boundary zones, the properties of hydrated lithologic layers, spreading rate at mid-ocean ridges, as well as convergence rate and plate age at subduction zones. The team found that the ridge-transform system, and subduction zones accounts for ~31.2% and ~68.8% of global water input rate, respectively (see below, Figure 2).
The results also indicate that most of the mantle hydration is contributed by the subduction-related process. "These new exciting results add to growing evidence that the secondary hydration at subduction zone is fundamentally essential to plate dynamics and water cycle of the Earth," Jian says.
It is generally accepted that water could influence the plate tectonics and mantle convection, facilitate subduction initiation, and play an important role in earthquake and volcanism. These new results evaluate dual hydration of oceanic lithosphere, and provide important reference for global sea level change, earthquake and volcanic activities, as well as fluid-structure interaction of the Earth.
Research Report:Dual hydration of oceanic lithosphere
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Department of Ocean Science and Engineering, Southern University of Science and Technology, China
Tectonic Science and News
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