Transport experiments, sediment cores

How water is transported into the mantle and the depths to which it can be carried have been investigated in high-pressure experiments. In brief, these show that whilst hydrous phases in basalt and subducted sediment can transport water down to the top of the transition zone at about 410 km, hydrous phases in mantle peridotite are capable of transporting water even deeper, certainly into the lower mantle and maybe into the core. 

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