Decarbonation, serpentinization, abiogenic methane, and extreme pH beneath the Mariana forearc Posted on July 1, 2014 by UHNAI Webmaster in Mottl, M.J., C.G. Wheat, and P. Fryer (). Decarbonation, serpentinization, abiogenic methane, and extreme pH beneath the Mariana forearc. , 85,