the water appears locked in moisture-containing rocks...
What do you suppose that word that begins with "L" means, Jz? And at what temperature do you suppose the water and rock 30 km beneath the Himilayas is?
"The Christian church, in its attitude toward science, shows the mind of a more or less enlightened man of the Thirteenth Century. It no longer believes that the earth is flat, but it is still convinced that prayer can cure after medicine fails." H L Mencken
The early CO2 on earth partly got converted to carbohydrates in all the plant like on earth. A bunch more was captured to form limestone and dolomite, which make up a great deal of all the sedimentary rock in the crust. Gradually by either method. Millions to billions of years.