Primordial water

Primordial water was formed in the primordial (nebular) gas and dust that later collapsed to form the Sun and planets. This dust cloud was rich in hydrogen and oxygen, which are the first and third most abundant elements in the Universe. These elements bound to small dust particles in the cloud. The small size of the dust particles created a large surface area for the attachment of these elements allowing for a large accumulation of hydrogen and oxygen, the building blocks of water. Data suggests a strongly negative deuterium to hydrogen ratio (δD) was added to the Earth during initial formation, during the Hadean eon, via dust particles with adsorbed H2O inherited directly from the protosolar nebula (-870‰). During the early Earth phases the temperature was high, 1000 to 500 K would still allow adsorption of 25% to 300% of Earth's water onto fractal grains during Earth's accretion. Under the high heat and pressure of the Earth's formation, these dust particles and elements were smashed together and formed minerals and in some instances these minerals had H2O inclusion bodies. Chemical models produced by Genda and Ikoma (2008) suggest an increase in the atmospheric D/H (heavy H2)/(light H1) value by a factor of 2 to 9 since Earth's formation.
Primary water or magmatic water
Understanding primordial water is important to understand the origins of primary or magmatic water. Primordial water and its off-spring primary water is the Earth's deep-water reservoir. Originally it was thought that low hydroxyl contents in upper mantle minerals collected near the Earth surface was proof of low solute H2O contents in the source region. However, recent papers have shown that minerals from deep Earth regions with fair to high concentrations of solute hydroxyls can have these reduced through a redox conversion which consumes solute hydroxyls in the matrix of minerals by converting them into peroxy plus molecular H2. The transition zone and lower mantle contain a vast amount of stored water due to high water solubility of its major olivine phase polymorph mineral constituents, wadsleyite and ringwoodite. A compiled table of the elasticity was put together in Zhu et al. (2016), which includes water (wt. %), of different compositions of wadsleyite and ringwoodite. These mantle regions subsequently store a significant amount of primary water solubilized from these deep earth minerals locally. They calculated that the transition zone would contain 3.46 x 1024 g (8640 ppm) of H2O, which corresponds to about 2.5 times of all the Earth's oceans. Based on the hydrous ringwoodite and hydrous wadsleyite; hydrous ringwoodite models the % of the earth’s water in the transition zone is between 28.48% and 17.8% respectively and for the lower mantle, 50.23% and 57.74% respectively. When minerals, rocks, and water are exposed to the Earth's atmosphere, a preferential loss of the lighter hydrogen isotopes occur, driven by thermal atmospheric escape or plasma interactions with gases. It is predicted that water solubilized from primordial water resources would have the same signature. Deuterium is a heavier isotope of hydrogen, with a neutron in its nucleus, and its prevalence compared with that of normal hydrogen serves as a useful fingerprint for tracing an object's history.<ref name="Jewitt and Young" />

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