Oxygen planetary differentiation

Such a measurement can tell us about the chemical evolution of oxygen, such as whether the isotopes differentiated via a thermal cycle in which lighter leO fractionates from the heavier lsO, much as Vostok ice-core oxygen ratios reveal the Earth s prehistoric climate. From this fixed point of the Sun s oxygen ratios, we can then trace the history of water in other planetary bodies since their birth in the solar nebulae through the subsequent cometary bombardment [13]. In NASA s search for water on the Moon, important for the establishment of a future Moon base, such isotopic ratios will determine whether the water is a vast mother lode or just a recent cometary impact residue. 

In terms of oxygen isotopes, on a planetary scale, the isotopic (and chemical) composition of the ocean is dominated by the competition between two major processes exchange between mantle-derived reservoirs at midocean ridges and the exchange with silicate rocks at low temperature due to chemical weathering. The change in the isotopic composition of the ocean can be described by a differential eqiration of the form ... 

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