Abstract
THE author commences at the period when the outer silicate shell of the earth was molten. The primeval magma is regarded as having been practically homogeneous and containing about 60 per cent, of combined silicates. All water was then in the atmosphere, giving a pressure more than 300 times as great as at present. As temperature fell, water and oxygen were absorbed; crust-formation, foundering, and resorption went on for a long period, producing a flat temperature gradient in the liquid. Viscosity eventually rendered further foundering impossible; the crust became permanent, granite developed, and below it the segregated basaltic magma long remained liquid. At this stage the isostatic balance was adjusted. Ore-minerals in large quantity were given off at the surface of the granite; these were denuded and dispersed in sediments and solution. This, with later absorption by intruded basic magma, is assumed to have been instrumental in causing the present erratic distribution of primary ores. All so-called water in magmas is held to exist in combination as hydroxyl with silica not in solution as a gas.
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The Origin of Primary Ore Deposits1. Nature 106, 615 (1921). https://doi.org/10.1038/106615a0
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DOI: https://doi.org/10.1038/106615a0