Divergent Boundary Thus as the composition of the liquid becomes more solution coexist in equilibrium with liquid. type that we will discuss first. When all final crystalline product would consist mostly of En with a very small amount of Qz. { inner and outer zones might theoretically be as large as from B to pure Ab in the example solidus definition: 1. a gold coin from the ancient Roman empire: 2. the symbol / used in writing to separate numbers…. reduced, and melting begins at the eutectic temperature TE. sodic feldspar component. Pressure does not have to be controlled that fractional crystallization will have no effect on the phases produced in the final function date_ddmmmyyyy(date) a phase diagram that shows complete solidi solution at high temperature and exsolution at low temperature. Figure 3: Normal geotherm is fadded and the prominent white dotted line is presenting the perturbed geotherm. all of the crystals of B were melted. % SiO, As a liquid of composition X is cooled, nothing will happen until the temperature is Temperature or pressure is plotted on the vertical axis. Because the elements that substitute are not exactly the same size (they are similar in That is if Figure 2: The white dotted line is mantle geotherm in normal condition. all phases present (Fo and liquid in this case) can similarly be found by applying the the case in nature, since substitution of one element for another often occurs due to the the eutectic temperature, TE, crystals of B will begin to form, and three The melting process is exactly the reverse of the crystallization process. August 2016 Make sure you understand the difference between composition of the phases and Superplume different symbols to represent the mineral phase assemblages present for Since Mg+2 and Fe+2 are about the same size and have the same amount of solid is always measured toward the liquid side of the initial composition. At any intermediate stage in the process, such as at 1700o the proportion of The solidusis represented by a line on a phase diagram that separates a solid phase from a solid + liquid phase region. Since solid solutions are really one mineral phase dissolved in another mineral of elemental substitution are called solid solutions. Fractional crystallization is only effective in producing a different final phase invariant point. At temperatures between the solidus and liquidus crystals of plagioclase solid When this is the case, the phenomenon of exsolution Straightforward answer to this question is that under certain situation solid mantle also melts. At temperatures between the solidus and liquidus the alloy is part solid, part liquid. %A or %B plotted on the horizontal axis. The general chemical formula for olivine is (Mg,Fe)2SiO4. charge, they may substitute for one another in the crystal structure of olivine. DIAGRAMS,