Flowage Differentiation

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Science  10 Jul 1964:
Vol. 145, Issue 3628, pp. 150-153
DOI: 10.1126/science.145.3628.150


Flowage differentiation is an experimentally demonstrable process capable of causing crystal and chemical fractionation in nature. It is a mechanism for forming olivine-rich rocks in a vertical or steeply dipping position without prior concentration on a flat floor. It explains the field observation that the chilled margin of a mafic intrusion may not be a representative sample of the average composition of the parent magma. In contrast to previous hypotheses of origin for composite dikes, it causes fractionation during and as a result of a single movement of magma rather than by multiple injections.