Publications
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A linear programming and least squares computer method for solving petrologic mixing problems A linear programming and least squares computer method for solving petrologic mixing problems
Problems of petrologic mixing have been solved using a two-stage computer-based calculation. First, linear programming is used to obtain an approximate solution and to identify non-negative solution values. Then a conventional least squares calculation is performed using the analyses represented by non-negative solution values as input to yield an optimum set of solution values. The...
Authors
Thomas L. Wright, Patrick C. Doherty
Radiogenic heat production of contrasting magma series: Bearing on interpretation of heat flow Radiogenic heat production of contrasting magma series: Bearing on interpretation of heat flow
Variation in radiogenic heat production of rocks of diverse magma series (representative of calcic, calc-alkalic, alkali-calcic, and alkalic petrographic provinces on a worldwide basis) is better correlated with some form of magmatic differentiation index, rather than simply with potassium content alone as commonly supposed. The “lime-alkali” (Peacock) index generally gives the best...
Authors
Robert I. Tilling, David Gottfried, F. C. W. Dodge
Caldera collapse in the Galápagos Islands, 1968 Caldera collapse in the Galápagos Islands, 1968
The summit caldera of Isla Fernandina, a large, uninhabited basaltic shield volcano, was further enlarged by 1 to 2 km3 in June 1968. A small quake and large vapor cloud on 11 June were followed 4 hours later by a remarkable volcanic ash cloud and, after another hour, by a major explosion recorded at infrasonic stations throughout the hemisphere. Seismic activity increased to a peak on...
Authors
T. Simkin, K. A. Howard