Adcumulates

Adcumulates form when the intercumulus liquid is similar in composition to cumulate crystals and results in additional growth of cumulus grains of similar composition. Adcumulates are essentially monomineralic, although the growth boundary between the original cumulate grain and later adcumulus growth is recognizable. The exact way in which the cumulus crystals became enlarged by material of similar composition is still not certain, but it must have taken place at the same temperature as the formation of the cumulus crystals because of the similarity in the solid solution composition. By such growth the intercumulus liquid would gradually be pushed out.

Bibliography

• Cox et al. (1979): The Interpretation of Igneous Rocks, George Allen and Unwin, London.
• Howie, R. A., Zussman, J., & Deer, W. (1992). An introduction to the rock-forming minerals (p. 696). Longman.
• Le Maitre, R. W., Streckeisen, A., Zanettin, B., Le Bas, M. J., Bonin, B., Bateman, P., & Lameyre, J. (2002). Igneous rocks. A classification and glossary of terms, 2. Cambridge University Press.
• Middlemost, E. A. (1986). Magmas and magmatic rocks: an introduction to igneous petrology.
• Shelley, D. (1993). Igneous and metamorphic rocks under the microscope: classification, textures, microstructures and mineral preferred-orientations.
• Vernon, R. H. & Clarke, G. L. (2008): Principles of Metamorphic Petrology. Cambridge University Press.

Photo
Plagioclase crystals in a adcumulate. XPL image. 2x (Field of view = 7mm)	Plagioclase crystals in a adcumulate. XPL image. 2x (Field of view = 7mm)	Plagioclase and Orthopyroxene crystals in a adcumulate. XPL image. 2x (Field of view = 7mm)
Plagioclase and Orthopyroxene crystals in a adcumulate. XPL image. 2x (Field of view = 7mm)	Plagioclase crystals in a adcumulate. XPL image. 2x (Field of view = 7mm)	Plagioclase and Orthopyroxene crystals in a adcumulate. XPL image. 2x (Field of view = 7mm)
Plagioclase crystals in a adcumulate. XPL image. 2x (Field of view = 7mm)	Plagioclase and Orthopyroxene crystals in a adcumulate. XPL image. 2x (Field of view = 7mm)	Plagioclase crystals in a adcumulate. XPL image. 2x (Field of view = 7mm)