felsic

comparative more felsic · superlative most felsic

1. geographyEnriched in minerals predominantly composed of the lighter elements such as silicon, oxygen, aluminium, sodium, and potassium.

   Much of the southern half of the southeastern body is a mafic syenite, slightly more felsic than the shonkinite.

   1954, J. C. Olson, D. R. Shawe, L. C. Pray, W. N. Sharp, Rare-Earth Mineral Deposits of the Mountain Pass District, San Bernadino County, California, U.S. Geological Survey, Professional Paper 261, page 22

   2 more examples

   Within comagmatic suites, successively younger granitoids are commonly, but not invariably, more felsic, representing progressively lower temperature mineral assemblages.

   1983, Paul C. Bateman, “A summary of critical relations in the central part of Sierra Nevada batholith, California, U.S.A.”, in J. A. Roddick, editor, Circum-Pacific Plutonic Terranes, Geological Society of America, Memoir 159, page 241

   The Claret Creek Supersuite granites are a little more felsic (65-77% SiO₂), and are chemically distinctive, having higher Al₂O₃, CaO, Na₂O and Sr, and lower K₂O, Rb, Th and U than the granites of the Almaden Supersuite.

   1992, David C. Champion, Bruce W. Chappell, “Petrogenesis of felsic I-type granites: an example from northern Queensland”, in P. E. Brown, B. W. Chappell, editor, The Second Hutton Symposium on the Origin of Granites and Related Rocks, Geological Society of America, Special Paper 272, page 115

   Synonyms: acidic, sialic, silicic

plural felsics

1. A rock with such properties.

   There are also calcalkaline felsics that have highly enriched LREE^([light rare-earth element]) patterns with lower overall abundances.

   1992, T. E. Smith, chapter 1, in K. C. Condie, editor, Proterozoic Crustal Evolution, Elsevier, page 35

   1 more example

   The central part of this nepheline syenite is very white felsics with black mafics in it. The entire area contains many nepheline-bearing dike rocks, but almost all are gray or pink or even red due to the color in the felsics.

   1953, R. C. Emmons, “Petrogeny of the Syenites and Nepheline Syenites of Central Wisconsin”, in R. C. Emmons, editor, Selected Petrogenic Relationships of Plagioclase, Geological Society of America, Memoir 52, page 80