peralkaline

peralkaline

[pər′al·kə‚līn]
(petrology)
Of igneous rock, having a molecular proportion of aluminum lower than that of sodium oxide and potassium oxide combined.
McGraw-Hill Dictionary of Scientific & Technical Terms, 6E, Copyright © 2003 by The McGraw-Hill Companies, Inc.
References in periodicals archive ?
and Morris, C.: 2016, Geology and genesis of the Toongi rare metal (Zr, Hf, Nb, Ta, Y and REE) deposit, NSW, Australia, and implications for rare metal mineralization in peralkaline igneous rocks.
Igneous processes such as partial melting, crustal assimilation, melt immiscibility, and fractional crystallization, along with crustal metasomatism, can lead to the formation of REE-enriched carbonatite, alkaline, and peralkaline melts [2, 10-15].
1): Bocabec Gabbro--greyish green, locally layered, medium-grained gabbro and minor associated granitic rocks; Utopia Granite--typically red, leucocratic, medium--to coarse-grained, equigranular, biotite granite; Welsford, Jake Lee Mountain, and Parks Brook granites--beige to pink, mediumgrained and equigranular to fine-grained and porphyritic, amphibole-bearing, peralkaline granites; Magaguadavic Granite--greyish pink, coarse-grained, megacrystic granite; John Lee Brook Granite--light grey, medium-grained, equigranular, garnetiferous, two-mica granite; and Mount Douglas Granite--light pink, medium-to-coarse-grained and equigranular to fine-grained and porphyritic, rapakivitextured, biotite granite.
They also provide a good explanation of where REEs tend to be located, from iron and carbonatite deposits to lateritic, placer, peralkaline, vein, and other deposits.
Based on published data, Jan and Karim (1990) suggested that the alkaline and peralkaline magmatism in the Peshawar plain is related with Permian-Triassic rifting of the Gondwana.
Two main lineages are apparent for the potassic rock-types (Figure 5 and inset (II)): (1) a silica undersatured lineage (B-P) ranging from basanite to phonolite and peralkaline phonolite and (2) a silica-saturated lineage (AB-T) ranging from alkali basalt to trachyphonolite and trachyte [13,42,44].
Metaluminous rhyolite obsidian (type S1) from Sacanana (42[degrees]30'S; 68[degrees]36 W) and peralkaline rhyolite obsidian (type T/SC1) from Sierra Negra (42[degrees]18'S; 66[degrees]36'W) have been described for this area (Mendez et al.