Peraluminous rock - Wikipedia
Peraluminous rocks are igneous rocks that have a molecular proportion of aluminium oxide higher than the combination of sodium oxide, potassium oxide and calcium oxide. [1] This contrasts with peralkaline in which the alkalis are higher, metaluminous where aluminium oxide concentration is lower than the combination, but above the alkalis, and ...
Peraluminous I-type granites - ScienceDirect
2012年11月15日 · Almost half (49.3%) of the I-type granites for which bulk chemical compositions are available are peraluminous — those peraluminous granites are known to be I-type because of their close association in space and character with less felsic metaluminous I-type granites.
The Origins of Strongly Peraluminous Granitoid Rocks
Strongly peraluminous granites (SPAGs), with 1.20 < A/CNK < 1.30, are relatively rare rocks. They contain significant modal abundances of AFM minerals such as Bt-Ms-Crd-Grt-And-Toz-Tur-Spl-Crn of potentially magmatic, peritectic, restitic, and xenocrystic origin.
General Classification of Igneous Rocks - Tulane University
If there is an excess of Alumina over that required to form feldspars, we say that the rock is peraluminous. This condition is expressed chemically on a molecular basis as: Al 2 O 3 > (CaO + Na 2 O + K 2 O)
Strongly Peraluminous Granites across the Archean–Proterozoic ...
2019年6月7日 · Peraluminous granites are those that include corundum in their CIPW norms (Shand, 1927). This translates into excess Al 2 O 3 in their bulk composition that cannot be accommodated in feldspar by coordinating with Ca, Na, and K.
Structure, geochronology, and petrogenesis of Permian peraluminous …
2022年9月1日 · INTRODUCTION. Peraluminous granites, whose distinguishing feature is high alumina saturation index (ASI = molar Al 2 O 3 / (CaO + Na 2 O + K 2 O) > 1.0), widely occur within orogenic belts worldwide and provide essential clues for crustal rheological and thermal evolution (Sylvester, 1998).
Genesis of the two main types of peraluminous granitoids
1996年4月1日 · Two-mica monzogranites to leucogranites and biotite-rich, cordierite-bearing tonalites to monzogranites form two distinct groups of peraluminous granitoids. They can be distinguished by mineral and rock associations and by the …
Peraluminous granitoid rocks are defined chemi-cally as those in which the ratio (molecular pro-portions) ALOg/ (CaO + NarO + KnO) (= A/ CNK) > l. Mineralogically these sranites consist of quartz * two feldspars { one or more character-istic phases such as biotite, muscovite, garnet, cor-
A Geochemical Classification for Granitic Rocks - Oxford Academic
2001年11月1日 · Those with <70 wt % SiO 2 are dominantly metaluminous, whereas more silica-rich varieties are commonly peraluminous. Peraluminous leucogranites may be either magnesian or ferroan and have a MALI that ranges from calcic to alkalic.
A re-examination of the typology of peraluminous granite types …
2011年11月3日 · Moreover, peraluminous granite types have not been clearly discriminated in recent revisions. The study of several peraluminous series in different intracontinental orogenic belts reveals that four distinct groups can be defined.