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A re-examination of the typology of peraluminous granite types in intracontinental orogenic belts

Villaseca González, Carlos and Barbero González, Luis C. and Herreros Villanueva, Víctor Manuel (1998) A re-examination of the typology of peraluminous granite types in intracontinental orogenic belts. Transactions of the Royal Society of Edinburgh. Earth sciences , 89 . pp. 113-119. ISSN 0263-5933

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Abstract

Conventional rock c1assifieation diagrams do not distinguish the variety of peraluminous
rock series. Moreover, peraluminous granite types have not becn clearly discriminated in
recent revisions. The study of several peraluminous series in different intraeontinental orogenie belts
reveals thal four distinct groups can be defined. Using an A- S diagram, these fout groups are:
(1) highly peraluminous granitoids (hP) characterised by high A values and typified by an increase
in peraluminosity toward the most mafic varieties; (2) moderately peraluminous granitoids (mP)
which occupy the intermediate field and generally show increasing peraluminosity towards the most
mafic varieties; (3) low peraluminous granitoids (IP) which plot in the lowest parl of the peraluminous
field defin ing negative slope trends; (4) highly felsic peraluminous granites U P) with poorly defined
variation trends.
In intracontinental orogenic belts, the genesis of peraluminous granitie series is favoured by the
abundante of fertile crustal protoliths, mainly metapelites, metaigneous rocks and metagreywackes.
The difficulty of attaining temperatures in excess of 950°C al lower crustal levels during the
tectonothermal evolution of thickened crust, inhibits the partial metting of more basic sources.
Although the physical parameters of the melting process influence their chemical and mineralogical
characteristics, source rock composition ultimately determines the degree of peraluminosity of the
granitic series.

Item Type:Article
Uncontrolled Keywords:Collisional orogenic magmatism, Crustal protoliths, Granite classification
Subjects:Sciences > Geology > Petrology
ID Code:12319
Deposited On:01 Mar 2011 10:34
Last Modified:29 Aug 2011 07:37

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