Original paper

Origin of S-type granites coeval with I-type granites in the Hellenic subduction system, Miocene of Naxos, Greece

Pe-Piper, Georgia

European Journal of Mineralogy Volume 12 Number 4 (2000), p. 859 - 875

31 references

published: Jul 17, 2000
manuscript accepted: Feb 29, 2000
manuscript received: Sep 12, 1998

DOI: 10.1127/ejm/12/4/0859

BibTeX file

ArtNo. ESP147051204013, Price: 29.00 €

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Abstract

Abstract The island of Naxos in the Cyclades preserves a core complex developed by Miocene detachment faulting associated with extension of continental crust inboard of the Hellenic subduction zone. The extension has unroofed Miocene hornblende-biotite granite and leucogranite, previously defmed as I-type and S-type granite respectively. Crystalline basement exposed by extension includes partially migmatised ortho- and paragneisses principally with Hercynian protolith ages and intercalated high-grade metasedimentary and metavolcanic rocks with Mesozoic protoliths. Most leucogranites, in addition to quartz, feldspar and biotite contain muscovite, tourmaline and garnet (almandine-spessartine). Mineral assemblages suggest crystallisation pressures < 2.5 kbar, with stability of muscovite and tourmaline resulting from high B, Mn and possibly F in the magma. Two types of leucogranite can be distinguished on the basis of rock chemistry, mineral chemistry and NdiSm isotopes. Earlier leucogranites (type II) have high LREE:HREE ratio, high LILE, low Y and Nb and ɛNd ~-10 and appear to be a partial melting product of Hercynian paragneiss. Leucogranite dykes within the I-type granite appear similar. Later leucogranites (types Ia, Ib) have low LREE:HREE ratio and ɛNd ~-7 and appear to be derived from melting of both Hercynian paragneisses and younger metasediments. The major element composition of rare leucogranite type Ie suggests derivation from partial melting of orthogneiss. These varied sources result in significant variation in mineral assemblages in the leucogranites

Keywords

GreeceCycladesleucogranitetourmalinegarnetNd isotopesI-type graniteS-type granite