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Aluminous granulites from the Pulur complex, NE Turkey : a case of partial melting, efficient melt extraction and crystallisation
Auteur(s)
Topuz, Gültekin
Altherr, Rainer
Satır, Muharrem
Werner, Olaf
Schwarz, Winfried H.
Date de parution
2004
In
Lithos, Elsevier, 2004/72/3-4/183-207
Résumé
In the Pulur complex, NE Turkey, a heterogeneous rock sequence ranging from quartz-rich mesocratic gneisses to silica- and alkali-deficient, Fe-, Mg- and Al-rich melanocratic rocks is characterized by granulite-facies assemblages involving garnet, cordierite, sillimanite, ilmenite, ±spinel, ±plagioclase, ±quartz, ±biotite, ±corundum, rutile and monazite. Textural evidence for partial melting in the aluminous granulites, particularly leucosomes, is largely absent or strongly obliterated by a late-stage hydrothermal overprint. However, inclusion relations, high peak <i>P–T</i> conditions, the refractory modes, bulk and biotite compositions of the melanocratic rocks strongly support a model of partial melting. The melt was almost completely removed from the melanocratic rocks and crystallised within the adjacent mesocratic gneisses which are silica-rich, bear evidence of former feldspar and show a large range in major element concentrations as well as a negative correlation of most elements with SiO<sub>2</sub>. Peak conditions are estimated to be ≥800 °C and 0.7–0.8 GPa. Subsequent near-isothermal decompression to ~0.4–0.5 GPa at 800–730 °C is suggested by the formation of cordierite coronas and cordierite–spinel symplectites around garnet and in the matrix. Sm–Nd, Rb–Sr and <sub>40</sub>Ar/<sub>39</sub>Ar isotope data indicate peak conditions at ~330 Ma and cooling below 300 °C at ~310 Ma.
Identifiants
Type de publication
journal article
