Effects of Metamorphism in the Guleman ophiolite

Yıl 1984, Cilt: 101-102 Sayı: 101-102, 1 - 11, 01.06.1984

Yusuf Ziya Özkan

Öz

 Investigations carried on the Guleman ophiolite show that mineral assemblages were subject to transformations
as a result of penetrative H2O and CO2 at temperatures relatively lower than that of their formation. The following
parageneses were generated as a result of these transformations. In ultramafic rocks: Lizardite/chrysotile +
magnetite + chlorite + diopside, lizardite/chrysotile + talc + magnetite + magnesite + chlorite, magnesite +
silica + serpentine + hematite; in mafic rocks: lizardite + hybschite + magnetite + chlorite (in trochtolites), serpentine
+ chlorite + actinolite + epidote + prehnite + sericite + magnetite + chybschite + albite (in olivine-gabbros),
actinolite + chlorite + epidote + prehnite + sericite + magnetite (in ordinary gabbros), chlorite + sericite + magnetite
(in quartz-gabbros/diorites), actinolite + chlorite + epidote + prehnite + sericite ± serpentine (in gabbroic dykes),
chlorite + actinolite + epidote + albite + prehnite + sericite + quartz + calcite (in diabase dykes), hybschite +
chlorite + diopside + magnetite (in rodengitised basic dykes). It was concluded, with consideration of experimental
data of the relevant systems, that these parageneses were formed under relatively low pressures and temperatures not
reaching that of greenschist facies. On the other hand, in the light of plate tectonics hyphothesis and with special consideration
of the serpentinization pattern, it is defended that these transformations were principally realised during
emplacement of ophiolites in Upper Cretaceous or re-transportation in Miocene. In addition, it seems highly probable
that the transformations, with augmentation of intensity in the vicinities of cumulate-tectonite contacts, were realised
through autohydrothermal effects of cumulate forming magmas.

Anahtar Kelimeler

troktolit, olivin, gabro, rodenjitleşme, troctolite, olivine gabbro, rodengitised up

Teşekkür

The author is indebted to Dr. Ahmet Çağatay for his kind help in determinations of opaque minerals and to Nuran Güngör for preparation of X-ray diffraction graphs. Expert guidance of Dr. Evren Yazgan in optical determinations of silicate minerals and Dr. Tandoğan Engin's kind suggestions and critical review of the manuscript must gratefully be acknowledged.

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