Effects of Metamorphism in the Guleman ophiolite

Authors : Yusuf Ziya Özkan

Pages : 1-11

View : 18 | Download : 8

Publication Date : 1984-06-01

Article Type : Research

Abstract : 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.
Keywords : troktolit, olivin, gabro, rodenjitleşme, troctolite, olivine gabbro, rodengitised up