Geochemical Implications for Tectonic Setting of the Ophiolitic Rocks From the Ophiolitic Melange Belt of the Ankara Melange

Yıl 1990, Cilt: 110 Sayı: 110, 17 - 28, 01.03.1990

Ayla Tankut

Öz

Ophiolite melange of Cretaceous age is the youngest belt of the Ankara melange and consists mainly of ophiolitic
rock fragments such as serpentinite, gabbro, dolerite and basalt of varying sizes, together with pelagic radiolarites and limestones.
The ophiolitic melange includes also large isolated masses which are considered to be preserved slices of oceanic lithosphere. The
mafic clasts in the melange and the basic dyke rocks of an oceanic lithosphere fragment, Edige body, have comparable compositions.
The petrographic and geochemical characteristics of the ultrabasic rocks of the ophiolite melange are correlated with those
of depleted mantle peridotite whereas trace element contents, particularly REE, of the basic rocks are within the range of abyssal
tholeiites. These ophiolites are believed to be representative of suboceanic environment. However the basic rocks, with their higher
LIL and lower HFS element contents relative to MORB, demonstrate island arc characteristics. Such features imply a marginal
basin tectonic setting rather than a major ocean basin for the ophiolitic rocks of the melange. The magmas of the basic rocks have
most probably been generated by back arc spreading and have been modified by subduction related fluids later. 

Anahtar Kelimeler

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Kaynakça

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