Structural and petrological features of peridotite intrusions from the Troodos Ophiolite, Cyprus

Abstract

Strings of intrusive peridotite cut through the layered ultramafic cumulates and gabbroic rocks of the Troodos plutonic core. The massive and undeformed peridotite has a typical poikilitic texture with olivine (Fo 84-90) and spinel grains (Cr* 59-68) enclosed by oikocrysts of magnesian augite (En51 Wo43 Fs6), orthopyroxene (En 83-87) and calcic plagioclase (An 92-93). Late interstitial pargasitic hornblende is locally abundant. Bulk chemistry and mineralogy of the poikilitic peridotite are close to those of undepleted mantle lherzolite suggesting that the intrusive rock is the product of extensive melting of a fertile mantle source. The parental magma consisted of a mixture of basaltic melt and mantle residual solid phases such as olivine and spinel. It is postulated that such a magmatic mixture can only be collected in mantle diapirs reaching the base of ophiolite crusts. -Authors