Coesite in the Straumen kyanite-eclogite pod, Norway

The occurrence of coesite in the Straumen kyanite-eclogite pod in the Western Gneiss Region (WGR), Norway, is described. Although the microtextures of coesite, and of its partial or complete transformation into quartz, are similar to those described at the first coesite occurrence in Norway (the Grytting dolomite-eclogite pod) there are some significant differences at this second locality. These include the host mineral of the SiO2 inclusions being garnet, instead of clinopyroxene, and also occasionally kyanite. An initial coesite-eclogite (sub) facies paragenesis was followed by a quartz-eclogite (sub) facies paragenesis which, in addition to rutile and dolomite or calcite, contains the highest number (7) of silicate phases known in any Norwegian eclogite: garnet, clinopyroxene, kyanite, quartz, phengite, zoisite and clinoamphibole. This second occurrence of definite coesite: (i) consolidates the very high pressury estimates (about 30 kbar minimum) previously deduced for certain eclogite pods occurring in the WGR; and (ii) justifies the recognition of the 'Norwegian coesite-eclogite province' constituted of a nappe (terrane) of about 30 kbar parageneses now residing in the WGR.