Apatite-rich iron deposits of the Avnik (Bingoel) region, southeastern Turkey

Mineral.-Geol. Mus., Oslo, Norway

Apatite-rich iron deposits are interbedded with gneisses and intermediate to felsic calc-alkaline metavolcanics (450 m.y. old) which show some well-preserved porphyritic, spherulitic, and volcaniclastic textures. They are intruded by the heterogeneous Avnik granitoid and the homogeneous Yayla granite (350 m.y. old). Iron ores are banded, massive, or disseminated and are located in a gradational zone between the gneisses and better preserved parts of the metavolcanic rocks. Magnetite, fluorapatite, and actinolite are dominant minerals in the three types of deposits; accessory minerals are feldspar, quartz, mica, diopside, hornblende, crossite, and sphene. Evidence suggests that the apatite-rich iron deposits formed initially during volcanism, and it is concluded that they were immiscible liquids which had separated from strongly fractionated magmas. Similar rare earth element values in coexisting apatite and magnetite and in the associated metavolcanic rocks support this conclusion. The apatite-rich iron deposits were remobilized into stockworks containing large crystals of magnetite, apatite, and actinolite where these have been intruded by the Avnik granitoid.--Modified journal abstract.

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