The magnetite-apatite ore deposits of Turkey occure along the Southeast Anatolian Trust Belt of Turkey. There are three structural zones, Pütürge Massif and Malatya Metaphorites in the west, Bitlis Massif in the east, which have gained their present position by transportations during thrusts developed in the Miocene tectonics of Southeastern Anatolia. These in greenschist facies of a regional metamorphism metamorphised and formed deposits are Avnik and Ünaldı in Bitlis Massif and Pınarbaşı Malatya Metaphorites. The most common property of the ores deposits is that the ores depend on greenschists and found as lenses of massive, banded and dissiminited of martitized magnetite and fluorapatite.
In the area of the Pınarbaşi deposit listed here as an example crop out the Precambrian (Pütürge Metamorphites), the Eocene (Maden Complex), the Permo-Carboniferous (Malatya Metamorphites), the Tertiary, the Quaternary conglomerates and the alluvial formations. The Malatya Metamorphites are in an area thrust over the Maden Complex. From bottom to top, the area includes chlorite schists, calc schists and recrystallized limestone. Abundant rock-forming minerals in the area include chlorite, mica, quartz and calcite. The existing mineral facies indicate that ore deposits in the area metamorphosed as at least one regional barrow type in the green schist facies under 400°C temperature and 0.4 MPa pressure, and they depend on contact and retrograde metamorphism. As a result of this process, the area’s ore deposits are highly folded and faulted. The ores consist of magnetite, hematite (specularite) and goethite. The important gangue minerals are fluorapatite, quartz, chlorite and micas. Rarely observed allanite, monazite, xenotime and zirconia. Geologic and geochemistry data indicate that educts of the recent metamorphosed rocks’ chlorite schist were pelitic sediments.
The trace and rar earth elements analysis indicat that a harmonious relation determined between Fe and P2O5 in all ore deposits. The most enriched elenents in relation to Clarke values are P (8-17 times), Fe (5-10 times) and V (3-6 times). The rocks, ores and minerals of the deposit are relatively poor in trace and rare earth elements. Magnetites contain approximately 900 ppm V, 300-700 ppm Mn, 60-180 ppm Cr and 40-150 ppm Ni.The total concentration of rare earths varies between 200-500 ppm. However, rare earth elements concentration of apatites varies between 3000-4000 ppm. Their normalized distributions according to chondrites are characterized by good separation and a marked Eu negative anomaly.
Levels of the 18O isotope showed that the formation temperature varied between 282-372 ºC. This temperature corresponds to the beginning of the green schist facies temperature of the regional metamorphism. Hydrogen isotope analysis reflects the sedimentary rock’s value and supports the geochemistry diagnosis. The radiometric age determination indicated two different age values, 66 and 48 Ma. The older age of 66 Ma explains the metamorphosis that evolved during the ophiolite development. The younger age of 48 Ma is interpreted as a second metamorphism, retrograde metamorphism or tectonic movement age.
Pınarbaşı deposit is defined as a Kiruna type sedimentary deposit. Total reserves amount to 66 Mt with 35.07wt % Fe and 1.57wt % P2O5 content. The operation of the ore is currently in planning.
Prof. Dr.-Ing., Hüseyin Çelebi
Mersin University, Department of Geology, 33343 Mersin, Turkey.