engleski

Occurrence of clinozoisite-epidote minerals in the metamorphic suite and granitic intrusions of the Dunje area, South Macedonia

Epidote group minerals occur in various geological settings reflecting local lithology and geological history. From petrogenetic point of view these minerals are quite unspecific because of wide temperature and pressure stability fields (Franz & Liebscher, 2004). The Dunje area is situated in the Pelagonian Massif of southern Macedonia comprising a Precambrian metamorphic suite composed of gneisses, amphibolites and schists. Granitic intrusions and concomitant pegmatitic veins in the metamorphic host rocks are quite common (Temovski, 2016). The studied area is located 3 km in SSW direction from village of Dunje. Occurrence of the clinozoisite-epidote series minerals in the granitic intrusions and host gneisses in contact with pegmatite veins is investigated in this study. The studied granitic rocks outcrop roughly 100 m in NNE direction from the investigated gneiss-pegmatite contact. Plane-polarized light microscopy (Zeiss, Axiolab) and scanning electron microscopy (SEM) with EDS system (Bruker, Quantax 70) were used to study micro-features of the rock samples with special interest into the co-existence of clinozoisite-epidote minerals and Ti-rich phases, which both seem to be quite abundant in the investigated rock suite. The host gneiss is coarsely foliated and composed of clinozoisite-epidote, amphibole, quartz, plagioclase, titanite and sparse but large grains of opaque minerals. The intruding granite is composed of quartz, orthoclase with occasional perthitic lamellae, biotite, small elongated or irregular grains of clinozoisite-epidote, 533 titanite, and sparse garnet. The occurrence of clinozoisite and epidote in both host gneiss and granite represents a mineral chemistry change at small scale, and even in polarizing light epidote and clinozoisite are readily distinguished by a clear distinction in interference color. Both minerals appear mutually in a very close contact (Figure 1A and 1B ; Ep – epidote, Czo – clinozoisite, Amp – amphibole, Ttn – titanite, Pl – plagioclase). SEM-EDS analysis (Figure 1C and 1D) indicates an inhomogeneous distribution of iron throughout the clinozoisite-epidote grains, thus giving rise to a simultaneous occurrence of both phases. Amphibole is of Mg-Fe series containing some Ca (intergrowths?), and a frequent occurrence of titanite indicates a significant availability of titanium in both metamorphic suite and granite. Besides, in the host gneiss rutile grains are also identified. A detailed micro-chemical characterization of the mineral phases in the rocks of the studied metamorphic suite is in progress especially focusing to a possible relationship between occurrence of clinozoisite-epidote minerals in host rocks and granitic/pegmatitic intrusions.

clinozoisite-epidote mineral series, metamorphic suite South Macedonia, polarizing light microscopy, SEM-EDS

nije evidentirano