Mineralogy of Kurtulmuş iron deposit-an example to the skarn-type ore deposits from eastern pondites (Giresun-NE Turkey)
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2003
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Abstract
Giresun'un yaklaşık 30 km güneyinde bulunan Kurtulmuş demir yatağı,kalk silikat, demir skarn olarak kabul edilmiş olup, Jura-Alt Kretase yaşlı kirectaşları ve mafik volkanik kayaçların, sokulum yapan Paleosen yaşlı asidik kor kayaçlarla kontağı boyunca, pirometazomatik olarak yataklanmıştır. Kirectaşları ve mafik kayaçların her ikisi de esas olarak granodiyorit bileşimindeki sokulum yapan intrüsif kayaçlarca metamorfizmaya uğratılmışlardır. Maden yatağı %45 F e tenörlü yaklaşık 500 bin tonluk kesin rezerve sahiptir. Ana cevher mineralleri pirotin ve magnetit olup, değişen miktarlarda pirit ve kalkopirit ile eser miktarda sfalerit bulunur. Sfalerit varlığı kusma kütleleri şeklinde sıkı sıkıya kalkopirit ve daha az oranda pirotin ile ilişkilidir. İkincil cevher mineralleri kovelit, hematit, limonit, lepidokrosit, götit ve ara Fe-oksit hidroksitlerden oluşmaktadır. İkinci bir pirit jenerasyonu da,pirotinin bozuşmasının bir sonucu olarak metastabil markazit ile beraber-büyüme gösterir. Gang mineraller esas olarak kalsit ve kuvarstan oluşur. Birincil cevher beraber-büyüme dokuları genel olarak eş daneli ve porfiritik cevher dokularıdır. İkincil cevher dokuları, ayrışmanın yoğun olduğu yerlerde yerel olarak önem arzeder ki bunlar kuş gözü, konsantrik, sferoyidal ve koloform büyüme dokularıdır.
The Kurtulmuş iron deposit, located about 30 km south of Giresun (NE Turkey), is considered to be a calc-silicate Fe-skarn that is pyrometasomatically deposited along the contact zone of limestones and mafic volcanic rocks of Jurassic-lower Cretaceous age intruded by acidic igneous rocks of Paleocene age. The limestones and the mafic rocks are both metamorphosed by the intrusives, which are mainly granodiorite in composition. The ore deposit has a definite reserve of about 500 thousands tons with an average 45 wt % Fe content. Major primary ore minerals include pyrrhotite and magnetite along with varying amount ofpyrite and chalcopyrite, accompanied by trace sphalerite. Presence of sphalerite is strictly associated with the chalcopyrite and to a lesser extent with pyrrhotite as exsolved bodies. Secondary ore minerals include covellite, hematite, limonite, lepidocrocite, goethite, and intermediate Fe-oxides-hydroxides. A second generation of pyrite intergrown with metastable marcasite is also present as a result of pyrrhotite weathering. Gangue minerals are mainly calcite and quartz. Primary intergrowth ore textures are mainly equigranular and porphyritic ore textures. Secondary ore textures locally become significant where weathering is intense, which include bird's eye, concentric, spheroidal, and colloform microtextures.
The Kurtulmuş iron deposit, located about 30 km south of Giresun (NE Turkey), is considered to be a calc-silicate Fe-skarn that is pyrometasomatically deposited along the contact zone of limestones and mafic volcanic rocks of Jurassic-lower Cretaceous age intruded by acidic igneous rocks of Paleocene age. The limestones and the mafic rocks are both metamorphosed by the intrusives, which are mainly granodiorite in composition. The ore deposit has a definite reserve of about 500 thousands tons with an average 45 wt % Fe content. Major primary ore minerals include pyrrhotite and magnetite along with varying amount ofpyrite and chalcopyrite, accompanied by trace sphalerite. Presence of sphalerite is strictly associated with the chalcopyrite and to a lesser extent with pyrrhotite as exsolved bodies. Secondary ore minerals include covellite, hematite, limonite, lepidocrocite, goethite, and intermediate Fe-oxides-hydroxides. A second generation of pyrite intergrown with metastable marcasite is also present as a result of pyrrhotite weathering. Gangue minerals are mainly calcite and quartz. Primary intergrowth ore textures are mainly equigranular and porphyritic ore textures. Secondary ore textures locally become significant where weathering is intense, which include bird's eye, concentric, spheroidal, and colloform microtextures.
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Yerbilimleri, Ortak Disiplinler
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Geosound
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43
