عنوان مقاله [English]
Dopolan bauxite deposit is located in the high Zagros zone, between Khaneh-Kat and Neyriz Formations. Dopolan bauxite consist of 5 separate layer bauxite, respectively from bottom to top including, iron rich, clay bearing, oolitic, pisolitic and organic matter-rich bauxite. The aim of this study is investigation on the role of organic matter in the mineralogy deposition of bauxite horizons. Mineralogical studies inclusive light microscopy (reflected), electron microscopic (SEM) and Raman spectroscopy, revealed presence of diaspore in pisolitic, oolitic, clay bauxitic horizons and show presence of pyrite, kaolinite, nacrit, bohemite, minerals in organic matter rich and iron rich bauxitic horizons. The micromorphelogical studies show that deferruginization is important process in the deposit. Iron rich and organic rich bauxite horizons show highest values TOC and Fe. The most specific feature of iron-rich and organic matter-rich bauxitic horizons is abundant of pyrite. Present pyrite was explained by high content of organic carbon. The widespread occurrences of pyrite in these horizons seem to be due to the sulfate reduction by bacteria in relatively organic carbon-rich environment. Distribution of organic matter show that carbon control mobilization of Fe and Al during bauxitization. Therefore two environmental condition can be deduced in Dopolan deposit. 1) Environment that Al minerals more soluble than Fe minerals 2) Environment that Fe minerals more soluble than Al minerals.