Geochemical and isotopic characteristics of Zangalline marble, Ranya area, Qandil Series, northeastern Iraqi Kurdistan Region: implications for genesis

Abstract

The Zangalline marble of Paleogene age outcrops in Qandil Thrust Blocks, which are situated in NE Iraq close to the Iranian borders about (16) km from Haj Umaran town, NE Iraq within the thrust front and elevation ranging between (600–1568) m. The marble has been quarried for a long time and has been used as building stone and dimension stone. Chemical characteristics of these marbles are used to determine their provenance. The samples were subjected to a series of analytical techniques, including X-ray fluorescence and C-O isotope analysis. The Zangalline marbles have variable content of Si and Al from almost silicate rich rocks to pure marble and may have been deposited in shallow structural basins. The Chemical Index of Alteration and the Chemical Index of Weathering have the same percentage range values of 12.32–72.74% and 12.33–73.78% with an average value of 27.80 and 27.99 indicating that a low degree of weathering of the source materials must have taken place. The relatively high contents of K2O and Na2O suggest that the source rocks may have been exposed to very week physical and chemical weathering. The tectonic discrimination diagram suggests that the marble of Zangalline area is quartz-rich sediments and derived from plate interiors or stable continental areas and deposited in passive continental margins. The average carbon and oxygen isotope ratios of Zangalline marbles are 2.289% and 25.16%, respectively indicated that the deposit was a typical marine carbonate source and belong to similar geological units which the source may be Aqra Bakhma, Qamchuuqa Formations and/or Sarmord Formations, recrystallized at low temperatures in the open system coupled with either CO2 out gassing or fluid/rock interactions and the heat energy was most likely derived from nearby magmatic fluid/rocks.