Geochemistry of major, Trace and rare earth elements in to the Aqra Carbonate rocks taken from Geli Zanta section/ Northern Iraq

Abstract

A total of 13 carbonate rocks samples represented Aqra Formations deposited in the reefal environment, Chemical results of Aqra samples showed that the formation could be divided into two parts, lower part is limestone while the upper part has been subjected to dolomitization prosses, the two parts are separated by a transitional strata which have been less dolomitized. Its noticed that the upper part contain higher concentrations of trace elements like Cr, Ni, Co, Sc, the concentrations of this elements (9.33, 9.47, 3.15, 0.95)ppm in lower part and (57.25, 75.88, 5.68, 2.13)ppm in upper part respectively, which indicated that this part has been subjected to the influences of mafic and ultramafic provenance in contrast to the lower part, The rare earth elements (REE) content was also different in the two parts, there is relatively depletion in the light rare earth elements (LREE) towards the upper part (4.56ppm – 4.07ppm) with increase in the insoluble residue (I.R.) content from 2.84% to 5.60% and increase in the heavy rare earth elements (HREE) towards to upper part (0.52ppm – 0.78ppm), The ƩREE is 5.08ppm in lower part and 4.85ppm in upper part, This is also reflection of the difference in the nature of the terrigeneous component which the two parts where supplied. Negative Ce anomaly was noticed in the parts which are not dolomitized of the Formation involved in the present study but absent in the dolomitized part. Through the study of binary relations between major and trace elements its shown that the major part of trace are well correlated with the terrigeneous constituents and not correlated with the carbonate phases, The sedimentation basin which Aqra deposited was affected by the tectonic activities happened at that time, this is supported by the presence of trace elements of mafic nature associated with the terrigeneous clasts which the basin of deposition received.

Keywords

• geochemistry
• rare earth elements
• aqra formation
• geli zanta
• northern iraq