ABSTRACT

Sidakan-Balakyan River (SBR) is located near the Iranian border northeastern part of the Iraqi Kurdistan Region. This study deals with both water and stream sediment of the SBR as regards hydrochemistry and geochemistry. Hydrochemical research focuses on analyzing water’s physical and chemical characteristics and controlling factors in evaluating the water quality of the SBR. The geochemistry of recent sediments was analyzed for their major, trace, and rare earth elements to identify the provenance, tectonics, and paleo-weathering. 

The thirty-two water samples were collected along the Sidakan-Balakyan River to the junction point of the Sidakan-Rwanduz Rivers for both periods; for each sample, physical (pH, EC, T ̊C, Turb., TDS, TH) and chemical parameters (Mg²⁺, Ca²⁺, K⁺, Na⁺, HCO₃^–, Cl^–, SO₄^2-, NO₃^–) were analyzed. The results showed that all water samples were within the acceptable range according to WHO (2008) and IQS (2009) guidelines, except the turbidity, which is very high.  The results obtained from the Piper and Chadha diagram indicate that the studied water samples during the High Flow Period (HFP), all are Mg²⁺– Bicarbonate as well as Ca²⁺ and SO₄^2-, whereas during the Low Flow Period (LFP) in Sidakan river is Mg²⁺– Bicarbonate, while in Balakyan and Rwanduz Rivers are Ca²⁺– Bicarbonate. Moreover, based on Gibbs Diagram, water samples were distributed in the rock-water weathering dominance section. Additionally, based on TDS and TH, water samples were found to be moderately to hard fresh water. Most samples have a WQI between Good to Excellent, except for some samples where the Water Quality Index (WQI) is unsuitable during the High Flow Period (HFP).

Twenty-five stream sediment samples were analyzed geochemically. The sediments are classified as Fe-shale and Fe-sand. Revealed by the ICV values of SBR sediments are immature. Several bivariate plots, such as Al₂O₃/TiO₂ versus SiO_{2 adj}, and Rb vs K₂O, and enrichment in the transition elements (Ni, Cr, Zn, Co, Cu, and Sc), low ratio of LREE/HREE, ternary V-Ni-Th*10 diagrams, elemental ratios (Al₂O₃/TiO₂, Th/Sc, and La/Th), REE pattern and size of Eu, reveal that the SBR sediments are derived from the source area dominantly composed of mafic rocks with intermediate. The CIA, PIA and CIW values and A-CN-K plots indicate that the source areas underwent a low to moderate chemical weathering intensity. Tectonic discrimination diagrams (K₂O/Na₂O vs SiO₂, SiO₂/Al₂O₃ vs K₂O/Na₂O, La-Th-Sc and Th-Sc-Zr/10 plot) suggested that SBR sediments were derived from oceanic island arc with active continental margin. The tectonic discrimination of siliciclastic sediments in the samples plotted between arc, rift and collision settings suggest that SBR sediments were derived from both active and passive continental margins. The active tectonic settings match the northeastern uplands along the Arabian and Iranian Plates subduction zones.