SUBSURFACE GEOLOGICAL STUDY OF SOUTH AL-NASIRIYA REGION SOUTH IRAQ

Abstract

Generally, the study area is located in northeast of the Southern Desert, between Al-Nasiriya city to the north and Bsaiya village to the souh. Moreover, it located within Thi-Qar and Al-Muthana Governorates. The climate of the study area is under the condition of arid climate and highly affected by desert condition. It is characterized by hot and dry summer and relatively cold winter with low rainfall Geomorphologically, several types of geomorphological units are developed the study area; units of Structural-Denudational, Denudational, Fluvial, Aeolian, Forms of Solution, Evaporation and Man-Made origin. Stratigrapgically, eight rock formations were recognized by the rock cores of the drilled boreholes, these are (from older to younger); Rus, Dammam, Jaddala, Euphrates, Ghar, Nfayil, Zahra and Dibdibba formations. Geochemistry, the change between the averages of terrestrial detritus elements SiO2, Al2O3, Fe2O3, TiO2, Na2O, K2O, Cl, and P2O5, and carbonate element (CaO and LOI) indicate change in depositional environment from marine in Dammam and Jaddala formations to continental in Dibdibba Formation. However, Zahra Formation does not reflect marine environment, but caused by dominate continental carbonate rocks. Geophisically, two gravity profiles; K and S of lengths 9.0 and 6.7 Km are situated on the boundary between two tectonic zones in the study area. A 2D forward model has been constructed along profile K, which explain a basement fault and contact within the study area. One profile for radiometric survey Ns, generally shows low radiation level for both Quaternary sediments and pre Quaternary rocks. Hydrogeologically, the Dibdibba, Nfayil and Dammam formations represent the main aquifers within the study area. The general direction of groundwater flow within the study area is toward north. Quality of the groundwater is variable, where the chloridic type represents the majority type in study area, while the sulphatic type is concentration in restricted area at western part of study area. Economically, two hundred and sixty-three rock samples were collected from the drilled boreholes in the study area for the following purposes: 1) Chemical analyzes for a total of (233) samples, the percentages identified the following: SiO2, Fe2O3, Al2O3, TiO2, CaO, MgO, SO3, Na2O, K2O and LOI. 2) 23 samples for heavy minerals test. 3) 7 samples for XRD test.