No abstract

Petrographic study of the Sinjar and Khurmala Formations at the Zagros and Taurus Folded Zones, in northern Iraq led to the recognition of 11 carbonate microfacies that can be grouped into seven facies associations. These facies associations deposited within outer shelf, fore-reef, reef, back-reef, lagoon, shoals/bars and channels, and tempestite subenvironments of a composite isolated carbonate platform. The digenetic imprints on the recognized microfacies are prominent and dominated by micritization, dissolution, cementation, neomorphism, dolomitization, compaction, stylolitization, and precipitation of some authigenic minerals such as pyrite, glauconite, and gypsum. Isopach and depositional facies maps of the Sinjar-Khurmala successions show three depocenters in two subbasins in the study area, two of them are elongated and coincide with the Zagroside and the Taurides trends, whereas the third accords with the trend of the Sinjar graben. The reconstruction of the history of the Sinjar and Khurmala carbonates revealed four stages of basin development within two subbasins. The first stage represents the initial deposition of the Sinjar and Khurmala Formations that was preceded by the deposition of the deep marine part of the underlying Kolosh Formation. This depositional phase is characterized by submarine fans and basinal sediments. Both subbasins were partially separated by a ridge or a series of paleohighs, which had been inherited from relieves of the Cretaceous paleosurface. During the second depositional stage, the Sinjar basin is developed by growth of another reef build-up to the southeast with a general direction from southwest near Kirkuk area to the northeast near Sulamani area. During the third depositional stage, the basin was developed through the growth of isolated carbonate platform extending from the Kirkuk to the Duhok. Such platform was drowned during the transgression that covered the northern part of the Kolosh basin and southwestern part of the Aaliji basin. The final depositional stage was represented by a still stand period, when the sea level was stilled, and led to the upgrading growth during the early Highstand system tract of the carbonate shelf . As a result, during this stage, the reef facies were prograded seaward and replaced by the back-reef facies to indicate the end of Highstand during the late regression stage.

The Lower Cretaceous Zubair Formation is the most important reservoir in the south of Iraq and adjacent countries, as well as the shale intervals, may be the possible source rock. The parameters of the possible source rock within Zubair Formation are accepted, regarding quantity, quality, and thermal maturity. From the total organic carbon values standpoint, shale intervals of Zubair Formation are generally good source rocks, except in the lower parts. While the kerogen types are generally type III gas-oil prone, mix type II/III, and type II oil-prone. The main type of organic matters was amorphous organic matters, which is principally related to oil-prone source rock. The Rock-Eval Pyrolysis shows that the organic geochemical properties presented an effective and/or potential source rock depending on the values of S1, S2, and S3 and their derivatives. The source rock has started the oil expulsion, where the S1/TOC values were mainly more than 0.2 mg HC / g TOC. The modelling explains that the Zubair Formation, wholly, has been entered the onset, partially, the peak, and rarely the end of oil generation in the studied Subzones. This conclusion depends on the calculated temperatures, geothermal gradients, and Vitrinite reflectance calibration.

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Heavy metals contamination of water and soil represents a major environmental threat that is to be monitored on a regular schedule in order to avoid its negative consequences. This study is dedicated to evaluating the water and the soil state in the perimeter of Baghdad Medical City`s complex that is located adjacent to the great Tigris River. Water and soil samples were collected from three stations on both sides and middle of the river; upstream, downstream and at the complex`s wastewater discharge point to the river. Chemical and atomic absorption spectrophotometer tests have shown that the concentrations of Cd, Pb, and Ni in water and soil are within the permissible WHO limits for all upstream samples, but they increase significantly beyond the complex`s wastewater discharge location. Also, Chemical indicators have shown a similar trend for all tested samples in a clear announcement for the possible direct threat to the surrounding environment and residents/benefits, with its main spot at the medical complex, in order to initiate sudden remediation acts.