Geology

Abstract: The present work studies the environmental isotopes assess groundwater characteristics of
the different parts of the main aquifer in the northeast Missan Province in south of Iraq. Water
samples of groundwater and surface water were collected for two dry and wet seasons during the
water year of 2011-2012. The study shows that most of the groundwater in the aquifer falls above the
global meteoric water line, and all the samples fall below the Mediterranean meteoric water line,
indicating that these samples are a mixture of two water types. The tritium content of these samples
supports this conclusion. The overall conclusion of this study indicates that there are two sources of
groundwater recharge in the studied area: the ephemeral streams (Teeb and Dewerge) and major
precipitation sources. According to the tritium levels at or below one tritium unit (TU) obtained from
the water, supply wells are highly confined or “not vulnerable”. Overall, the 3H results imply that
recent recharge has taken place during the last four to five decades. In the recharge area, the high
tritium content in the southern part of the Teeb area suggests that the recharge originates from rapid
infiltration of surface runoff. Therefore, the groundwater resources in the study area should be
protected from contamination, because it will influence the aquifer in a relatively short period of time
if any contamination enters the recharge areas of the aquifer.

The present study focused on assessing the groundwater quality of the shallow aquifer in the northeastern Wasit Governorate, Iraq. The physicochemical parameters, including major cation and anion compositions, pH, total dissolved solids and electrical conductivity,
were used to assess the suitability of groundwater quality for drinking purpose by comparing with the WHO and Iraqi standards. Total dissolved solid (TDS), sodium adsorption ratio, residual sodium bicarbonate, permeability index and magnesium ratio were used for irrigation suitability assessment. For this purpose, 98 samples were
collected from the scattered shallow wells in the study area. Results indicated that the spatial distribution of TDS, EC values and major ions in these groundwater samples considerably differ from one site to another mainly due to the lithological variations of the area. The results are correlated with standards classifications to deduce the hydrogeochemical phenomena. The dominant factors in controlling
the groundwater hydrogeochemistry are evaporation and weathering in the study area. The geochemical modeling approach was used to calculate the saturation state of some selected minerals, i.e., explaining the dissolution and precipitation reactions occurring in the groundwater. The studied groundwater samples were found to be oversaturated with carbonate minerals and undersaturated with evaporates minerals. Comparison of groundwater quality in relation to drinking water standards showed that most of the groundwater samples were unsuitable for drinking purposes. On the other hand, most groundwater is unsuitable for irrigation purposes based on sodium and salinity hazards. However, soil type as well as proper selection of plants should be taken into consideration.

This work aims to evaluate the predictive capability of three bivariate statistical models, namely information value, frequency ratio, and evidential belief functions, in gully erosion susceptibility mapping in northeastern Maysan Governorate (Ali Al-Gharbi District) in southern Iraq. The gully inventory map, consisting of 21 gullies of different sizes, was prepared based on the interpretation of remotely sensed data supported by field survey. The gully inventory data (polygon format) were randomly partitioned into two sets: 14 gullies for build and training the bivariate model, and the remaining 7 gullies for validating purposes. Twelve gully influential factors were selected based on data availability and the literature review. The selected factors were related to lithology, geomorphology, soil, land cover, and topography (primary and secondary) settings. Analysis of factor importance using information gain ratio proved that out of 12 gully influential factors, eight were of more importance in developing gullies (the average merit was greater than zero). The most important factors and the training gully inventory map were used to generate three gully erosion susceptibility maps based on the three bivariate models used. For validation, the area under the operating characteristics curves for both success and prediction rates was used. The results indicated that the highest prediction rate of 82.9% was achieved using the information value technique. All the bivariate models had prediction rates greater than 80%, and thus they were regarded as very good estimators. The final conclusion was that the bivariate models offer advanced techniques for mapping gully erosion susceptibility.

A novel method has been proposed in this study for delineation of flood-prone areas through integration of catastrophe theory and analytical hierarchy process (AHP) in a geographical information system. Seven causative flood factors were selected for this purpose based on data availability and literature reviews, namely, ground surface elevation, slope angle, curvature, topographic wetness index, stream power index, curve numbers, and distance from intermittent streams. The raster maps of the factors were prepared with a cell size of 30 9 30 m. The catastrophe models were used to derive weights of the factors using weighted linear combination technique, while AHP was used to compute normalized ranks of the classes of each factor. The model was applied to demarcate the floodprone zones in northeastern parts of Southern Iraq, where flash flood is a recurrent natural hazard that causes damage to property almost every year. The study revealed that about 852 km 2 (41 %) of the study area is less susceptible, 434 km 2 (21 %) is moderate susceptible and 812 km 2 (38 %) is high susceptible to flood. The high flood-susceptible zones are mainly distributed around the intermittent streams and the low lands in the southeast, while the low flood-susceptible zones are found in the east and northeast hilly regions of the study area. The obtained result matches well with general conception of flood-prone zones in the region, which indicates that integration of catastrophe theory and AHP can provide a low cost and easily implementable method for reliable mapping of flush flood-susceptible zones.

Four seismic refraction profiles for both compressional (P) and shear (S) waves had been surveyed within AlKifil District/Babylon Governorate, Middle of Iraq, by the use of three impacts; normal, center and reverse shootings. In addition, cross-hole, down-hole and up-hole seismic refraction using couple boreholes were also conducted in the investigated site. These two techniques were done in order to delineate depths and thicknesses of the layers (soils), their dynamic elastic modulus and groundwater level underlying such establishment building may use for future landfill purposes.

Four seismic refraction profiles for both compressional (P) and shear (S) waves had been surveyed within AlKifil District/Babylon Governorate, Middle of Iraq, by the use of three impacts; normal, center and reverse shootings. In addition, cross-hole, down-hole and up-hole seismic refraction using couple boreholes were also conducted in the investigated site. These two techniques were done in order to delineate depths and thicknesses of the layers (soils), their dynamic elastic modulus and groundwater level underlying such establishment building may use for future landfill purposes. The calculations demonstrate that there are two shallow subsurface layers were found. The average of velocities and thicknesses of the first layer (consists of grayish silty sandy clay soil) are equal to 259.33, 147.83 m/sec and 6.58 m, and for the second one (consists of brownish and greenish silty clay soil with sand) are 517, 273.25 m/sec for each P and S-waves respectively. On the other hand, mean water table seems between 1.40 and 1.20 meters during Sep. 2012 and Sep. 2015 respectively. Moreover, the mean dynamic elastic constants were ranged between {κ= (69.51-605.16) Mpa, μ= (24.64-212.37) Mpa, E= (60.40-510.93) Mpa, λ= (41.85-392.22) Mpa, and, σ= (0.18-0.37)}. Site engineering information including physical and geotechnical properties were also measured and analyzed to enhance the main targets of this study. Standard penetration test and bearing capacity values were performed and calculated for the studied soils. The average of the N-values in situ is equal to (11) impacts having bearing capacity (6.10) ton/m2 at (1.5) m depth interval. It noticed that the N-value is low near the ground surface because of the saturated clay existence (medium consistency). At depth intervals between (13-15)m, the N-value was reached (43) impacts and more; this indicates that the soil is cohesion and contains high percent of sand and low clays; therefore, all depth intervals or layers in the drilling wells are considered hard media and they have bearing capacity equals to (16) ton/m2. This means that the layers corresponding to these intervals were characterized by its hardness.

GPR profiles conceptualize remains of archaeological site in Basrah have been created using finite difference time domain modeling. Dimension and architecture of the remains were taken from satellite aerial image of Google Earth application. The Modeling follows a gradual approach to simulate the remains as it were buried with focus to show the effect of surface roughness introduced to the constituent objects of the model. Results of the modeling vary from simple reflection from the buried structure to complex interaction of electromagnetic wave with subsurface conditions. Implication of roughness introduced can be seen in magnifying the attenuation, and subsequently reducing the depth of penetration.

The location and geometry of seismogenic faults are fundamental to understanding the regional seismic hazard; however, surface evidence for active faults in the seismically active central United States is rare, thus contributing to the uncertainty in the hazard estimation. Multicomponent S-wave reflection energy was acquired near the northern boundary of the New Madrid Seismic Zone across a well-constrained N61°E-oriented fault that extends above the top of Paleozoic bedrock and into near-surface Quaternary sediment in order to evaluate the effectiveness of shear-wave splitting measurements for determining azimuthal orientation of faultdeformed unlithified sediment that lack a surface manifestation. The data were analyzed within the shear-wave window (i.e., without wide-angle distortion) using orthogonal source-receiver orientations. Normalized reflection energy spectra of the main and cross-diagonal elements were rotated in 5°increments to determine fast (S1) and slow (S2) S-wave directions associated with the azimuthally anisotropic inclusion. The resultant natural coordinate system was N60°E and N30°W for S1 and S2, respectively. The S1 orientation correlated with the established N61°E fault strike. In addition, there was an average dynamic mistie of 11.3 ms that suggests 3.6% azimuthal anisotropy between the top of bedrock and ground surface. These results suggest that shear-wave birefringence can be a useful tool for defining azimuthal orientation of neotectonic inclusions that lack surface or geomorphic expression, as well as for areas that may have limited accessibility (i.e., urban environments) for deploying multiple widespread geophysical surveys.

A contaminant plume migrates within a shallow late-Tertiary gravel aquifer in an anomalous curvilinear pattern aligned with the general orientation of an underlying early-Paleozoic fault system. The bedrock faults are masked by~100-m of overlying Late Cretaceous through Quaternary sediment. Fault reactivation has been as late as Pleistocene with near-surface deformation affecting the aquifer. Near-surface geophysical attributes indicate a potential structural influence for the anomalous plume migration pattern. Specifically, the fault zones exhibit lower shear-wave velocity (100 m/s) and electrical resistivity (80 Ω-m) relative to surrounding sediment. In addition, shear-wave splitting across a well-constrained fault strand indicates the sediment has an average 3.6% azimuthal anisotropy coincident with fault strike. Variation in elastic and electrical properties, as well as spatial coincidence of the plume and geologic structure, suggest neither mechanical (i.e., consolidation) nor chemical (i.e., cementation) "healing" of the sediments have completely occurred since deformation cessation. The variation in geophysical characteristics are also indicative of a non-uniform hydraulic conductivity, thus providing a structurally controlled preferential pathway for fluid migration. These results demonstrate that integrated non-invasive geophysical methods are effective for evaluating complex geologic conditions in environmentally sensitive areas.

Nahr Umr oil field is located in the southernmost of Mesopotamian foreland basin, southeast Iraq. Even though it is one of the largest and most important oil fields in south Iraq, the time sequence of its tectonic development is still equivocal. Therefore, preacquired two-dimensional seismic reflection profiles of total length 47.65 km, time and depth structure maps, well logs information, and calculated porosity distribution surfaces of Zubair and Mishrif formations were gathered to build a simplified tectonic development model. The suggested tectonic sequence model indicated that Nahr Umr oil field was formed during Late Cretaceous-Miocene synchronous to the dominant compressional stresses due to convergent plate boundaries, Arabian and Eurasian. These stresses of northeast-southwest direction formed the field anticline fold and affected the post-Cretaceous stratigraphic sequences. The stratigraphic sequence flexure is associated with fractures and faults, particularly in the axial zone. The fractured zones produced high porosity areas which played as pathways to move the Infra-Cambrian salts, upward. The salts stopped underneath Dammam formation of the Eocene-Miocene age because of either salt depletion or overburden weight. The Middle and Late Miocene-Recent time may show subtle anticline combined with few faults, but no free surface expressions.

The Buzurgan oil field is one of the most important oil fields border in southern Iraq. Adjacent to the Fauqi and Abu Ghirab oil fields common with Iran. The 3D seismic data showed the structural and stratigraphic of the Buzurgan oil field, where the results showed that the structure is an anticline fold with two structural domes separated by a saddle, the northern culmination is shallower and less deformation. Thirty-one faults were detected and most of them at the south part of the field which are small while the north faults are larger.

A contaminant plume migrates within a shallow late-Tertiary gravel aquifer in an anomalous curvilinear pattern aligned with the general orientation of an underlying early-Paleozoic fault system. The bedrock faults are masked by~100-m of overlying Late Cretaceous through Quaternary sediment. Fault reactivation has been as late as Pleistocene with near-surface deformation affecting the aquifer. Near-surface geophysical attributes indicate a potential structural influence for the anomalous plume migration pattern. Specifically, the fault zones exhibit lower shear-wave velocity (100 m/s) and electrical resistivity (80 Ω-m) relative to surrounding sediment. In addition, shear-wave splitting across a well-constrained fault strand indicates the sediment has an average 3.6% azimuthal anisotropy coincident with fault strike. Variation in elastic and electrical properties, as well as spatial coincidence of the plume and geologic structure, suggest neither mechanical (i.e., consolidation) nor chemical (i.e., cementation) "healing" of the sediments have completely occurred since deformation cessation. The variation in geophysical characteristics are also indicative of a non-uniform hydraulic conductivity, thus providing a structurally controlled preferential pathway for fluid migration. These results demonstrate that integrated non-invasive geophysical methods are effective for evaluating complex geologic conditions in environmentally sensitive areas.

A dissertation submitted in partial fulfillment of the requirements for the degree of Doctor of Philosophy in the College of Arts and Sciences at the University of Kentucky DISSERTATION ABSTRACT OF DISSERTATION SEAR-WAVE IMAGING AND BIREFRINGENCE IN A COMPLEX NEAR-SURFACE GEOLOGICAL ENVIRONMENT Multiple geophysical and geological data sets were compiled, reprocessed, and interpreted using state-of-the-art signal processing and modeling algorithms to characterize the complex post-Paleozoic geology that overlies the southwestern projection of the Fluorspar Area Fault Complex (FAFC) in western Kentucky. Specific data included 21.5 km of SH-wave seismic reflection, 1.5 km of P-wave seismic reflection, 2 km of electrical resistivity, vertical seismic profiles, Vp and Vs sonicsuspension logs, and 930 lithologic borehole logs. The resultant model indicates three general northeast-southwest-oriented fault zones pass through the study area as southwestern extensions of parts of the FAFC. These fault zones form two significant subparallel grabens with ancillary substructures. The geometry of the interpreted fault zones indicates that they have undergone episodic tectonic deformation since their first formation. Evidence of thickening and steeply dipping reflectors within Tertiary and Quaternary sediment in the downthrown blocks indicate syndepositional movement. Subtle thickening and lack of steeply dipping intraformational reflectors in the Cretaceous suggest a more quiescent period, with sediment deposition unconformably draping and filling the earlier Paleozoic structural surface. There is also evidence that the Tertiary and early Quaternary reactivation was associated with an extensional to compressional regional stress reversal, as manifested by the antiformal folds seen in the hanging wall reflectors and the potential small-amplitude force folds in the Quaternary alluvium, as well as a clear displacement inversion along the Metropolis-loess seismic horizon in two high-resolution reflection images. A surface shear-wave splitting experiment proved to be an efficient and effective tool for characterizing shallow subsurface azimuthally anisotropic geologic inclusions in lowimpedance water-saturated sediment environments. The measured azimuthal anisotropy across a well-constrained N60ºE-striking fault exhibited a natural coordinate system that had a fast direction coincident with the fault strike and an orthogonal slow direction. This is also one indicator that faults inactive during significant geologic intervals (i.e., Holocene) do not "heal". Integrated shear-wave velocity models and electrical resistivity tomography profiles across the fault zones exhibit lower shear-wave velocities and resistivities within the deformation zones compared with values outside the boundaries. This is additional evidence that the deformed sediment does not reconsolidate or heal, but that the sediment particle configuration remains more loosely packed, providing an increase in the overall porosity (i.e., hydraulic conductivity). This can wholly or in large part explain the anomalous contaminant plume migration path that is coincident with the deformed zones of the regional gravel groundwater aquifer.

The Buzurgan oil field is one of the most important oil fields border in southern Iraq. Adjacent to the Fauqi and Abu Ghirab oil fields common with Iran. The 3D seismic data showed the structural and stratigraphic of the Buzurgan oil field, where the results showed that the structure is an anticline fold with two structural domes separated by a saddle, the northern culmination is shallower and less deformation. Thirty-one faults were detected and most of them at the south part of the field which are small while the north faults are larger.

Seismic data of two across lines have been processed. The processing sequence implied a suggested parameters that have least effects on original wavelet attributes (e.g., the amplitude and shape). This processing procedure is a legitimate enough for studying the lithological consists of geological formations as well as hydrocarbon contents. A total of 47 wiggle traces (i.e., 19 wiggle traces from line one and 28 wiggle traces from line two) have been aligned side by side according to their CDP number. The data were limited to time window of 1000-2000 m sec. Reflector amplitudes were manually picked/estimated along the all seismic wiggle traces. The picked amplitude values were plotted as contour maps. Contour maps provided preliminary indications of lithological variation from soft to hard physical properties within the formation where seismic line crosses. A number of contour lines closures in line one were noticed. These closures may be an indication of variation in the lithological consistent and hydrocarbon trap. More contour lines closures were existed in the second line. Some of them were new and the other were extension to the closure in the first line. These closures/features can be a horizontal extension to the same facies.

Multiple geophysical and geological data sets were compiled, reprocessed, and interpreted using state-of-the-art signal processing and modeling algorithms to characterize the complex post-Paleozoic geology that overlies the southwestern projection of the Fluorspar Area Fault Complex (FAFC) in western Kentucky. Specific data included 21.5 km of SH-wave seismic reflection, 1.5 km of P-wave seismic reflection, 2 km of electrical resistivity, vertical seismic profiles, Vp and Vs sonicsuspension logs, and 930 lithologic borehole logs. The resultant model indicates three general northeast-southwest-oriented fault zones pass through the study area as southwestern extensions of parts of the FAFC. These fault zones form two significant subparallel grabens with ancillary substructures. The geometry of the interpreted fault zones indicates that they have undergone episodic tectonic deformation since their first formation. Evidence of thickening and steeply dipping reflectors within Tertiary and Quaternary sediment in the downthrown blocks indicate syndepositional movement. Subtle thickening and lack of steeply dipping intraformational reflectors in the Cretaceous suggest a more quiescent period, with sediment deposition unconformably draping and filling the earlier Paleozoic structural surface. There is also evidence that the Tertiary and early Quaternary reactivation was associated with an extensional to compressional regional stress reversal, as manifested by the antiformal folds seen in the hanging wall reflectors and the potential small-amplitude force folds in the Quaternary alluvium, as well as a clear displacement inversion along the Metropolis-loess seismic horizon in two high-resolution reflection images. A surface shear-wave splitting experiment proved to be an efficient and effective tool for characterizing shallow subsurface azimuthally anisotropic geologic inclusions in lowimpedance water-saturated sediment environments. The measured azimuthal anisotropy across a well-constrained N60ºE-striking fault exhibited a natural coordinate system that had a fast direction coincident with the fault strike and an orthogonal slow direction. This is also one indicator that faults inactive during significant geologic intervals (i.e., Holocene) do not "heal". Integrated shear-wave velocity models and electrical resistivity tomography profiles across the fault zones exhibit lower shear-wave velocities and resistivities within the deformation zones compared with values outside the boundaries. This is additional evidence that the deformed sediment does not reconsolidate or heal, but that the sediment particle configuration remains more loosely packed, providing an increase in the overall porosity (i.e., hydraulic conductivity). This can wholly or in large part explain the anomalous contaminant plume migration path that is coincident with the deformed zones of the regional gravel groundwater aquifer.