Analyzing the Gravity Field of the Southern Desert of Iraq with its Possible Geological Implications Using Multi-Bidimensional Empirical Mode Decomposition Technique

Abstract

The Southern Desert of Iraq covers a vast region in southwest Iraq. The stratigraphic column comprises relatively thick sedimentary strata, which overlay a Neoproterozoic basement and dip gently towards the northeast. The ground surface is depicted by intensive karst forms of variable dimensions, especially within carbonate rocks of the Dammam Formation (Middle-Upper Eocene). In the present study, we use the Bidimensional Empirical Mode Decomposition technique for analyzing the gravity field into multi-residual fields and one regional. Analyzing and interpreting the resultant fields utilizing the geological data are the aims of this study. A free download MATLAB code is applied to the gravity data of the Southern Desert which is designed to separate the two-dimensional gridded gravity map into three residual maps and a regional one. These maps may reflect depths at different levels; shallow, intermediate, deep, and near the Moho discontinuity, respectively. According to the available information about the geology of the area, the residual maps can be interpreted in terms of shallow-depth geological structures, which have an economic interest in hydrocarbon exploration, intra-basement structures, and variation in the density of the basement terranes. The regional map, however, is interpreted to be related to a deep-seated gravity source most likely near the Moho. Further, the results illustrate an obvious relation between some of the gravity positives, in the first residual map, and the drilled exploration wells. This suggests a delineation of newly prospected structural highs. In addition, the second residual map shows gravity negatives that probably delineate basement basins/sub-basins.

Remanent Magnetization in the Proterozoic Basement Rocks of Iraq: the Southern Desert in Focus

“…Occurring remanence results in inaccurate basement depths when applying inversion methods, except when using inversion methods, which are independent of the direction of magnetization, such as the SPI and iSPI methods that depend on calculations of the rst or second local wavenumbers (Thurston and Smith, 1997;Smith et al, 1998). Al-Bahadily (2022) shows that the depth to basement map obtained from the SPI method is the most accurate among the ve magnetic inversion methods used in the Southern Desert of Iraq. In addition, con rming the presence of remanence in the basement is signi cant not only for determining the depths of sedimentary basins but also for basement lithological interpretation and for studying the tectonic and structural evolution of the area.…”

“…The TMI data of the Iraq Southern Desert (its position is shown as a black polygon in Figures 1-3) are separately run in GAMS Software since the magnetic data of the Desert were interpreted by Al-Bahadily (2022), and this would be useful when comparing with the present results. The results of implementing GAMS on the TMI-residual grid of the Southern Desert are shown in Fig.…”