New Basement Structural Division Map from Analyzing Magnetic Data of Iraq Southern Desert Using Phase Preserving Dynamic Range Compression Technique

Abstract

The Iraq Southern Desert (SD) lies in southwest Iraq and tectonically occupies a position on the stable part of the Arabian Platform. The area is characterized by a considerable thickness of Phanerozoic sedimentary sequences, generally non-magnetic, that overlie a Precambrian and reworked Proterozoic basement. The magnetic field, therefore, generally represents the responses of basement rocks. Several qualitative approaches are used for data enhancement of the potential field (gravity and magnetic) allowing for better qualitative interpretation. The present work aims to analyze the magnetic and gravity datasets of the SD and interpret them in terms of structures in the postulated basement and the sedimentary cover. In the present study, the Phase Preserving Dynamic Range Compression technique, which produces a set of dynamic range compressed images at different scales, is utilized to analyze gravity and magnetic datasets of the (SD). A free-download MATLAB code designed for this purpose is used to perform the required analyses. Large scale (long wavelengths) magnetic image, usually reflects deep sources, offers a possibility of structural interpretation of the Proterozoic basement into three blocks and sub-blocks; northwestern block, central block, and southeastern block. The blocks are separated by basement structural lows or grabens that are inferred from depth to basement maps. A small-scale wavelength image usually reflects magnetic sources at shallow basement depth, and displays different magnetic features mostly make up NE-SW lineaments. Analysis of gravity data at large- and small scales show gravity lows and lineament structures within the basement and the sedimentary cover, respectively.

Depth-to-Basement Estimates Using Magnetic Data of the Iraqi Southern Desert: A Statistical Approach

“…The SPI depth estimates are generally acceptable in the stable part of the platform i.e. the study area [29]. In addition, regions that give large differences in depth estimates are usually deep or have low magnetic susceptibility.…”

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 first 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 five magnetic inversion methods used in the Southern Desert of Iraq. In addition, confirming the presence of remanence in the basement is significant 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.…”

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.…”

“…This map is obtained by subtracting a 3rd-order polynomial surface, assumed as a regional eld, from the DRTP eld. This separation method is recommended byAl-Bahadily et al (2023) as a suitable separation technique for magnetic data in the Southern Desert of Iraq. The TMI map of Iraq, shown in Fig.…”