GRAVITY AND MAGNETIC SURVEYS TO DELINEATE SUBSURFACE STRUCTURES IN HOR AL-HUWAZAH AREA, SOUTH IRAQ

Abstract

Gravity and magnetic surveys were carried out to study an area located between, Amara and Qurna Cities, The results of the present survey are merged with those of the previous surveys carried out exIPC; using Oasis Montaj software to produce a unified database, which considered a new addition to update the gravity and magnetic field maps of Iraq.The most impressive result of the present gravity survey is the negative anomaly (A), found in the middle part of the studied area with NE – SW trend. This anomaly is a completion of the more extended important negative anomaly present in the vicinity of Qalat Saleh – Uzair – Qurna. It is surrounded by high gravity gradient that may be related to fault and/ or contact and may reflect the occurrence of a restricted basin, or it may reflect the negative background of Zagaros root effect. It is worth to mention that most oil fields occur along the high gradient flanks of this anomaly. The expressive positive gravity anomaly (G1 and G2), are located in the upper middle part of the area with a trend of NW – SE extending beyond the studied area. It may be attributed to uplift in the sedimentary cover corresponding to uplifts in the basement, as indicated in the basement relief map of exIPC. This anomaly may be attributed to the presence of coral reef or anhydrite elongated body present within the sedimentary column.The magnetic map of the studied area reflects mainly the effect of the basement, but several local anomalies are also detected, some of which are related to local buried iron artifacts, which act as sources of noise. Therefore, some filters were applied to enhance the magnetic picture.