INVESTIGATING THE POTENTIAL OF THE PRECAMBRIAN STRUCTURES REACTIVATION AT MAKKAH-JEDDAH REGION IN SAUDI ARABIA

Abstract

This study is aimed to investigate the reactivation potential of the Precambrian structures (Ad Damm and Fatima faults) by younger Cenozoic structures due to the opening of the Red Sea. The signs of the Precambrian structures' reactivation (if it genuinely happened) may be manifested as an offset or cross-cutting effect in the Cenozoic lineaments by the Precambrian structures. The study area is located between latitude 20°-22° N and longitude 39°-41° E in the Makkah- Jeddah Region (MJR), which is underlain by the Arabian Shield, a Neoproterozoic group of terranes. The region is seismically active, and earthquakes in the study area pose a risk to both lives and infrastructures. The Arabian Shield has three main periods with significant structural trends. For this study, only Precambrian structures and Cenozoic structures groups are considered using indications of displacement or crosscutting of the Cenozoic structures by the Precambrian structures. Landsat enhanced thematic mapper (ETM+), Shuttle Radar Topography Mission (SRTM), and Aeromagnetic data were integrated to accomplish this objective. Landsat (ETM+) and SRTM data show a coarse texture gray color unit composed of probably intrusive igneous and metamorphic rocks. These rocks cover most of the area around the Ad Damm and the Fatima faults. Additionally, a Precambrian unit with darker color and finer texture was observed in the NW part of the Ad Damm Fault. Multiple lineaments with different trending directions (NNE-SSW, NE-SW, and NW-SE) were observed on the aeromagnetic map. Previous studies suggest that these lineaments are either Precambrian or Cenozoic. All these lineaments are cutting through the Fatima Fault with no offset. The aeromagnetic map of the area shows different low and high magnetic anomalies with no patterns that can be interpreted as apparent displacement along the Precambrian structures. Based on the integrated interpretation of the utilized data in this study, there is no enough evidence of a reactivation of the Precambrian structures by the Cenozoic structures during the opening of the Red Sea.