Using Ground Magnetic Data for Edge Basic Dykes Detection, Their Structures and Tectonics, in North Ras Millan Area, Southern Sinai, Egypt

Abstract

Abstract The main aim of this search is delineated the basaltic dykes edges, as a part of the structural-tectonic inferences of North Ras Millan (NRM) area, Southern Sinai, Egypt. A ground magnetic survey was conducted, to help edge delineation of the subsurface magnetized bodies. The magnetic data analysis is based on the filters of horizontal and vertical gradients, in which the edge detection is dependent on the tilt derivative (of the horizontal and vertical derivatives) and the tilt angle of the available ground magnetic data of the concerned area. This study applied a new edge-detection filter, called the enhanced total horizontal derivative of the tilt angle (ETHDR). ETHDR is the total horizontal derivative of the ratio of the first vertical derivative to the total horizontal derivative of the first order analytical signal amplitude. This paper compares the results of the analytical signal (AS), first vertical derivative (FVD), total horizontal derivative (THDR), tilt angle (TA), horizontal tilt angle and Enhanced total horizontal derivative of the tilt angle (ETHDR). The compared applied derivatives-based filters and the enhanced total horizontal derivative of the tilt angle produce more detailed results for the shallower and deeper magnetized structures, and gives sharp edges of the basic magnetized dykes, that surrounded by basement rocks of acidic nature. Structurally, the considered area is implicated by two sets of normal faults, older Pre-Miocene normal faults of NW-SE trend (Red Sea system) and younger Miocene oblique faults of NE-SW trend (Gulf of Aqaba system) as shown from Fig. (14), the younger NE-SW faults crossed the older NW-SE faults and displaced their step-like fault blocks in right and left lateral movements of strike sense. Also, the inferred basic dykes are generated generally through their intersections and particularly through the NE-SW younger set. Tectonically, these fault systems were created, due to the NNW-SSE Alpine stress of the early Mesozoic time, in the form of NW-SE (Gulf of Suez) and NE-SW (Gulf of Aqaba) fault systems of first order oblique faults of normal slip component during the pre-Miocene, followed by the shear slip component of the Miocene and Post-Miocene times, as expressed by the tectonic model of north Eastern Egypt during the Pre-Miocene, Miocene and Post-Miocene, Abu El-Ata and Helal, (1992)