Mapping Main Structures and Related Mineralization of the Arabian Shield (Saudi Arabia) Using Sharp Edge Detector of Transformed Gravity Data

Ahmed M Eldosouky,Luan Thanh Pham,Haytham Sehsah,Mansour S Alhumimidi,Reda A Y El-Qassas,Ahmed El Bahrawy,Kamal Abdelrahman,Kevin Mickus

doi:10.3390/min12010071

Abstract

Saudi Arabia covers most of the Arabian Peninsula and is characterized by tectonic regimes ranging from Precambrian to Recent. Using gravity data to produce the lateral boundaries of subsurface density bodies, and edge detection of potential field data, a new subsurface structural map was created to decipher the structural framework controls on the distribution of gold deposits in Saudi Arabia. Moreover, we detected the relationships between major structures and mineral accumulations, thereby simultaneously solving the problem of edge detectors over complex tectonic patterns for both deeper and shallower origins. Analytic signal (ASg), theta map (TM), TDX, and softsign function (SF) filters were applied to gravity data of Saudi Arabia. The results unveil low connectivity along the Najd fault system (NFS) with depth, except perhaps for the central zones along each segment. The central zones are the location of significant gold mineralization, i.e., Fawarah, Gariat Avala, Hamdah, and Ghadarah. Moreover, major fault zones parallel to the Red Sea extend northward from the south, and their connectivity increases with depth and controls numerous gold mines, i.e., Jadmah, Wadi Bidah, Mamilah, and Wadi Leif. These fault zones intersect the NFS in the Midyan Terrane at the northern part of the AS, and their conjugation is suggested to be favorable for gold mineralization. The SF maps revealed the boundary between the Arabian Shield and Arabian Shelf, which comprises major shear zones, implying that most known mineralization sites are linked to post-accretionary structures and are not limited to the Najd fault system (NFS).

Highlights

The Arabian Shield (AS) is of economic interest as it has promising potential for metallic mineral exploitation
The regional anomaly gradient contrasts with the thickening of the crust to the east [73], suggesting that this regional gravity anomaly gradient is due to lithological crust variations
Producing a new structural map for Saudi Arabia with structurally related mineralizations was the main target of our study

Summary

Introduction

The AS is of economic interest as it has promising potential for metallic mineral exploitation. Several methods have been developed for solving these problems, including the tilt derivative method, which is an arctan function of the ratio between the vertical and horizontal gradients [21]; the theta map (TM) method, which normalizes the horizontal gradient by the total gradient [22]; the horizontal tilt angle filter, which normalizes the absolute value of the vertical gradient by the horizontal gradient [23] The latter methods can detect the edges of shallow and deep sources simultaneously, they can produce false or secondary edges not related to actual density sources [24,25]. [29] introduced the soft sign function (SF) filter, which is based on the second-order derivatives of the potential field data This method effectively improves the resolution of boundary detection results while avoiding the secondary boundary issue

Results

Discussion

Conclusion