Helicopter EM (ZTEM–VTEM) survey results over the Nuqrah copper–lead–zinc–gold SEDEX massive sulphide deposit in the Western Arabian Shield, Kingdom of Saudi Arabia

Abstract

Magnetic and electromagnetic (EM) results from two helicopter EM surveys, a time-domain (VTEM) and AFMAG (ZTEM), are compared over the Nuqrah sedimentary exhalative (SEDEX) massive sulphide deposits in the Western Arabian Shield of the Kingdom of Saudi Arabia. The magnetic and EM data from both surveys map the major controlling structures that host the Nuqrah North and South deposits. Neither Nuqrah deposits stand out as distinctive aeromagnetic anomalies, but both EM surveys define the massive sulphide mineralised vent and bedded portions of the SEDEX orebodies. ZTEM is interpreted to be more capable in defining the larger, lower conductance and less mineralised distal portions of the SEDEX system. The modelled ZTEM also defines a down-dip extension of the Nuqrah South zone below a depth of 750 m.

Magnetic and electromagnetic (EM) results from both time-domain (VTEM and AFMAG (ZTEM) helicopter EM surveys are compared over the Nuqrah sedimentary exhalative (SEDEX) massive sulphide deposit in Saudi Arabia. The magnetic and EM data map major controlling structures but only the EM surveys are able to define the Nuqrah deposits.

Key words::

• AFMAG
• airborne
• electromagnetic
• magnetic
• SEDEX
• VTEM
• ZTEM

Acknowledgements

The authors wish to thank Ma’aden and Geotech for allowing us to present these results. We also thank both Kuncho V. Kunchev and Joel C. Black for their useful exchanges and for providing the geologic background information. We also gratefully thank the outside reviewers for their significant help in improving our paper.