Yumbarra - A Case Study in Geophysical 3D Magnetic Modelling

Abstract

Yumbarra Conservation Park, in the State's west, is one of South Australia's most unspoilt parks and, is considered to have high conservation value. In November 1999 the South Australian government re-proclaimed Yumbarra Conservation Park to allow mineral exploration and mining. Yumbarra has become a test case of how exploration can be conducted within a conservation park. After considering environmental sensitivities, the acquisition of passive remotely sensed data became the preferred methodology in order to minimise disturbance. High resolution airborne geophysics was acquired over the region to better define the Yumbarra anomaly. This data was extensively interrogated to provide solutions and models. The intent of undertaking this work was to reduce risk for the explorer and minimise any impacts of exploration on the region through the development of a more focused program based on the magnetic modelling results. Extensive depth modelling was completed where Euler depth solutions, and mrG-strings were used to augment existing data and assist in exploration program design. Utilising 3D block modelling applications PIRSA geophysicists were able to achieve an improved understanding of the target anomaly to be tested. The results provided better defined regions for drill testing, that will further minimise any surface impacts.