Starting in the 1990’s, the systematic acquisition and storage of digital data and associated computer-generated 2D/3D models was arguably the most significant development in mineral exploration. The pre-existing datasets termed “legacy data” may have largely been abandoned because: they were considered to have lower intrinsic quality than observations or measurements made with more modern equipment; or the challenge and expense to recover (in some cases even locate!) and translate analogue or unreadable digital data in an obsolete storage medium was deemed too much trouble.

However, what is overlooked is that many of these large geophysical surveys cost millions of euros to acquire and for a variety of reasons – land disposition, development, etc. – cannot be reproduced or would cost a tremendous amount. In a brownfield or near-mine exploration scenario, operations and exploitation have depleted the ore-bodies and infrastructure would interfere with the acquisition of new data resulting in knowledge gaps.

In recognition of the value of legacy data, the Horizon 2020-funded Smart Exploration project identified exploration sites that possessed extensive legacy datasets to be re-examined in planning for new exploration programmes and generating new targets for detailed follow-up investigations. The legacy data not only offers an opportunity to reinterpret the original data but through integration with other available geoscientific information it can guide future exploration.

Notably, reprocessing and reworking legacy data for Neves-Corvo, Portugal (base metals), Ludvika Mines, Sweden (iron-oxide) and Gerolekas, Greece (bauxite) using modern algorithms and incorporating knowledge of the mineral deposits and the surrounding geology have provided valuable information about the geometry and potential extensions of the deposits. This knowledge will be used to optimize the planned geophysical surveys to identify targets for drill testing.

– Peter K. Holmes  P.Geo., Project and Innovation Manager – Horizon 2020 RIA Smart Exploration