Caves and Mining in Brazil: The Dilemma of Cave Preservation Within a Mining Context

Abstract

The exploitation of mineral reserves in Brazil, especially limestone and iron ore, is currently restricted due to the existence of caves. The vast majority of caves documented in the country over the last 4 years (approximately 3,000) have been identified through environmental studies conducted for mining operations. To determine whether a cave should be protected or not, a series of criteria were formally established by recent (2008/2009) federal laws. Four classes of cave relevance were formally designated, based primarily on geological and biospeleological criteria. Maximum Relevance caves must be protected, together with a 250 m buffer zone. High Relevance caves may be removed, provided that two other high relevance caves, preferably within the same geological unit and containing similar characteristics, are permanently protected. However, the acquisition of areas containing caves, especially within iron ore regions, has become extremely difficult due to the high price of iron ore. Medium Relevance caves may be subject to removal, but speleological compensation must be applied. Low Relevance caves may be mined with no need for environmental compensation. Although these laws occasionally permit cave destruction, their ambiguous specifications and numerous criteria produce a highly restrictive scenario in which approximately 85 % of all caves are categorized as Maximum or High Relevance. The situation is further exacerbated by the very low minimum length of 5 m for any void to be classified a cave, producing a high number of caves regardless of lithology. Conducting a full cave environmental study, besides being financially costly, takes approximately 1.5 years to complete, primarily due to the requirement to perform two biospeleological sampling events during dry and wet seasons. The protection of several caves within mining areas has significantly decreased access to exploitable reserves, causing caves to remain under severe economic pressure. While Brazilian law emphasizes cave preservation, it provides no specific provisions for the protection of other karst features or karst aquifers.

Keywords

These keywords were added by machine and not by the authors. This process is experimental and the keywords may be updated as the learning algorithm improves.