Historic Gold Mining in the Apuseni Mountains Recorded in Stalagmite Geochemistry

Abstract

In antiquity “Patrulaterul de Aur” (The Golden Quadrilateral), ca. 550 km² of the Apuseni Mountains was one of Eurasia’s richest gold and silver mining region. It is estimated that 60 – 64 M ounces of gold have been extracted from Romania during the past 2 ka, about 75% of which was sourced from this particular area [1]. Activities such as mining and smelting of ores and the associated biomass burning produced ample amounts of aerosols that were carried downwind and accumulated as wet or dry deposition. Meteoric water remobilized these trace elements by leaching from the soil as solute or particle/colloidal phase in aqueous solution through the bedrock and into the cave. Here we present the trace elemental compositions (22 elements, obtained by means of LA-ICP-MS) in a ca. 2 ka old stalagmite from the Frumoasă Cave (Trascău Mountains, SE Apuseni Mountains; Fig. 1) as a proxy for historical Au, Ag, and Cu mining and smelting. The most prominent sites (Roșia Montană, Zlatna, and Abrud) where ores were extracted and/or processed over the past 2 ka are < 30 km upwind of the Frumoasă Cave.